If I remember right the main advantage of the original hemi engine design is that the dome shaped combustion chamber and spark plug mounted in the middle of the bore allows the valves to be bigger and in a better position to optimize intake and exhaust flows. The new 5.7 "hemi" is a partial hemi in that the combustion chamber is dome shaped but the spark plugs are of to the sides of the bore. Also from what I understand most new engines are partial hemis due to the dome shaped combustion chamber.
I think the history needs to be correctly understood since the nomenclature for "hemispherical" is often taken too literal.
The term actually originated in the 1930s in the aircraft engine industry. Experimentation back then indicated that considerably higher volumetric efficiencies could be realized using it when compared to other chamber designs, ie: Ricardo, wedge, F-head, etc.
I do not know, if I ever knew, who was responsible for nomenclating the chamber shape we now often refer to as "hemispherical," but the truth is that very few actual designs (designs that made it into production, that is) were a absolute true half of a sphere, or parabola. Because the valve faces are flat portions 90 degrees to the stem's centerline, the accompanying valve seat area is dictated to be equally flat. So even if the chamber was a true dome, the valve seat openings by themselves render the term "hemispherical" technically inaccurate.
Chrysler is recognized as having early interest in the "hemispherical" combustion chamber as an offshoot of their development of an aircraft engine for the government (This engine was never put into production by Chrysler for a commissioned military aircraft as far as I know. It was used mainly as a test engine, I believe.)
Pump gas, being rather punky in the 30s, 40s, and early fifties, was a major impediment to realizing increased volumetric efficiency in automobile engine design. Chrysler found that the "hemispherical" combustion chamber produced more horsepower and torque compared to other chamber shapes using then available fuels and then relatively low (by today's standards) compression ratios. They also found that when they did raise CR the "hemi" chamber was more tolerant and less susceptible to knock.
The early automobile Hemis from Chrysler had a more domed shape, but still was not a true symmetrical (parabolic) shape. As engine experimentation continued, the second generation -- if you will -- Chrysler Hemi actually had a small flat roof section at the epicenter (ie: 426). This actually gave the shape a more trapezoidal feature, but still utilizing a basic domed shape.
The fact that the new Chrysler 5.7 Hemi has two spark plugs is, in my opinion, technically irrelevant. The flat roof section at the domed epicenter still remains and from what I can tell the current 5.7 combustion chamber shape is almost exactly like the 426. The fact that there are now two spark plugs does not make a "hemi" less a hemi because the term was never literal in the first place, nor for the purpose of shape does adding another spark plug alter the primarily domed feature. A single, center spark plug really has nothing to do with whether or not a chamber shape is "hemispherical."
I think the originators of the term never intended this term to be taken literally anyway, but used as a way to define a general shape, if you will.
I agree the "hemi" is not a true dome shape but close enough. I did do a little research and I found that the advantage of the "hemi" design is that the valves are placed on opposite sides of the combustion chamber and are larger resulting in greater efficiency.
This chamber shape is usually recognized first for its ability to produce higher air flows, especially by racing enthusiasts. However, the hemi chamber has a number of technical advantages that make it more compatible for modern high-output per cubic inch engines and has several advantages over a wedge design unrelated to flow.
It is inherently high in volumetric efficiency. The chamber roof is open, allowing for streamlined ports and less crowding around the valve edges reducing overall induction resistance. In the Chrysler-executed version, the chamber shape formed at TDC has less chamber surface area in relation to volume contributing to less heat rejection and lower carbon build-up. It is a combustion environment requiring short flame travel, and this characteristic contributes to increased combustion consistency and commensurately increased combustion efficiencies at lower flow rates. But because a hemispherical chamber has inherently higher flow, the need for multivalve treatment to make HP becomes moot. Multivalve engines must make their HP and torque at higher RPMS and low end suffers. Hence, for truck engines the hemi now becomes a notable advantage. Using only two valves per chamber actually increases low-flow characteristics and comensurately increases low-RPM torque.
These characteristics were not capitalized on years ago because the hemi was more expensive to manufacture. Wedge-chambered engines of the day better utilized cast and machine operations and were efficient enough. This lent them as a preferred design for a high volume production environment.
Fortunately, advances in metals, casting and machining technology have allowed the hemispherical chambered engine to be much more viable as a production engine. The output specifications of the new 5.7 speak for themselves.
Jason5- when was that last time you checked the epa ratings on a 1500, 4x4, 4.7, automatic Ram? It is listed as 13 city, 17 highway. The 5.9 Ram of the same year is 11 city, 15 highway. So even a conservative 10% improvement will equal the 4.7 highway (seeing as they round it off to the nearest whole number, and the city will be 1 mpg less. That is assuming it is only a 10% improvement, if it's even 15% then it will equal or exceed the 4.7 mileage and then I repeat my statement of what's the point of even building the 4.7? The 2003 numbers are 1 mpg higher for the 4.7, but then again they are also 1 mpg higher for the 5.9 so they compare even better.
As Lariat said, the big benefit of the "Hemi" design is not so much the shape of the chamber but the fact that the valves are opposed. On a wedge motor they make a line down the row of cylinders, on the Hemi they run intake on top and exhaust on bottom. So the intake can just "dump" into the cylinder without any turns, and then right back out the exhaust on the other side. The 4.7 has this exact arrangement as well, and the main thing it's lacking to make more power is simply more displacement. The 4.7 HO makes what 265 hp? and the 4.7 is a 287 ci so it's pretty close. The problem is Dodge is trying to keep the 4.7 a truck motor, give on on trying to keep over 300 ft-lbs of torque and move the powerband up, and the 4.7 would make a good high revving car motor, all while improving the HP numbers considerably. That's is what GM does to sell trucks, unfortunately the lack of low end torque only makes their HP numbers better, not their acceleration ability. Actually if the 5.7 Hemi made equal torque per liter as the 4.7 HO makes (325 ft-lbs) then it would be making 394 ft-lbs (not 375). They are just tuning the 4.7 for more torque to enable it to work in a 5000 pound Ram.
I am in the process of searching for the right truck for our fifth wheel trailer. It has a GVW of 10,500 lbs and a dry weight of 7600 lbs. Has anyone out there used their new Dodge 2500 with the Hemi to pull anything that heavy and if so how was the fuel mileage and power? I'm trying to avoid a diesel truck with the noise factor being a concern. The only engine out there with reasonable fuel mileage is apparently the Hemi.
I think that the Hemi would do an OK job dragging the load you described. So would the top gas offerings from the other manufacturers. Mileage however would be pitiful. Most likely no better than 7 if your trailer is streamlined, less if you're fighting the wind. You'll have to decide if you drive enough miles in this mode to justify the added cost of the diesel. None of the new diesels make any where near the noise of their ancestors. You know that they're diesels, but the constant knocking, clinking, and clanking is gone. Very civilized machines. One thing to consider when you're making that gas/diesel decision is that you'll get a portion of the extra cost of the diesel back when you get rid of it. Not all of the extra cost is money down the drain. Also, it will probably be easier to sell when the time comes.
Has anyone seen the 1500 Hemi yet?? I know that they are do next month, but a local Chicago dealer is advertising them now. In any case all have a wonderful holiday season.
I believe the hemi engines were on the line sometime in early November. Figuring a six week delivery cycle, they should've started to appear around the 12th to the 20th of December, if I'm correct about the build start. Someone in here has ordered one and I think they've been following the delivery process. Maybe they can comment.
From what I understand they were holding them on a holding lot so that they could send good quantities all over the country at one time. I'm not sure if the customer orders got help up for this "mass introduction" as well.
I wandered around a Dodge lot to see If I could find any Hemis. I found a Ram SLT that was unlocked so had to check out the interior. (I've never actually looked in one of the new Dodges.) I'm sorry to offend any owners of one of these but what a cheap interior! And to think I was seriously considering one of these for this dynamite new engine. I'm really disappointed.
