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Comments
Well, I don’t expect a 2.0-liter engine to match the torque output from a 6.0-liter engine. Do you? In RL, the rated peak can be expected to be about 260-265 lb.-ft. Is that lack of torque compared to other engines with similar displacement?
And it is not just the peak torque either, we have been talking “range”. If RL’s engine gets 260 lb.-ft and provides 90% of it (about 235 lb.-ft) or more between 2000 rpm and 6500 rpm, I would say that it is not only high for the displacement, it is also a very broad torque curve!
As for the OHV versus SOHC/DOHC debate, let us use the thread that exists for the purpose.
BMW gets even more horsepower than the RL from a smaller displacement inline in their M3.
RL isn’t supposed to get its peak power at 8000 rpm. Its 300 HP will likely arrive around 6000-6200 rpm range (pretty much where everybody else is rating the peak power these days), and red line at 6800 rpm or so.
That said, it is unfortunate to not see Honda use its engine expertise in high performance sport coupe/sedans. The last time I heard about something along the lines was the NSX GT-R that participated in Honda’s 50th anniversary parade, powered by a 380 HP version of its 3.2-liter V6. This engine was used in Real Time Racing NSX for World Challenge GT Class, before they switched to a supercharged version.
So much for Honda not being able to get “enough” HP/liter out of its engines. :-)
I'm wondering how much VVT actually helps low-end torque?
I’ve a perfect illustration for you. Japanese Accord 24TL (AKA Acura TSX in North America) and American Accord use variations of K24A engine. The dynographs (below) would be helpful.
Honda Accord 2.4
Acura TSX 2.4
Accord’s engine produce 90% of its 161 lb.-ft (about 145 lb.-ft) or more between 2500 rpm and 5800 rpm, while the TSX version produces 90% of its 171 lb-ft (abut 154 lb.-ft) or more between 2000 rpm and 6800 rpm. Obviously, TSX not only has a higher torque curve, but it is broader as well.
The TSX version does have additional tweaks, besides VTEC being applied to intake as well as exhaust side whereas in Accord it is at the intake side only.
That said, the basic idea behind variable valve timing systems is to enhance low-end torque without compromising the same at the top end, and vice versa. It would be possible to get 200 HP out of a 2354 cc I-4 without I-VTEC, but try to imagine the shape of the torque curve.
A basic engine can be tuned to develop most of its torque at low end, and the output will taper off quickly past the mid-range. If you had a secondary cam profile that got activated in the mid-range, the output will stay up in mid range and above (broadening of the torque curve) instead of tapering off.
To understand the impact, superimpose the two versions of Northstar that existed. Northstar used single cam profile, one tuned to produce a little more torque at a lower rpm (300 lb.-ft @ 4000 rpm/DTS) and compromised a little at the top end (rated 275 HP@ 5600 rpm). The other compromised a little at the lower range (295 lb.-ft @ 4400 rpm/STS) to gain a little on the top end (300 HP @ 6000 rpm).
If it were possible to keep the better low end output from the DTS version while retaining the better top end output from STS version, we wouldn’t be talking about compromising one for the other. And that’s where variable timing would come into play.
ksso
Yeah, that's true. But I think that has more to do with the fact that they are working with an I4 engine displacing only 2.4 liters. I know of no other petrol 2.4L that produces significantly more torque without resorting to forced induction.
"I guess if the RL takes the MDX engine and boosts compression ratio to 11.0:1 (which is the same compression ratio as the TL), it may get to 260 ft.lb. We'll have to see."
Everything is speculation at this point. But, unlike the 2.4L I've mentioned, we are now dealing with 3.5 liters in a V configuration. I don't think it is unreasonable to expect a larger boost of more like 10-12 lb-ft with that engine. And there's always the chance that Honda will add something like VTC to the RL's block, which is not found in the MDX, TL, or Pilot.
So, I think 260 or 265 are both reasonable estimates. But my original point was while these peak numbers may come at 4,000 rpms, that does not mean there is no torque in the bottom end.