The plastic (and lots of it) just looks really, really cheap. Even the door panels are just one big hard plastic piece. At least my GMC is half carpet on the doors. This one had leather that looked and felt more like vinyl. Seat was too too short. No thigh support. Even the fake Carbon Fiber trim looked, well, fake. As I said, I'm disappointed. I really did want to like it. Even if it rides and drives fantastic I don't think I could get past that interior. Just have to hope that GM is indeed coming out wih a SuperCrew-like Crew Cab as mentioned in another thread here. Now if I had the bucks.......Harley SuperCrew!!
Beauty is as beauty does. Personnally I don't think the interior of the new RAM is all that bad. Despite the large use of one-mold plastic pieces, I think it was tastefully designed. Does it look worse than a GM? Purely a subjective call. I most certainly don't think it looks any worse than an F150 interior. Of course, they would not repel me either.
I have a friend with a 2001 Silverado who constantly makes the point about his truck's interior being "so superior" in quality and looks. Maybe. However, I haven't been in a truck of any make or model that has as many squeaks, pops, buzzes and rattles as his does. But, as long as he's happy that's all that matters. He's the one who laid down the bread.
txyank1, you got into the wrong Ram truck.The Ram Laramie model ( all leather) is the top of the line for interiors. I had a 1999 GMC Z71,4WD, extended cab with leather and all the bells ,etc. In my opion the Ram Larimie model looks and rides better , also it has more features. Go see the dealer when he is open.
I haven't paid any attention the ST or SLT models, but I just recently got my '03 Hemi with the Laramie package. I traded a '00 Silverado 2500 with the LT package (the equivalent package to the Laramie). This Laramie package is every bit as nice and comfortable as the Silverado LT package.
The interior does not look cheap, and the seats are very comfortable. I did over 1000 miles of holiday travel, and my back never got sore, which it usually did in my Chevy. The Chevy was a great truck, and the interior was very nice, but this new Dodge is of the same caliber quality and looks.
That being said, the ST and SLT packages may be a totally different story.
it wouldn't be the Laramie, so I probably won't do that. But I'm sure I'll have the opportunity to look at others some day. BTW, I have never owned an LT or SLT GM either. And I think I've only ridden in one, a few years back, prior to the '99 change. Up until then the GM seats were a little short on thigh support too. And I'll admit that GM has had some really crappy looking print patterns for the cloth seats the last couple years. The Chevy even worse than GMC and the light colors worse than the dark. But, this thread is about the Hemi, not the interiors. And on paper at least, it looks awsome!!
That is a shame about the interior on the new Dodge's. You would think that they would have a used better materials so set them apart from Ford and Chevy.
I am a former owner of a Chevy Silverado 1500 LT Z71. I always thought that the interior looked very cheap, and it had many rattles, squeaks, etc.
My new Supercrew has been great. Albeit, it looks more 'truck like', but that is fine with me. No rattles or squeaks so far. And, it rides a helluva lot better than my Chevy ever did.
And ahhh yes... the Harley Davidson Screw, what a truck!
Sorry for going 'off topic'. Just wanted to join in.
Auto manufacturers have people dedicated to developing interior designs that are appealing, functional, and durable. Each manufacturer has their own philosophy on the design of car and truck interiors. While functionality and durablilty are subject to philosophical approaches, the "appealing" aspect is much more subjective.
Older people like myself tend to be attracted to designs that a lot of other people would classify as gaudy. GM's market share has traditionally been comprised of older buyers and GM has catered to them remarkable well (ie: Buick, Olds, Cadillac). Trucks are somewhat of a different story since there are more youthful buyers in this market.
Design philosophies vary by manufacturer. While GM has traditionally aimed at the more mature buyer and place greater emphasis on style, Chrysler always seemed to be at the other end of the spectrum and designed in more funtionality or durability.
My past GM products bore this out. They were more chrome filled and asthetically appealing by older standards. By contrast, Chrysler products always seemed more bland and straightforward, not ugly, but usually understated. My wife's '89 Plymouth Acclaim was an exception. I cannot think of another car in our family that had an interior that was as rich looking without being overdone or gaudy.
Our GM products, while having pleasing interiors by most people's standard, sometimes lacked in functionality and were probably last in durability. The Chevy G20 that just departed our driveway is a good example. After four years the interior pieces just started to fall off....literally. The wood grain appliques peeled, the glitzy handles and dash components, door penels and map pockets, the headliner, just were of inferior quality and just didn't hold up. Others that I've known have had the same or similar experiences with GM-built products. Friends that had Chrysler products just never seemed to have these problems.
And as I look at what are now much older vehicles, what I use to think were understated, bland interiors of Chrysler designed cars, don't seem as dated as the GM products of the same period. Tastes in car and truck interiors, like a lot of other things, change over time. I think there is now a trend away from the overstated.
As to the materials themselves, there is a difference between the subjectively perceived "cheap looking" as opposed to lesser quality. The new Dodge RAM's interior actually impressed me as very intelligent and honest. It seemed refreshingly undistracting, but yet pleasing to the eye. By some people's standards it may appear cheap looking, but I do not believe that the materials themselves are of inferior quality or are less durable. In fact, I'd say that they might be more durable, and that's what a lot of people I would think expect in a truck.
My new Dakota has been criticized in the same way. Chrysler appearently uses one set of interiors across the entire Dakota line. They are highly functional and very durable. And I think very attractively executed. Unfortunately, the same interior of the base model appears in the SLT, and I'm sure that with a lack of a graduated upgrade by model turns some people off who are looking to buy a more upscale vehicle.
A vehicle's interior would have to be pretty out of step with my preferences to reject an otherwise well engineered, well designed and featured vehicle completely. Nothings ever perfect.
Okay, I viewed some Silverados today to compare with the RAM. First, Chevrolet has three levels of trim (base, LS vinyl-cloth, LT leather) and are model designated. The RAM has four (base vinyl, deluxe cloth trimmed, premium cloth trimmed, and leather). In the RAM, the vinyl is only available on the base model, and the leather is only available on the SLT Plus.
The RAM's base vinyl looked cold and commercial, especially compared to the Chevrolet's vinyl and cloth combination. I think in the base model the Chevrolet's version looks a little better. This needs to be qualified, however. I was only able to compare a RAM in dark charcoal to a Silverado in tan and dark charcoal. Color does make a difference. The dark charcoal in the Chevrolet looked just as cold and commercial as the RAM's, in my opinion.
I was able to compare a Silverado LT (leather) to a RAM in leather. They were both tan in color. To my eye I thought the RAM's looked better. In actuality, both were very well executed, once again in my opinion. I was surprised at how the two seemed so similar in approach and appearance. The seats backs on the GM truck were noticeably thicker. Whether this makes them more comfortable, I don't know. I didn't sit in any of these and comfort is subjective anyway's. Thicker seats do not automatically mean more comfort. The RAM used a two-color leather trim which I though was much less boring. Just for the record, I'm not a fan of leather in automobiles.
In the middle were the two RAM cloth interiors compared to the Chevrolet LS cloth. Once again color made the difference to my eye. In tan I thought the LS interior looked about the same as the RAM's premium. Again, the GM truck had noticeably thicker seat backs. However, there is a lot of black plastic centered around the instrumentation and that came off as much "cheaper" looking to my eye. The RAM's white-faced instrumentation and two-color dash trim is much more eye pleasing and appealling to my eye.
In dark charcoal the RAM's cloth interior seats looked a little outclassed by the Silverado in the same color. The door panels on the LS utilized more cloth inserts, most noticeable at the front lower portion of the door. This breaks up the solid "plastic" appearance better than the RAM's more solid, one-piece look. The RAM offers a larger map pocket area that seemed to emphasis this, too.
After I was able to look at these two vehicles and concentrate on the interiors for a while, I realized that there is a subliminal implication that could well be a two-edged sword for either manufacturer. When posed to think about the subjective quality known as beauty, the dichotomy of implication surfaced. I began to look at these two as being so very close, which triggered the question, "which one then is more durable?" I can see that from a certain perspective, whatever is considered to be more esthetically appealing in the GM version will be an equal disadvantage to those concerned about how the interior will stand up to everyday use, wear and tear. It's easier for cloth to show and get dirtier, suffer damage. Based on touch and feel, there does not appear to be any quality difference in plastic between these two trucks. To some less cloth might be an advantage.
After close scrutiny, I came away surprised at how close the interior engineering and design approaches of these two vehicles really were. I did and still think the RAM's interior is tastefully done in cloth, even with a more one-piece look to the door panels. Depending on color, the RAM's seats might look a little outclassed to some eyes. In leather, I think the RAM is better executed, mostly because of the multi-colored dash, leather trim, and less seams on the door panels.
Of course, I can't help suspecting that a side-by-side comparison of the interior pieces -- BY THEMSELVES -- with the makers name unattached, might yield vastly different opinions from a lot of people.
Well I finally checked on all the choices out there and ordered a Ram 1500 with the Hemi. I was thinking I'd just keep it simple and a regular cab much like my current Dakota R/T is, but then I thought I'd really like to live with this truck for 7 years or more and use it as the family vacation truckster. So I went with a almost fully optioned SLT Quad Cab. I didn't get the Laramie, or leather, or side air bags, or infinity radio, but I did get everything else. I also wanted the 2wd. Better handling, better ride, better gas mileage, more power, and less stuff to break. Oh, and the $3000 saved is what paid for all the extra options! the 3-4 months out of the year the 4x4 is handy (not necessary) is just not worth the drag it is the other 8 months of the year. I live in Montana and the 2wd Dakota R/T has served as my daily driver for 2 winters now just fine. So anyway, Dakota is up for sale and the Ram will probably be April 1st at the earliest. It ended up being just a hair under $26,000 after all taxes, title, tags, and rebates. I did learn that the Hemi 1500 2wd is rated 14 city and 18 highway. This is 1 MPG worse then the same truck with a 4.7 and 1 mpg better then the 5.9. It is also the same rating a 2wd automatic avalanche gets which is probably the closest Chevy to the Quad cab ram. But who am I kidding, the reason I bought it was what Chevy seats 6 comfortably, costs $26,000 with power everything, and has 345hp? The closest competitor IMO is the Harley Ford which has leather, less HP, but more torque for over $10,000 more! $2500 more for the Laramie package would add all the luxuries of the Harley. Personally I'm just glad Dodge lets you pick how you want your Hemi wrapped, and doesn't force the top motor choice down your throat mixed with other over priced packages.
I took a test drive in a one ton HO Cummins equipped quad with man trans a few weeks back. I am considering the half ton Hemi with man trans for next truck purchase. If the trans I tested is the same as they are using in front of the Hemi, they can count me out. Absolutely the worst shifting manual transmission that I've ever had the displeasure of attempting to row. EVERY gear change was an adventure. Ridiculously notchy and the different gears seemed as if they were hiding from me. I know it would have gotten better with familiarity and age, but I wonder how much better. I have 7 speed mans in tandem axle HD trucks that shift better, even without using the clutch, than that thing did.
You can't order the manual in the 1500 and last I heard the manual was on hold for even the 2500 hemis as well. I ordered the automatic which is the 545rfe. Same transmission that has been in the Grand Cherokees for awhile but supposedly for the Hemi it has a few parts beefed up a bit. So it's a 5 speed automatic with dual 2nd gears, technically that's 6 speeds but you will never see more then 5 when shifting through them. Also the last 2 are overdrive gears and the final gear is really almost useless, it's just to reduce highway cruising noise. I ordered the 3.92 gears with limited slip, but the tires are 31 inches tall even on the 2wd, so I think 4.56 gears will be one of the first changes. We'll see, compared to my R/T the 5.7 Hemi has 30 more ft-lbs of torque and a lower 1st gear in the transmission, so maybe it will jump off the line just as well. Then again the R/T has 28 inch tall tires, and weighs 800 pounds less.
When I bought my half ton quad a little over a year ago, there was no manual trans to be had. Couldn't even order one and customer service didn't know when one would be available. It was several months before the 5-speeds started showing up. Guess the man trans behind the 4.7's won't stay together behind the Hemi. Probably 95+% will want autos so I suppose it's understandable that they aren't in a hurry to come up with one. Does Dodge build their own man trans, or do they go to an independent supplier for them? Wonder how long it will be before the Hemi shows up in a Dakota. Isn't the Hemi smaller and lighter than the 5.9L? That would be an interesting little package now, wouldn't it?
You can say that Chrysler use to build their own light and meduim duty units when they wholly owned New Process Gear. They are now in partnership with GM and New Process Gear is now called New Venture (Syracuse, NY). Typically Chrysler uses New Venture transmissions and I think most are similar to those used in GM truck platforms with perhaps small differences.
I read an article some time back about the manual for the new Hemi RAM. I can't seem to place the piece at the moment, but I think Dodge is developing a totally new manual gear box for the 5.7 engine. I'm sorry, but I can't recall if this is going to be a New Venture unit or from somebody else. I think it's coming from New Venture. I do remember that the development was delayed.
With much anticipation I test drove a new Hemi this past weekend. Two things stood out to me. First, the exhaust sounded great, much better than the 4.7 or 5.9. Second, the acceleration was not nearly as quick as I expected. I'm pretty sure that a 5.3 Chevy will accelerate faster than the Hemi. I think that's unfortunate. With peak HP at 5600 RPM and peak torque at 4400 RPM, does the Hemi make a lot of sense for a truck motor? How often will a truck driver rev their motor that high anyway? Don't get me wrong, I am a big fan of the new Ram, I just was expecting a bit more out of the Hemi.
In my opinion, yes, a hemispherical combustion chambered motor does make a lot of sense in a truck platform. Of course, its how the engineers executed the motor that makes the difference.
Keep in mind that despite the peak torque rating, the 5.7 hemi produces over 300 lbs. feet of it at idle speed. I haven't seen a HP curve of the 5.7, but with such a short torque curve I wouldn't be surprised that the HP at 1200 RPM is more than the 5.3 GM.
As to acceleration, the true test is actual time. A seat-of-the-pants comparison can be very misleading. My wife's Avalon at 40 MPH seems like its going much, much faster than my Dakota at 75.
I pretty sure that Hemi RAM 1500 production started sometime in November. Not sure of the actual date. I happen to see the product announcement literature that was sent to Dodge dealers and that indicated that order taking was to start 1 November 2002.
there should be some 1500 hemis on dealer lots now. one big dealer in nebraska has several hemi equipped trucks posted on his website.
dusty,
according to a recent news article...dc bought out GM's portion of new venture gear.
radrluv1,
your impressions of the hemi not being particulary fast match mine...but i was driving a regular cab 2500 4x4. i haven't had a chance to test a half ton hemi yet. seat of the pants feel is really hard to judge especially concerning the hemi automatic trucks. the 5-45rfe tranny is so smooth that it almost seems to blunt performance. but, it's a learn as you drive unit so the shifts would prolly "crispin" up over time. i'm gonna have to mosey out to the local lot next week and see if they have any half ton hemis.
for the interior discussion,
imo, without going into long detail, i think the ram currently has the most pleasing interior look and feel of the big three. dodge's dash is definitely better than either ford's or gm's. ford has the acres of plastic look, while gm, despite being better than ford, still reminds me too much of fisher price toys. too many buttons are the light grey colour and feel rubbery! yuck. plus, i'm not sure why, but gm trucks always display too many interior rattles/buzzes and clicks for my tastes...