"At some point, you have to bump up displacement to boost max torque. It looks like multi-stage manifolds help flatten out the torque curve and broaden the powerband, but there is still no replacement for displacement (except supercharging perhaps) when it comes to increasing torque and low end power."
Ultimately, yes, I think you are correct. There is a limit to how much torque can be produced by a given displacement. But what I'm expecting from Acura is a V6 that provides as much torque as the other V6s in this class and horsepower that is closer to the V8s. Assuming the car is priced like the other V6s, how is that a problem?
Not just Honda, just about any engineer is expected to be creative. And why just I-4, you see it in the V6 as well. Don’t you?
No matter what the Honda engineers did to boost power, they're still limited to a max. torque of around 160 ft.lb.
Putting this in perspective, 161 lb.-ft to 171 lb.-ft from a 2354 cc engine is quite good. And especially considering that at least 90% of the peak torque is available for a range of (almost) 5000 rpm!
Do you not agree?
We're making a big deal out of getting the torque curve as flat as possible and as low down the powerband as possible, saying things like "90% of peak torque available at 2,000 rpms." But still, 90% of 160 ft.lb. is only a measly 144 ft.lb. of torque.
So, are you suggesting that it is better to not have a flat torque curve from an engine producing 160 lb.-ft? For that matter, any engine regardless of the output?
At some point, you have to bump up displacement to boost max torque.
Undeniable fact. But, how is it better to increase displacement every time torque has to go up? To put this in perspective, for couple of years, a version of Honda 3.5/V6 produced 229lb.-ft. In case of RL, we’re now “talking” 260 lb.-ft. Should Honda have bumped up the displacement to almost 4.0-liters to achieve 260 lb.-ft? To me, it appears, engineers managed to get more from the same and I can never associate that with being a bad idea. Technological advancement is the obvious answer!
Now, if we were talking 300 lb.-ft or more, I don’t see how a normally aspirated 3.5-liter engine could achieve that, in which case, the displacement will have to be bumped to 4.0-liter or so (a “really good and efficient design” typically gets about 75 lb.-ft per liter displacement), unless the efficiencies of the engines suddenly changes. Even in racing forms, the engines are barely hitting 90 lb.-ft per liter at max.
Generally the replacement for displacement is better breathing and better breathing via some form of forced induction seems to be very effective and very efficient. Further gains can be achieved via ultra high compression ratios (12:1, e.g.) and direct (or fuel stratified) injection. The technical tricks that are coming soon to an engine near you are quite impressive.
And, we've also talked about the max torque available @ 0 RPM's of an electric DC motor -- the main reason for the low down torque, as noted herein by severl of us, is off the line acceleration (perhaps [improving] the 0 - 62 sprint is enough [of a range] that the assist could be kept, mainly, to achieve that goal).
In any case the "new" Acura/Honda 3.5L with twin turbos and enough "beefing up" to make reliability not an issue, would get them where they "want" to be with little fuss or muss. Torque would jump impressively and HP should surpass 400HP, which in the RL ought to be plenty for both bragging rights and absolute performance and efficiency.
I know, "not gonna do it," "wouldn't be prudent."
I can dream, can't I?
Yes, I don't think their is an ultimate limit to how much torque can be provoked from a given displacement. In the year 2025 someone may find a way to get 110 lb-ft per liter. The envelope is always being pushed. The goal posts are always moving farther away.
I think the trick in speculating about the RL is trying to "keep it real". We do that by guessing within the parameters of what Honda is already capable of doing today. Hence all this discussion about other Honda engines.
All this makes me wonder how the others will respond. It's all fun and games to compare numbers like this, but it's the market that will determine how much power is needed. Maybe people won't care about the RL's horsepower advantage. Or maybe the others will be forced to adjust their 6 cyl offerings in either price or output.
Yes, that's exactly my point. I'm not denying that Honda is great at doing a lot with a little, but this is America, the land of no displacement taxes.