The true performance of the hemi will not be known until we see 0-60 mph times. I am hoping that Motor Trend does a comparison of the hemi to both the Chevy Silverado and Ford F150.
The information I have seen indicates that 89 octane fuel is recommended and 87 octane is acceptable. With mileage in the 13/17 or 14/18 range, the extra 5-10% cost for the 89 octane would be rather significant. What would be the benefit to using 89 octane? Better performance, durability??
Emale- plus it's only a $700 option over the 4.7. So for a 1 mpg penalty and $700 you get 110 hp and 70 ft-lbs of torque, and a higher tow rating.
Something else about the seat of the pants feel of the 5.7 is that supposedly the drive by wire system pulls out some throttle, on launch and during shifts to keep it smooth, and probably reduce strain on the transmission. I don't know how this will "learn" with driver and break in period. Or if aftermarket will figure out ways to firm up shifts and apply max power possible, but I sure hope so, and soon! Keep in mind that seat of the pants feel is all about torque and gearing too. 350 ft-lbs will accelerate an identical truck equally at 2000 rpm as it does at 4000 rpm. At 4000 rpm though the motor is making twice the HP, still you only feel torque. The advantage of making the torque longer into high rpms, is that you can have that good pull for a long time, and keep the truck in the lower gears (multiplying the torque) longer as well. The real test will be in the 1/4 mile numbers but even the previous 5.9 rams always ran similar times to the 5.3 Chevys in side by side comparison articles, I'd imagine the 5.7 to be a good 1/2 to 1 sec quicker.
I don't think 0-60 is a good measure of performance, 1/4 mile is a much better indicator. If you really aren't into performance above 60 mph then the 1/8 mile is a better test. Problem is that the 0-60 is a time to speed test, and in reference to racing can be misleading. Meaning take to close cars, the car that is faster 0-60 won't necessarily be in the lead at that 60 mph point. It's hard to fathom, but it's played out every day at the track, even with identical reaction times on a side by side run the car with the higher MPH at the finish line is not always the first across. Also the 0-60 numbers are harder to measure with definite accuracy (measured at best in tenths) like timing lights at a drag strip (always measured in thousandths.)
funny you should mention the electronic throttle. when i test drove that heavy duty hemi a couple months ago, the throttle feel was odd to me. did indeed feel lazy or slow to register my foot's input. but it did make the truck feel very smooth. it sorta added to the leisurely like feeling that came across during the test drive. all together the ultrasmooth tranny...slow to react throttle and i'm sure mighty heft of the 3/4 ton frame took away some of the "urgency" i had expected to experience. a little throttle tweaking may well help this. and dropping the hemi into a 1/2 ton won't hurt either.
about the tranny, i suspect you are right about them employing some torque management into the computer software. the 5-45rfe is afterall the same tranny that is behind the 4.7l. hopefully they have indeed beefed it up for the hemi and are not just relying on torque management to get by with the hemi!
anyway, the one thing that did really impress me about the hemi was that it idled very smoothly! much more smoothly than any old 360 i've ever driven or riddin in.
and I don't notice any diiference from the 350 Throttle-body engines I used to have. Or as far as that goes from my '99 4.8, which I 'm not sure was d-b-w. When they started using the computers to control things is when the throttle response got fuzzy.
......between the 4.7 and 5.7 are no different than the incremental engine selections from Ford and GM. The real difference, I think, will be for those with a more impatient driving style and short trip/stop & go driving scenarios where its liking to realize the same type of MPG results as the older 5.9 engine.
yeah, but the hp/tq jump from the 4.7l to the 5.7l is much more "emphatic" vs the hp/tq jump between the differing gm and ford v8s...that alone will prolly help folks decide to go for the hemi which apparently is nearly as efficient overall as the 4.7l.
since you seem to know about these things...what is the tq rating of the 46re tranny that serves duty behind the 360? the reason i ask is because i found it strange that chrysler is using a lower torque rated tranny (5-45rfe) behind the hemi vs the one behind the 360. i presume the torque rating of the 5-45rfe is lower than the 46re because of the way chrysler names their trannies. the 6 in 46re means it has a higher torque capacity than the 45rfe or 5-45rfe. just found it odd that the hemi tranny wasn't called 5-46rfe or something like that...any input on this?
Well, the current nomenclature system that Dodge uses has been described to me this way:
1st digit = number of forward speeds 2nd digit = torque rating in hundred pounds, feet (minimum) 3rd alpha = (R) rear wheel drive 4th alpha = (E) electronic
Older, non-electronic shift control trannies omitted the fourth character (ie: 44R)
Unfortunately, I've been unable to find out exactly how the 545RFE fits this scheme. I could guess that the first "5" equates to actual number of distinct ranges, but in "Drive" mode only four forward speeds are realized during a normal shift pattern. I've no idea what the "F" would stand for and why the sequence changes if we assume that the "E" stands for electronic.
Some service literature that my dealership had indicated that the 545RFE used with the 4.7 is rated at an input torque of 435 lbs. ft. This should be more than adequate for a 4.7 equiped truck. It should also work with the 5.7 since the max torque rating is 345 lbs. ft., but I would think that a manufacturer would want a little more margin with an engine of that level of power. Then again, my wife's cousin, a transmission tech., indicated once that some other auto trannies don't have much of a margin at all.
I did read that the 545RFE got some changes for the 5.7, a couple I'd already mentioned. I wouldn't be surprised if there were more, although pump pressures probably wouldn't need to change a whole lot since the 5.7 RAM gets the same axle ratio and tire diameter as the 4.7 version.
I seem to recall reading that Chrysler is developing their next generation of high output truck transmissions built around the 545RFE. I've been told that there will be a new RFE-based transmission for the diesel due out soon to replace the 47RE.
Well, the current nomenclature system that Dodge uses has been described to me this way:
1st digit = number of forward speeds 2nd digit = torque rating in hundred pounds, feet (minimum) 3rd alpha = (R) rear wheel drive 4th alpha = (E) electronic
THAT'S KINDA WHAT I THOUGHT TOO, BUT IT REALLY DOESN'T WORK...CAUSE THEN THE 46RE (600LB/FT) WOULD HAVE BEEN STURDY ENOUGH FOR THE CUMMINS. INSTEAD DODGE HAS A 47RE TO HANDLE THE LO OUTPUT CUMMINS.
Unfortunately, I've been unable to find out exactly how the 545RFE fits this scheme. I could guess that the first "5" equates to actual number of distinct ranges, but in "Drive" mode only four forward speeds are realized during a normal shift pattern. I've no idea what the "F" would stand for and why the sequence changes if we assume that the "E" stands for electronic.
FROM WHAT I UNDERSTAND, THE 5-45RFE DOES INDEED USE 5 FORWARD RATIOS IN NORMAL DRIVING. THERE IS AN ALTERNATE 2ND GEAR RATIO FOR KICKDOWN (SO REALLY IN TOTAL THERE ARE SIX RATIOS AVAILABLE IN THAT TRANNY RIGHT NOW, BUT ONLY FIVE ARE USED IN A NORMAL SHIFT SEQUENCE). THE WAY I UNDERSTAND IT, DODGE BASICALLY TOOK THE 45RFE THAT WAS INTRODUCED IN LATE '98 AND WAS ABLE TO "PROGRAM" IN ANOTHER OVERDRIVE RATIO FROM THE PLANETARY GEARSET. I DON'T REALLY UNDERSTAND HOW THAT ALL WORKS BUT APPARENTLY THEY COULD ALSO GET MORE RATIOS OUT OF THAT SAME GEARSET IF THEY WANT. I WAS TOLD THIS BY A JEEP TECH.
WHY THEY DIDN'T NAME THE 5-45RFE JUST THE 55RFE I DON'T REALLY UNDERSTAND EITHER. BTW, RFE STANDS FOR REAR WHEEL DRIVE FULLY ELECTRONIC.
Some service literature that my dealership had indicated that the 545RFE used with the 4.7 is rated at an input torque of 435 lbs. ft. This should be more than adequate for a 4.7 equiped truck. It should also work with the 5.7 since the max torque rating is 345 lbs. ft., but I would think that a manufacturer would want a little more margin with an engine of that level of power. Then again, my wife's cousin, a transmission tech., indicated once that some other auto trannies don't have much of a margin at all.
ACTUALLY THE MAX TORQUE OF THE HEMI IS 375 LB/FT. BUT YOU ARE RIGHT, MANY CAR MAKERS DON'T OVERBUILD THEIR TRANNIES. I WISH THEY WOULD!
I seem to recall reading that Chrysler is developing their next generation of high output truck transmissions built around the 545RFE. I've been told that there will be a new RFE-based transmission for the diesel due out soon to replace the 47RE.
LAST I HEARD ON THIS THE HO CUMMINS WILL BECOME AVAILABLE SOON WITH A TRANNY TERMED 48RE. THAT MAKES ME THINK THE 48RE IS STILL BASED OFF THE OLD TRANNY LINE AND NOT THE NEW FULLY ELECTRONIC UNITS...FWIW.
You know, I originally thought that the 545RFE was a 5-speed transmission with two separate 2nd gear ratios. But a local transmission tech here said that it really is a 4-speed and I guess because of the "4" in the model reference, I started to assume he was right. I once tried counting the shifts on my Dakota and it seems that the 2-3 and 3-4 shifts are so imperceptible that I was never sure when or even if it shifted, even by watching the tachometer.
Yes, I did read that Dodge would introduce a "48RE" for the diesel, in fact that was sometime back. It was more recently that I read something about new(er) versions of the 545RFE. I might've been mistaken about that being developed for the diesel, and there was some talk about the 5.7 hemi being punched out to one or maybe two larger displacements. That might explain some beefier versions of the 545RFE.
As I write this the thought occurs that maybe Dodge developed the 545RFE transmission FIRST with a 5.7 hemi or stronger motor in mind, then just used it on the 4.7 when it was introduced.
A friend of mine who's a diehard GM guy recently drove my Dakota, and although he was straining to find something to criticize, did say that the Dakota's transmission was exceptionally smooth and responsive. From this guy that was saying a lot!!
As described to me, the current "R" series is very much an offspring of the earlier A704 and A727 transmissions. There's a fellow on the web that answers auto transmission problems [bjr1a [no_reply@yahoogroups.com] and he has made reference to this a couple of times. Again, a local tech here said that the basic architecture of the current "R" series is very similar to the A704 & 727, with another speed range, overdrive, and electronic shift control added. The A704 & A727s were exceptionally strong and reliable transmissions.
A 48RE should be way more than adequate for the diesel. I know there's been complaints about the 47RE in that application, but most of the troubles that I've read have been shift solenoid related. Of course, I've come to the conclusion that a majority of diesel truck owners are convinced that, just because these are diesel engines, these vehicles should be able to tow 20,000 pounds all of the time.
I believe the added 2nd gear in the 5 speed autos comes from shifting the OD solenoid between the 2nd and 3rd gears. This allows the normally 4 speed tranny to appear to have an extra gear.
I have never really understood how they keep coming up with different ratios in the identical transmission either. The 45rfe came out on the 99 Grand Cherokees, but was replaced with the 545rfe. Here's the weird part, if you have a 45rfe you can pedal it on down to the dealer and in 5 minutes you can drive out with a 545rfe, just by re programming the 45rfe. So anyway there have always been the dual second gears but what the 545rfe adds is a dual overdrive, or a second overdrive. I have a feeling they may be actually able to split any of the gears in the 545rfe with software, but I wonder if that makes a total possible ratios 8 or 6? Technically the 46re should be stronger then the 545rfe but I think that even though they did beef up the 545rfe for the Hemi applications they kept the name the same so people would think it was a proven design. Really stronger internals in the old case doesn't seem to deserve a re-naming in my book either. Maybe they could call it a "545rfe HD" or something. The 727 (which is really the same as a 46re minus the overdrive unit) was used behind the 440-6 and 426 Hemis, although I'm sure it was built with stronger internals back then then it is now.
Here is some info from the moparchat web board on Ram transmissions:
like you said i'm pretty sure the 44re..46re..47re are fairly close decendents of the old torqueflite/727...but from what i heard from the jeep tech the 45rfe/5-45rfe are heavily based on the fwd electronic automatic. as scarey as that sounds, i'm sure the rwd units are much stronger than their fwd brothers...
fyi...here is a cut and paste from daimler media on the 5-45rfe...it certainly appears from this that the 5-45rfe would indeed use five ratios in normal driving...the difference between the 4th and 5th overdrive is so slight that you might not even be able to tell when it goes into 5th...maybe by the tach but prolly not seat of the pants.
TRANSMISSION: 5-45RFE — AUTOMATIC FIVE-SPEED
Description Three planetary gear sets, one overrunning clutch, full electronic control, electronically controlled converter clutch
Comments
The term actually originated in the 1930s in the aircraft engine industry. Experimentation back then indicated that considerably higher volumetric efficiencies could be realized using it when compared to other chamber designs, ie: Ricardo, wedge, F-head, etc.
I do not know, if I ever knew, who was responsible for nomenclating the chamber shape we now often refer to as "hemispherical," but the truth is that very few actual designs (designs that made it into production, that is) were a absolute true half of a sphere, or parabola. Because the valve faces are flat portions 90 degrees to the stem's centerline, the accompanying valve seat area is dictated to be equally flat. So even if the chamber was a true dome, the valve seat openings by themselves render the term "hemispherical" technically inaccurate.
Chrysler is recognized as having early interest in the "hemispherical" combustion chamber as an offshoot of their development of an aircraft engine for the government (This engine was never put into production by Chrysler for a commissioned military aircraft as far as I know. It was used mainly as a test engine, I believe.)
Pump gas, being rather punky in the 30s, 40s, and early fifties, was a major impediment to realizing increased volumetric efficiency in automobile engine design. Chrysler found that the "hemispherical" combustion chamber produced more horsepower and torque compared to other chamber shapes using then available fuels and then relatively low (by today's standards) compression ratios. They also found that when they did raise CR the "hemi" chamber was more tolerant and less susceptible to knock.
The early automobile Hemis from Chrysler had a more domed shape, but still was not a true symmetrical (parabolic) shape. As engine experimentation continued, the second generation -- if you will -- Chrysler Hemi actually had a small flat roof section at the epicenter (ie: 426). This actually gave the shape a more trapezoidal feature, but still utilizing a basic domed shape.
The fact that the new Chrysler 5.7 Hemi has two spark plugs is, in my opinion, technically irrelevant. The flat roof section at the domed epicenter still remains and from what I can tell the current 5.7 combustion chamber shape is almost exactly like the 426. The fact that there are now two spark plugs does not make a "hemi" less a hemi because the term was never literal in the first place, nor for the purpose of shape does adding another spark plug alter the primarily domed feature. A single, center spark plug really has nothing to do with whether or not a chamber shape is "hemispherical."
I think the originators of the term never intended this term to be taken literally anyway, but used as a way to define a general shape, if you will.