Why can't Honda just bump up displacement and use its VCM technology so that we can get both power and decent gas mileage?
Lets say Engine A is pumping 400 lb-ft of torque max, at 4500 rpm, and 120 lb-ft at 2000 rpm
Enginge B is pumping 250 lb-ft of torque max at 4200 rpm, and 180 lb-ft at 2000 rpm
Obviously engine 2 is better in my dishonest opinion.
Not disagreeing with you, but who says the best technology needs to be used on smaller, less powerfu engines? Why not use the same technology on the bigger engine and get the same flat torque curve?
The RL is supposed to be Honda's flagship. I can't see Honda skimping on the technology front for the RL's engine.
As the car speeds up and the gearing controls where the car can keep in the powerband, you are good to go. If you still can't get your car moving fast, one of two is likely, you either are incapable of shifting your gears if its a manual or if it's an auto, the computer controlling the shift points was just designed by morons and that car company needs to shutter down yesterday!
But in city driving, you're going fro 0 to 40 mph A LOT. The fact is, unless you're racing, low end grunt is usually a lot more useful than high revving HP. Also, isn't the RL supposed to be a luxury car, not a sports car? This class of car is supposed to have low end grunt so that you can accelerate smoothly without making the engine scream, which is bad for NVH, an important consideration in luxury cars.
Non-VTEC OHV engines with multi-intake manifolds such as GM's LSv8s and DC's Hemi hit 90% peak torque at 2,000 rpms. The DOHC I4 in the Accord has 161 ft.lb. and 160HP, the higher compression version in the TSX gets 166 ft.lb. and 200HP. A pretty minimal increase in torque, but a significant increase in HP.
By comparison, the only OHV engine with both VVT and dual-intake manifolds hits 90% peak torque at 1,800 rpm, so it seems like VVT accounts for approximately 200 rpms.
With the addition of VTC, Honda is working out how to correct for problems with a smooth power curve. The addition of VTC is yet another way to manage air flow which can compliment VTEC. The combination is called i-VTEC in Honda speak. All three of the 2.4L engines I mentioned earlier use i-VTEC to produce what is essentially a very broad torque curve for an I4 engine. I mean, the torque curve for the TSX's I4 doesn't look as good as BMW's I6, but it's pretty darn impressive for a 4 banger.
I'm familiar with VTC and i-VTEC and I agree it flattens the torque curve and Honda's 4 bangers are impressive for a 4 banger, but it's still a 4 banger.
Enthusiasts (like us) aren't representative of the average car buying public IMO. We LIKE to rev that engine and blast it, but seriously, most people don't and the high end HP just ends up becoming a marketing ploy.
I never complained about Honda's specific output. I am merely pointing out that no matter how good the specific output, the TOTAL OUTPUT is not that high with limited displacement.
Accord’s engine produce 90% of its 161 lb.-ft (about 145 lb.-ft) or more between 2500 rpm and 5800 rpm, while the TSX version produces 90% of its 171 lb-ft (abut 154 lb.-ft) or more between 2000 rpm and 6800 rpm. Obviously, TSX not only has a higher torque curve, but it is broader as well.
The TSX version does have additional tweaks, besides VTEC being applied to intake as well as exhaust side whereas in Accord it is at the intake side only.
I think your numbers are off b/c the TSX only gets 166 lb-ft. Wouldn't you agree that all the extra tech. in the TSX engine is producing a pretty paltry return in terms of extra torque?
I agree that VTEC can help broaden the torque curve, but how much is it really helping? OHV engines w/o VTEC have just as broad and flat a torque curve.
That said, the basic idea behind variable valve timing systems is to enhance low-end torque without compromising the same at the top end, and vice versa. It would be possible to get 200 HP out of a 2354 cc I-4 without I-VTEC, but try to imagine the shape of the torque curve.
Isn't that another way of saying VTEC helps increase max. HP at higher RPMs? If you start off with an engine that has good low end torque and add VTEC, it helps raise the HP. If you start off with an engine that has high HP but a non-flat torque curve, VTEC can help flatten the torque curve.