Bests,
Dusty
It is inherently high in volumetric efficiency. The chamber roof is open, allowing for streamlined ports and less crowding around the valve edges reducing overall induction resistance. In the Chrysler-executed version, the chamber shape formed at TDC has less chamber surface area in relation to volume contributing to less heat rejection and lower carbon build-up. It is a combustion environment requiring short flame travel, and this characteristic contributes to increased combustion consistency and commensurately increased combustion efficiencies at lower flow rates. But because a hemispherical chamber has inherently higher flow, the need for multivalve treatment to make HP becomes moot. Multivalve engines must make their HP and torque at higher RPMS and low end suffers. Hence, for truck engines the hemi now becomes a notable advantage. Using only two valves per chamber actually increases low-flow characteristics and comensurately increases low-RPM torque.
These characteristics were not capitalized on years ago because the hemi was more expensive to manufacture. Wedge-chambered engines of the day better utilized cast and machine operations and were efficient enough. This lent them as a preferred design for a high volume production environment.
Fortunately, advances in metals, casting and machining technology have allowed the hemispherical chambered engine to be much more viable as a production engine. The output specifications of the new 5.7 speak for themselves.
Dusty
As Lariat said, the big benefit of the "Hemi" design is not so much the shape of the chamber but the fact that the valves are opposed. On a wedge motor they make a line down the row of cylinders, on the Hemi they run intake on top and exhaust on bottom. So the intake can just "dump" into the cylinder without any turns, and then right back out the exhaust on the other side. The 4.7 has this exact arrangement as well, and the main thing it's lacking to make more power is simply more displacement. The 4.7 HO makes what 265 hp? and the 4.7 is a 287 ci so it's pretty close. The problem is Dodge is trying to keep the 4.7 a truck motor, give on on trying to keep over 300 ft-lbs of torque and move the powerband up, and the 4.7 would make a good high revving car motor, all while improving the HP numbers considerably. That's is what GM does to sell trucks, unfortunately the lack of low end torque only makes their HP numbers better, not their acceleration ability. Actually if the 5.7 Hemi made equal torque per liter as the 4.7 HO makes (325 ft-lbs) then it would be making 394 ft-lbs (not 375). They are just tuning the 4.7 for more torque to enable it to work in a 5000 pound Ram.
Bests,
Dusty
Just have to hope that GM is indeed coming out wih a SuperCrew-like Crew Cab as mentioned in another thread here. Now if I had the bucks.......Harley SuperCrew!!
I have a friend with a 2001 Silverado who constantly makes the point about his truck's interior being "so superior" in quality and looks. Maybe. However, I haven't been in a truck of any make or model that has as many squeaks, pops, buzzes and rattles as his does. But, as long as he's happy that's all that matters. He's the one who laid down the bread.
Dusty
The interior does not look cheap, and the seats are very comfortable. I did over 1000 miles of holiday travel, and my back never got sore, which it usually did in my Chevy. The Chevy was a great truck, and the interior was very nice, but this new Dodge is of the same caliber quality and looks.
That being said, the ST and SLT packages may be a totally different story.
But, this thread is about the Hemi, not the interiors. And on paper at least, it looks awsome!!
I am a former owner of a Chevy Silverado 1500 LT Z71. I always thought that the interior looked very cheap, and it had many rattles, squeaks, etc.
My new Supercrew has been great. Albeit, it looks more 'truck like', but that is fine with me. No rattles or squeaks so far. And, it rides a helluva lot better than my Chevy ever did.
And ahhh yes... the Harley Davidson Screw, what a truck!
Sorry for going 'off topic'. Just wanted to join in.
Older people like myself tend to be attracted to designs that a lot of other people would classify as gaudy. GM's market share has traditionally been comprised of older buyers and GM has catered to them remarkable well (ie: Buick, Olds, Cadillac). Trucks are somewhat of a different story since there are more youthful buyers in this market.
Design philosophies vary by manufacturer. While GM has traditionally aimed at the more mature buyer and place greater emphasis on style, Chrysler always seemed to be at the other end of the spectrum and designed in more funtionality or durability.
My past GM products bore this out. They were more chrome filled and asthetically appealing by older standards. By contrast, Chrysler products always seemed more bland and straightforward, not ugly, but usually understated. My wife's '89 Plymouth Acclaim was an exception. I cannot think of another car in our family that had an interior that was as rich looking without being overdone or gaudy.
Our GM products, while having pleasing interiors by most people's standard, sometimes lacked in functionality and were probably last in durability. The Chevy G20 that just departed our driveway is a good example. After four years the interior pieces just started to fall off....literally. The wood grain appliques peeled, the glitzy handles and dash components, door penels and map pockets, the headliner, just were of inferior quality and just didn't hold up. Others that I've known have had the same or similar experiences with GM-built products. Friends that had Chrysler products just never seemed to have these problems.
And as I look at what are now much older vehicles, what I use to think were understated, bland interiors of Chrysler designed cars, don't seem as dated as the GM products of the same period. Tastes in car and truck interiors, like a lot of other things, change over time. I think there is now a trend away from the overstated.
As to the materials themselves, there is a difference between the subjectively perceived "cheap looking" as opposed to lesser quality. The new Dodge RAM's interior actually impressed me as very intelligent and honest. It seemed refreshingly undistracting, but yet pleasing to the eye. By some people's standards it may appear cheap looking, but I do not believe that the materials themselves are of inferior quality or are less durable. In fact, I'd say that they might be more durable, and that's what a lot of people I would think expect in a truck.
My new Dakota has been criticized in the same way. Chrysler appearently uses one set of interiors across the entire Dakota line. They are highly functional and very durable. And I think very attractively executed. Unfortunately, the same interior of the base model appears in the SLT, and I'm sure that with a lack of a graduated upgrade by model turns some people off who are looking to buy a more upscale vehicle.
A vehicle's interior would have to be pretty out of step with my preferences to reject an otherwise well engineered, well designed and featured vehicle completely. Nothings ever perfect.
Dusty
The RAM's base vinyl looked cold and commercial, especially compared to the Chevrolet's vinyl and cloth combination. I think in the base model the Chevrolet's version looks a little better. This needs to be qualified, however. I was only able to compare a RAM in dark charcoal to a Silverado in tan and dark charcoal. Color does make a difference. The dark charcoal in the Chevrolet looked just as cold and commercial as the RAM's, in my opinion.
I was able to compare a Silverado LT (leather) to a RAM in leather. They were both tan in color. To my eye I thought the RAM's looked better. In actuality, both were very well executed, once again in my opinion. I was surprised at how the two seemed so similar in approach and appearance. The seats backs on the GM truck were noticeably thicker. Whether this makes them more comfortable, I don't know. I didn't sit in any of these and comfort is subjective anyway's. Thicker seats do not automatically mean more comfort. The RAM used a two-color leather trim which I though was much less boring. Just for the record, I'm not a fan of leather in automobiles.
In the middle were the two RAM cloth interiors compared to the Chevrolet LS cloth. Once again color made the difference to my eye. In tan I thought the LS interior looked about the same as the RAM's premium. Again, the GM truck had noticeably thicker seat backs. However, there is a lot of black plastic centered around the instrumentation and that came off as much "cheaper" looking to my eye. The RAM's white-faced instrumentation and two-color dash trim is much more eye pleasing and appealling to my eye.
In dark charcoal the RAM's cloth interior seats looked a little outclassed by the Silverado in the same color. The door panels on the LS utilized more cloth inserts, most noticeable at the front lower portion of the door. This breaks up the solid "plastic" appearance better than the RAM's more solid, one-piece look. The RAM offers a larger map pocket area that seemed to emphasis this, too.
After I was able to look at these two vehicles and concentrate on the interiors for a while, I realized that there is a subliminal implication that could well be a two-edged sword for either manufacturer. When posed to think about the subjective quality known as beauty, the dichotomy of implication surfaced. I began to look at these two as being so very close, which triggered the question, "which one then is more durable?" I can see that from a certain perspective, whatever is considered to be more esthetically appealing in the GM version will be an equal disadvantage to those concerned about how the interior will stand up to everyday use, wear and tear. It's easier for cloth to show and get dirtier, suffer damage. Based on touch and feel, there does not appear to be any quality difference in plastic between these two trucks. To some less cloth might be an advantage.
After close scrutiny, I came away surprised at how close the interior engineering and design approaches of these two vehicles really were. I did and still think the RAM's interior is tastefully done in cloth, even with a more one-piece look to the door panels. Depending on color, the RAM's seats might look a little outclassed to some eyes. In leather, I think the RAM is better executed, mostly because of the multi-colored dash, leather trim, and less seams on the door panels.
Of course, I can't help suspecting that a side-by-side comparison of the interior pieces -- BY THEMSELVES -- with the makers name unattached, might yield vastly different opinions from a lot of people.
Regards,
Dusty
PS- it should look just like this truck but with the Hemi:
http://images.cardomain.com/installs/205000-205999/205928_1_full.jpg
Did you order the automatic? Which auto transmission are they using with the 5.7? What axle ratio will you be getting?
Best regards,
Dusty
I read an article some time back about the manual for the new Hemi RAM. I can't seem to place the piece at the moment, but I think Dodge is developing a totally new manual gear box for the 5.7 engine. I'm sorry, but I can't recall if this is going to be a New Venture unit or from somebody else. I think it's coming from New Venture. I do remember that the development was delayed.
Best regards,
Dusty
Thanks
Keep in mind that despite the peak torque rating, the 5.7 hemi produces over 300 lbs. feet of it at idle speed. I haven't seen a HP curve of the 5.7, but with such a short torque curve I wouldn't be surprised that the HP at 1200 RPM is more than the 5.3 GM.
As to acceleration, the true test is actual time. A seat-of-the-pants comparison can be very misleading. My wife's Avalon at 40 MPH seems like its going much, much faster than my Dakota at 75.
Dusty
Dusty
dusty,
according to a recent news article...dc bought out GM's portion of new venture gear.
radrluv1,
your impressions of the hemi not being particulary fast match mine...but i was driving a regular cab 2500 4x4. i haven't had a chance to test a half ton hemi yet. seat of the pants feel is really hard to judge especially concerning the hemi automatic trucks. the 5-45rfe tranny is so smooth that it almost seems to blunt performance. but, it's a learn as you drive unit so the shifts would prolly "crispin" up over time. i'm gonna have to mosey out to the local lot next week and see if they have any half ton hemis.
for the interior discussion,
imo, without going into long detail, i think the ram currently has the most pleasing interior look and feel of the big three. dodge's dash is definitely better than either ford's or gm's. ford has the acres of plastic look, while gm, despite being better than ford, still reminds me too much of fisher price toys. too many buttons are the light grey colour and feel rubbery! yuck. plus, i'm not sure why, but gm trucks always display too many interior rattles/buzzes and clicks for my tastes...
2wd quad 14/18
4wd quad 13/17
makes one wonder if anyone will want a 4.7l engine in a ram quad cab, doesn't it??
The information I have seen indicates that 89 octane fuel is recommended and 87 octane is acceptable. With mileage in the 13/17 or 14/18 range, the extra 5-10% cost for the 89 octane would be rather significant. What would be the benefit to using 89 octane? Better performance, durability??
Something else about the seat of the pants feel of the 5.7 is that supposedly the drive by wire system pulls out some throttle, on launch and during shifts to keep it smooth, and probably reduce strain on the transmission. I don't know how this will "learn" with driver and break in period. Or if aftermarket will figure out ways to firm up shifts and apply max power possible, but I sure hope so, and soon! Keep in mind that seat of the pants feel is all about torque and gearing too. 350 ft-lbs will accelerate an identical truck equally at 2000 rpm as it does at 4000 rpm. At 4000 rpm though the motor is making twice the HP, still you only feel torque. The advantage of making the torque longer into high rpms, is that you can have that good pull for a long time, and keep the truck in the lower gears (multiplying the torque) longer as well. The real test will be in the 1/4 mile numbers but even the previous 5.9 rams always ran similar times to the 5.3 Chevys in side by side comparison articles, I'd imagine the 5.7 to be a good 1/2 to 1 sec quicker.
funny you should mention the electronic throttle. when i test drove that heavy duty hemi a couple months ago, the throttle feel was odd to me. did indeed feel lazy or slow to register my foot's input. but it did make the truck feel very smooth. it sorta added to the leisurely like feeling that came across during the test drive. all together the ultrasmooth tranny...slow to react throttle and i'm sure mighty heft of the 3/4 ton frame took away some of the "urgency" i had expected to experience. a little throttle tweaking may well help this. and dropping the hemi into a 1/2 ton won't hurt either.
about the tranny, i suspect you are right about them employing some torque management into the computer software. the 5-45rfe is afterall the same tranny that is behind the 4.7l. hopefully they have indeed beefed it up for the hemi and are not just relying on torque management to get by with the hemi!
anyway, the one thing that did really impress me about the hemi was that it idled very smoothly! much more smoothly than any old 360 i've ever driven or riddin in.
I read somewhere that the 545RFE for the 5.7 has been tailored to the engine. I think the input shaft and pump pressures are different.
Dusty
Ford F150 2WD
6 cyl, 4.2 L, Man(5), Regular 17 20
6 cyl, 4.2 L, Auto(4), Regular 16 20
8 cyl, 4.6 L, Auto(4), Regular 16 20
8 cyl, 4.6 L, Man(5), Regular 15 19
8 cyl, 5.4 L, Auto(4), Regular 14 19
Chevrolet C1500 Silverado 2WD
6 cyl, 4.3 L, Man(5), Regular 15 21
6 cyl, 4.3 L, Auto(4), Regular 15 20
8 cyl, 4.8 L, Man(5), Regular 16 20
8 cyl, 4.8 L, Auto(4), Regular 15 19
8 cyl, 5.3 L, Auto(4), Regular 15 19
8 cyl, 5.3 L, Auto(4), Regular 15 19
Dusty
yeah, but the hp/tq jump from the 4.7l to the 5.7l is much more "emphatic" vs the hp/tq jump between the differing gm and ford v8s...that alone will prolly help folks decide to go for the hemi which apparently is nearly as efficient overall as the 4.7l.
since you seem to know about these things...what is the tq rating of the 46re tranny that serves duty behind the 360? the reason i ask is because i found it strange that chrysler is using a lower torque rated tranny (5-45rfe) behind the hemi vs the one behind the 360. i presume the torque rating of the 5-45rfe is lower than the 46re because of the way chrysler names their trannies. the 6 in 46re means it has a higher torque capacity than the 45rfe or 5-45rfe. just found it odd that the hemi tranny wasn't called 5-46rfe or something like that...any input on this?
1st digit = number of forward speeds
2nd digit = torque rating in hundred pounds, feet (minimum)
3rd alpha = (R) rear wheel drive
4th alpha = (E) electronic
Older, non-electronic shift control trannies omitted the fourth character (ie: 44R)
Unfortunately, I've been unable to find out exactly how the 545RFE fits this scheme. I could guess that the first "5" equates to actual number of distinct ranges, but in "Drive" mode only four forward speeds are realized during a normal shift pattern. I've no idea what the "F" would stand for and why the sequence changes if we assume that the "E" stands for electronic.
Some service literature that my dealership had indicated that the 545RFE used with the 4.7 is rated at an input torque of 435 lbs. ft. This should be more than adequate for a 4.7 equiped truck. It should also work with the 5.7 since the max torque rating is 345 lbs. ft., but I would think that a manufacturer would want a little more margin with an engine of that level of power. Then again, my wife's cousin, a transmission tech., indicated once that some other auto trannies don't have much of a margin at all.