I'm aware of how VTEC works, and I think we're all using different words to say the same thing.
But no matter how good VTEC is, it can't make create torque where it doesn't exist. Look at the TSX engine vs. the Accord I4, all that extra VTEC raises max. torque by 5 lb-ft.
First, it's not 171 lb-ft, it's 166. Second, the 5,000 rpm range (covering from around 2,000 rpms to around 7,000 rpms) is misleading. The rpm range from at least 5,000 rpms to 7,000 rpms are unusuable, so who cares?
You think Honda automatic trannies aren't going to upshift by 4,500 rpms? And you'd have to want to waste your engine pretty bad if you're going to upshift at 5,000 rpms regularly in a manual.
So, are you suggesting that it is better to not have a flat torque curve from an engine producing 160 lb.-ft? For that matter, any engine regardless of the output?
You're missing the point again. I'm saying no matter how flat the torque curve, 160 ft-lb is not a lot. It's appropriate for a small car like the Civic USED to be.
With the Civic and Accord getting larger, and the CR-V being an SUV, that 4 banger is really straining, especially with a full load.
how is it better to increase displacement every time torque has to go up? To put this in perspective, for couple of years, a version of Honda 3.5/V6 produced 229lb.-ft. In case of RL, we’re now “talking” 260 lb.-ft. Should Honda have bumped up the displacement to almost 4.0-liters to achieve 260 lb.-ft? To me, it appears, engineers managed to get more from the same and I can never associate that with being a bad idea. Technological advancement is the obvious answer!
Sometimes technology can provide the answer and sometimes it doesn't. Witness all the extra technology in the TSX I4 for a measly 5 lb-ft. increase in max. torque. Also, adding more tech can add costs, reduce reliability and raise repair costs.
Besides, this is not an either/or situation. I'm not advocating ditching the tech and going with displacement only. Why can't Honda offer more tech and more displacement? The U.S. doesn't have silly and artificial displacement taxes like Europe and Japan do.
Let us assume we have engine A that is tuned for low-end power. The fixed cam profile isn’t going to be able to do much in the top end, resulting in lower peak power.
We want to develop engine B, using engine A, but now we want more peak power. We don’t have a choice, but to use a fixed cam profile. This time, we choose to compromise some low-end power in favor of letting the engine breathe better at higher rpm, hence producing higher peak power than in engine A. Mission accomplished.
To put this in real life, that GM’s 4.6/V8 used in DTS (275 HP) can be considered engine A, and the STS version (300 HP) would be the engine B. To get the additional 25 HP, GM engineers seem to have fiddled with the single cam profile that was available and forcing the engine to breathe better 400 rpm higher (peak torque moved from 4000 rpm to 4400 rpm and peak power moved from 5600 rpm to 6000 rpm).
If something like first generation VTEC were to be used, we could start with engine A, the basic cam profile tuned for low-end power. After 4000 rpm, the torque output would taper off. But now, VTEC provides us a second cam profile that will take over, and push the torque curve back up again and help deliver greater peak power.
A: 120 HP @ 5200 rpm, 125 lb.-ft @ 4000 rpm (90% of peak torque available at 2000 rpm)
B: 140 HP @ 5500 rpm, 140 lb.-ft @ 4500 rpm (90% of peak torque available at 2500 rpm)
Does this mean engine B lacks low-end torque compared to engine A since “90% of peak” arrives 500 rpm later? A simple math reveals that engine B produces 126 lb.-ft at 2500 rpm, which is greater than the peak torque from engine A!
At 2000 rpm, engine A will be producing 113 lb.-ft, and unless engine B has a real lousy torque curve below 2500 rpm, it is likely producing better than 113 lb.-ft.
To use real examples, let us use couple of Honda’s V6 engines.