I did read that the 545RFE got some changes for the 5.7, a couple I'd already mentioned. I wouldn't be surprised if there were more, although pump pressures probably wouldn't need to change a whole lot since the 5.7 RAM gets the same axle ratio and tire diameter as the 4.7 version.
I seem to recall reading that Chrysler is developing their next generation of high output truck transmissions built around the 545RFE. I've been told that there will be a new RFE-based transmission for the diesel due out soon to replace the 47RE.
Dusty
1st digit = number of forward speeds
2nd digit = torque rating in hundred pounds, feet (minimum)
3rd alpha = (R) rear wheel drive
4th alpha = (E) electronic
THAT'S KINDA WHAT I THOUGHT TOO, BUT IT REALLY DOESN'T WORK...CAUSE THEN THE 46RE (600LB/FT) WOULD HAVE BEEN STURDY ENOUGH FOR THE CUMMINS. INSTEAD DODGE HAS A 47RE TO HANDLE THE LO OUTPUT CUMMINS.
Unfortunately, I've been unable to find out exactly how the 545RFE fits this scheme. I could guess that the first "5" equates to actual number of distinct ranges, but in "Drive" mode only four forward speeds are realized during a normal shift pattern. I've no idea what the "F" would stand for and why the sequence changes if we assume that the "E" stands for electronic.
FROM WHAT I UNDERSTAND, THE 5-45RFE DOES INDEED USE 5 FORWARD RATIOS IN NORMAL DRIVING. THERE IS AN ALTERNATE 2ND GEAR RATIO FOR KICKDOWN (SO REALLY IN TOTAL THERE ARE SIX RATIOS AVAILABLE IN THAT TRANNY RIGHT NOW, BUT ONLY FIVE ARE USED IN A NORMAL SHIFT SEQUENCE). THE WAY I UNDERSTAND IT, DODGE BASICALLY TOOK THE 45RFE THAT WAS INTRODUCED IN LATE '98 AND WAS ABLE TO "PROGRAM" IN ANOTHER OVERDRIVE RATIO FROM THE PLANETARY GEARSET. I DON'T REALLY UNDERSTAND HOW THAT ALL WORKS BUT APPARENTLY THEY COULD ALSO GET MORE RATIOS OUT OF THAT SAME GEARSET IF THEY WANT. I WAS TOLD THIS BY A JEEP TECH.
WHY THEY DIDN'T NAME THE 5-45RFE JUST THE 55RFE I DON'T REALLY UNDERSTAND EITHER. BTW, RFE STANDS FOR REAR WHEEL DRIVE FULLY ELECTRONIC.
Some service literature that my dealership had indicated that the 545RFE used with the 4.7 is rated at an input torque of 435 lbs. ft. This should be more than adequate for a 4.7 equiped truck. It should also work with the 5.7 since the max torque rating is 345 lbs. ft., but I would think that a manufacturer would want a little more margin with an engine of that level of power. Then again, my wife's cousin, a transmission tech., indicated once that some other auto trannies don't have much of a margin at all.
ACTUALLY THE MAX TORQUE OF THE HEMI IS 375 LB/FT. BUT YOU ARE RIGHT, MANY CAR MAKERS DON'T OVERBUILD THEIR TRANNIES. I WISH THEY WOULD!
I seem to recall reading that Chrysler is developing their next generation of high output truck transmissions built around the 545RFE. I've been told that there will be a new RFE-based transmission for the diesel due out soon to replace the 47RE.
LAST I HEARD ON THIS THE HO CUMMINS WILL BECOME AVAILABLE SOON WITH A TRANNY TERMED 48RE. THAT MAKES ME THINK THE 48RE IS STILL BASED OFF THE OLD TRANNY LINE AND NOT THE NEW FULLY ELECTRONIC UNITS...FWIW.
Yes, I did read that Dodge would introduce a "48RE" for the diesel, in fact that was sometime back. It was more recently that I read something about new(er) versions of the 545RFE. I might've been mistaken about that being developed for the diesel, and there was some talk about the 5.7 hemi being punched out to one or maybe two larger displacements. That might explain some beefier versions of the 545RFE.
As I write this the thought occurs that maybe Dodge developed the 545RFE transmission FIRST with a 5.7 hemi or stronger motor in mind, then just used it on the 4.7 when it was introduced.
A friend of mine who's a diehard GM guy recently drove my Dakota, and although he was straining to find something to criticize, did say that the Dakota's transmission was exceptionally smooth and responsive. From this guy that was saying a lot!!
As described to me, the current "R" series is very much an offspring of the earlier A704 and A727 transmissions. There's a fellow on the web that answers auto transmission problems [bjr1a [no_reply@yahoogroups.com] and he has made reference to this a couple of times. Again, a local tech here said that the basic architecture of the current "R" series is very similar to the A704 & 727, with another speed range, overdrive, and electronic shift control added. The A704 & A727s were exceptionally strong and reliable transmissions.
A 48RE should be way more than adequate for the diesel. I know there's been complaints about the 47RE in that application, but most of the troubles that I've read have been shift solenoid related. Of course, I've come to the conclusion that a majority of diesel truck owners are convinced that, just because these are diesel engines, these vehicles should be able to tow 20,000 pounds all of the time.
Dusty
Here is some info from the moparchat web board on Ram transmissions:
Transmission: 545RFE - Automatic Five-Speed
Availability: Optional with 5.7-liter engines
Description: Three planetary gear sets, one overrunning clutch, full electronic control, electronically controlled converter clutch
Gear Ratios:
1st: 3.00
2nd: 1.67 - upshift; 1.50 kick-down
3rd: 1.00
4th: 0.75
5th: 0.67
Transmission: NV4500/NV4500HD - Manual, Five-Speed Overdrive
Availability: NV4500 - standard with 5.7-liter V-8 and 8.0-liter V-10 engines
NV 4500 HD - standard with 5.9-liter standard output I-6 diesel
Description: Synchronized in all gears
Gear Ratios:
1st: 5.61
2nd: 3.04
3rd: 1.67
4th: 1.00
5th: 0.75
Reverse: 5.04
Transmission: 47RE/48RE - Automatic, Four-Speed Overdrive
Availability: 47RE - Optional with 8.0-liter V-10 and standard-output Cummins diesel engine
48RE - Optional with 8.0-liter V-10 and standard-output Cummins diesel engine
Description: Hydraulic control, electronically controlled governor overdrive,
overdrive lockout and converter clutch
Gear Ratios:
1st: 2.45
2nd: 1.45
3rd: 1.00
4th: 0.69
I've seen input torque ratings listed for the New Venture manual transmission on the New Venture web site but I've never seen the automatics listed.
like you said i'm pretty sure the 44re..46re..47re are fairly close decendents of the old torqueflite/727...but from what i heard from the jeep tech the 45rfe/5-45rfe are heavily based on the fwd electronic automatic. as scarey as that sounds, i'm sure the rwd units are much stronger than their fwd brothers...
fyi...here is a cut and paste from daimler media on the 5-45rfe...it certainly appears from this that the 5-45rfe would indeed use five ratios in normal driving...the difference between the 4th and 5th overdrive is so slight that you might not even be able to tell when it goes into 5th...maybe by the tach but prolly not seat of the pants.
TRANSMISSION: 5-45RFE — AUTOMATIC FIVE-SPEED
Description Three planetary gear sets, one overrunning clutch, full electronic control, electronically controlled converter clutch
Gear Ratios
1st__________3.00
2nd__________1.67 — upshift; 1.50 kick-down
3rd__________1.00
4th__________0.75
5th _________0.67