C35A: 225 HP @ 5200 rpm, 231 lb.-ft @ 2800 rpm (3.5/V6 in current RL)
J35A: 265 HP @ 5800 rpm, 253 lb.-ft @ 3500-5000 rpm (3.5/V6 in current MDX)
I have not seen dyno plot for the C35A, but let us assume the engine produces 95% of its peak torque at 2200 rpm. And that would mean
About 220 lb.-ft at 2200 rpm
Peaks at 231 lb.-ft at 2800 rpm
Tapers just a little to 227 lb.-ft at 5200 rpm (to develop 225 HP).
This engine doesn’t use VTEC, so it is using a single (fixed) cam profile, but has a reasonably flat torque curve (between peak torque and peak power engine speeds which are 2400 rpm apart, the torque output is dropping by only 4 lb.-ft).
OTOH, this dyno plot for J35A suggests that the engine develops
300 Nm (220 lb.-ft) at about 1200 rpm!
By 2000 rpm, the engine is developing about 235 lb.-ft (which is already better than the peak in C35A)
Continues to develop more until hitting the ceiling at 3500 rpm (253 lb.-ft) and maintains the peak for next 1500 rpm
And, finally, starts to taper off to 240 lb.-ft (still 95% of its peak torque) at 5800 rpm.
While J35A also appears to hit its “95% of peak” mark at about 2200 rpm (about 325 Nm/240 lb.-ft), retaining this 5% over a range of engine speed from 2200 rpm to 5800 rpm is far more impressive because it is harder to maintain a higher percentage of high specific output than it is to maintain the same percentage of lower specific output.
To put this in “numbers”,
C35A has a maximum specific torque output at 66.5 lb.-ft per liter compared to 72.9 lb.-ft per liter for the J35A. 95% (or 90% or any percentage) of 66.5 lb.-ft per liter would be easier to retain compared to the same for the 73 lb.-ft per liter engine.
J35A ends up producing more HP because it has a broader torque curve that continues to hold itself past the magical 5252 rpm mark in the formula
HP = Torque (lb.-ft) * Engine Speed (rpm)/ 5252
If, instead of producing 240 lb.-ft at 5800 rpm, the J35A were producing 226 lb.-ft, then the engine would be rated as 250 HP @ 5800 rpm, 253 lb.-ft at 3500-5000 rpm! But since it develops more torque, it ends up developing 265 HP.
The same will be true for RL, which will have to have its torque curve just a little higher and just a little wider, to get the additional 35 HP.
Heh.
Everything is speculation at this point. But, unlike the 2.4L I've mentioned, we are now dealing with 3.5 liters in a V configuration. I don't think it is unreasonable to expect a larger boost of more like 10-12 lb-ft with that engine. And there's always the chance that Honda will add something like VTC to the RL's block, which is not found in the MDX, TL, or Pilot.
Making the RL's engine an i-VTEC might do the trick, but I'm not sure the extra displacement will necessarily improve incremental gains.
For example, the 2003 TL Type-S had a 3.2L SOHC v6 making 260HP@6,100rpm and 232 lb-ft@3,500 rpm with a compression ratio of 10.5:1.
Boosting the compression ratio to 11.0:1 in the 2004 TL raised HP to 270HP@6,200 rpm (have to rev 100 rpms higher for the extra 10HP) and 238 lb-ft@5,000 rpm (an extra 6 lb-ft @ 1,500 rpm more is not that great an incremental gain).
So, I think 260 or 265 are both reasonable estimates. But my original point was while these peak numbers may come at 4,000 rpms, that does not mean there is no torque in the bottom end.
Oh I agree. Assuming 260 torque and 90% peak at 2,000 rpm, that's 234 ft-lb at 2,000 rpm which isn't bad. As long as the RL isn't too heavy, it'll probably be enough.
Well, I’m going by the official plot (232 Nm or 23.7 kg-m or 171 lb.-ft, pick your unit of measurement).
Second, the 5,000 rpm range (covering from around 2,000 rpms to around 7,000 rpms) is misleading. The rpm range from at least 5,000 rpms to 7,000 rpms are unusuable, so who cares?
How the heck is availability of 90% of peak torque from about 2000 rpm to 6800 rpm “misleading”? If you need to look at the dyno, again, here it is.
You think Honda automatic trannies aren't going to upshift by 4,500 rpms? And you'd have to want to waste your engine pretty bad if you're going to upshift at 5,000 rpms regularly in a manual.
You can rev to red line (7100 rpm) in Sport Shift mode (and of course, manual mode) in TSX. And being a Honda engine, you can do it regularly, as often as you need 200 HP to move around!
I'm saying no matter how flat the torque curve, 160 ft-lb is not a lot. It's appropriate for a small car like the Civic USED to be.
Not really. 160 lb.-ft in a 3000-3200 lb. car with decent gearing is more than enough for all practical purposes. I drive a 3200 lb. car with 152 lb.-ft (peak torque), and I rarely need to get to or past the peak torque point. In fact, nearly all of my driving occurs under 3000 rpm.
Sometimes technology can provide the answer and sometimes it doesn't. Witness all the extra technology in the TSX I4 for a measly 5 lb-ft. increase in max. torque.
Compared to the other engine, that uses similar technology? And the extra tweaks that TSX engine receives over Accord I-4 does not necessarily involve a much higher peak, rather, a much broader torque curve. I though I had already stated that and backed it up with pictures.
Also, adding more tech can add costs, reduce reliability and raise repair costs.
I would rather drive a late model Supra with its 3.0-liter I-6 pumping 225 HP, than the 1982 Supra I had with its 2.8/I-6 pumping 145 HP. Which would you prefer? I couldn’t speak of cost and repair costs. Never have been involved in anything major (having owned only Toyota and Honda vehicles). So, reliability is the only thing I’ve experience with.
Why can't Honda offer more tech and more displacement?
Balancing the Needs versus Want would be my guess. To get the real picture, we need to ask Honda.
Also, you have to remember that most cars are economy cars and are tuned for low end power and low rpm idle quality. So for the majority of cars, VTEC didn't do much to help their low end torque, it just raised their high end HP. So the statement that VTEC raised high-end HP is NOT a myth to most car owners.
Also, we're saying the same things about VTEC. There is NO difference between the following statements:
1. VTEC raises high end HP on an engine tuned for low end torque.
2. VTEC improves low end torque on an engine tuned for high end HP.
3. VTEC helps an engine achieve both low end torque and high end HP.
OK. Shoot Acura an email then and let them know that the specs listed on the TSX on their OFFICIAL website are wrong.
How the heck is availability of 90% of peak torque from about 2000 rpm to 6800 rpm “misleading”?
It's misleading b/c most people rarely, if ever, rev their engines beyond 5,000 rpms. So having 90% of the torque band available from 5,000 rpm to 6,800 rpm is NOT worth much. If it ain't gonna be used, who cares if it's there?
You can rev to red line (7100 rpm) in Sport Shift mode (and of course, manual mode) in TSX. And being a Honda engine, you can do it regularly, as often as you need 200 HP to move around!
But most people get automatic trannies. And they'll never use the powerband above 4,500.
Also, I have no stats, but I doubt that most people with manual trannies rev it much past 5,000 rpm either. The FACT that you can do something doesn't mean it's done.
How often do you rev it to 7,000 rpm?
Also, remember we're talking about the RL, a luxury car here. You think luxury car buyers are going to thrash their vehicles at 7,000 rpm often? I doubt it.
Not really. 160 lb.-ft in a 3000-3200 lb. car with decent gearing is more than enough for all practical purposes. I drive a 3200 lb. car with 152 lb.-ft (peak torque), and I rarely need to get to or past the peak torque point.
Shorter gearing can make up for lack of torque and displacement, but it also comes with a penalty in gas mileage.
I get 13 mpg on my MDX in city driving b/c it doesn't have enough power to move a vehicle that heavy, so the gearing is short.
With more displacement and torque, the MDX could have taller gearing (especially in first) to get better city gas mileage, and then use DoD to maintain the v6 highway gas mileage.
In fact, nearly all of my driving occurs under 3000 rpm.
Doesn't that prove my point that broadening the torque band beyond 5,000 rpm is a waste of technology. Who cares what happens to the torque band beyond 5,000 rpm unless you're planning to drag race.
I would rather drive a late model Supra with its 3.0-liter I-6 pumping 225 HP, than the 1982 Supra I had with its 2.8/I-6 pumping 145 HP. Which would you prefer?
This is meaningless statement. No 20 year old engine will compare with modern engines.
I couldn’t speak of cost and repair costs. Never have been involved in anything major (having owned only Toyota and Honda vehicles). So, reliability is the only thing I’ve experience with.
If you ever worked on engines, you'd know how much some of those high-tech parts cost, how difficult they can be to package, and your preferences might differ.
Just at a hair south of $50K.
OK, now this seems to be a, um, er, shall we say somewhat less refined car than the RL. But, perhaps this car is a condender too. I had thought the A6 3.2L (and maybe the 300C AWD) and the Cadillac STS AWD would be. Recently, I have come to think the field had narrowed to the Audi and the Acura -- I have never driven one of these Volvos, but when my Audi was in for the On*star regrooving last week, I had a brand new S40 loaner for two days -- it was pretty nice (literally brand new enterprise rental car that the Audi dealer gave me).
So, I see this S60 Type R all zooted up and I wonder if anyone other than I has even considered this Swedish dish (couldn't resist the double ish).
But they also must balance that with their use of FWD architecture and goal of producing clean efficient cars. A big, heavy, large displacement engine is more difficult to work into that paradigm than a more modest sized block. Sure the Hemi engines supply abundant torque. But they also require a tractor trailer of a body to support them. They need that torque to make it move.
"...who says the best technology needs to be used on smaller, less powerfu engines? Why not use the same technology on the bigger engine and get the same flat torque curve?"
Well, I think that's because little engines need it. I4 designs are great for efficiency, but they have peaky outputs. A V6 configuration has a much broader power curve. There is less need to tweak it. An I6 has an even broader curve.
So, for a vehicle like the Pilot or Odyssey, there is little need to spend lots of money on expensive engine technology for benefits that would be lost on the average customer. 3.5 liters with a basic VTEC curve is enough for the market.
Now, the RL is a different story. At this price point, the little things add up to big bucks. So, yes, I do expect that Honda will pull out some stops. Whether it comes in the form of an i-VTEC base engine, or an IMA hybrid, or a VCM system I cannot say.
"The fact is, unless you're racing, low end grunt is usually a lot more useful than high revving HP. Also, isn't the RL supposed to be a luxury car, not a sports car? This class of car is supposed to have low end grunt so that you can accelerate smoothly without making the engine scream, which is bad for NVH, an important consideration in luxury cars."
Yes, and no. The new RL is not meant to be a luxo-barge. It appears to be competition for the sportier versions of the large sedans. In short, the GS300, not the LS430. Good low end torque is a requirement, but as witnessed by the 80% percent who buy V6s in this class, it is not required that the vehicle have ultimate low-end torque. There is such a thing as good enough.
And NVH is a good reason for using the smaller engine. The less reciprocating mass you have churning under the hood, the less you have to add in order to silence it.
Sometimes technology can provide the answer and sometimes it doesn't. Witness all the extra technology in the TSX I4 for a measly 5 lb-ft. increase in max. torque. Also, adding more tech can add costs, reduce reliability and raise repair costs.
You're comparing an i-VTEC engine against another i-VTEC engine. Of course they are similar. The differences in complexity between the two are not remarkable. Given the mission of the TSX, I would think that it's obvious why they would chose to boost HP rather than torque. It's not a tractor. Torque was not the goal.
"Boosting the compression ratio to 11.0:1 in the 2004 TL raised HP to 270HP@6,200 rpm (have to rev 100 rpms higher for the extra 10HP) and 238 lb-ft@5,000 rpm (an extra 6 lb-ft @ 1,500 rpm more is not that great an incremental gain)."
Is that by design? Is it possible that they could have boosted torque even higher if they wanted to? They might have added VTC for example. Is it possible they opted not to do that for some reason? A reason like, say, torque steer?
It looks like you have entered a 'circular argumentation' of the academic type, and according some less happy outcomes of such activities it looks like the same numbers give raise to totally opposed views.
Gladly I have seen that you are converging a bit and I plaude both for the effort!
On the merit of what you have said there is little to add, wonderful and clear review of available data but please let me remind you that in most cases 'bragging rights' are not build on such sophisticated profiling of technical specs. Marketing goes on and on on Max outputs and the 'test drive' takes care of defining one affinity for one rather than another offering out there on the market.
in adition, I had shortly mentioned before that numbers are great but rarely do justice when the end point is concerned. To support my philosophy I had described a 350 miles trip on I-4 equipped Accord and attempted to communicate that a passenger not acquainted with honda vehicles and driving a high output all american V6 FWD model was enthused to fell how much the Accord was feeling to him like a V6 powered vehicle.
To address and connect to some of your technical comments I would also like to reiterate and address some of your statements.
the 5,000 rpm range (covering from around 2,000 rpms to around 7,000 rpms) is misleading. The rpm range from at least 5,000 rpms to 7,000 rpms are unusuable, so who cares? etc..........
I can side with you but for all the wrong reasons. In fact, if I can drive at 100 mph with the engine at 3.2 k rpm I barely see any need to get any higher than that! So indeed from a practical everyday driving (and beyond) there is not compelling reason to dwell in that discussion other than an academic interest and the pursuit to establish comparable entities in comparing engines/vehicles. Now reversing gear and perusing the tech aspects, after agreeing with the falt torque curve genarl arguments, I would rather prefer an engine that has adequate torque/response at low rpm but goes up midrange and keeps increasing toward redlining because that profle best cope with the limitations imposed by the quadratic nature of resistance in relation to vehicle speed (that is the real word event that is responsible for sipping out all that power that the engine can give). Endgame would be that you would have better responsiveness when passing vehicles on the highway while still having adequate skidpad performance!
I guess I wold treat any other point of your controversy in similar fashion so you can guess my comments.... ultimately when I will choose my next vehicle I'll look into general characteristics and than drive to decide if that vehicle is as responsive, fast and fun to drive as I desire it to be!! AND I SHOULD STRESS THAT "I" because it does not need to be the fastest or the most powerdul or the biggest but just THE MOST FUN FOR ME!
OK, sorry if I was a bit loud here! After all these are just opinions.
Good point. FWD limits engine sizes.
A big, heavy, large displacement engine is more difficult to work into that paradigm than a more modest sized block. Sure the Hemi engines supply abundant torque. But they also require a tractor trailer of a body to support them. They need that torque to make it move.
It's a myth that OHV v8s are large and heavy. GM's 5.7L OHV v8 LS1 will fit easily into a BMW 3 series. Check out this link.
http://www.vorshlag.com/ls1bmw1.asp
In contrast, it's much harder to stuff BMW's 5.0L DOHC v8 from the M5 engine. Check out this link.
http://www.caranddriver.com/article.asp?section_id=4&article_- id=3485
The Hemi is a big engine, but it still fits into cars, something that can't be said for a comparable displacement OHC v8.
In any case, Honda isn't going the OHV route so they're stuck with trying to package bigger OHC engines into FWD cars. I still think they can up the displacement a little and still fit the engine into the bay.
You're comparing an i-VTEC engine against another i-VTEC engine. Of course they are similar. The differences in complexity between the two are not remarkable. Given the mission of the TSX, I would think that it's obvious why they would chose to boost HP rather than torque. It's not a tractor. Torque was not the goal.
It's a valid point, but look at the CR-V. That is clearly a car that needs more low end torque than high end HP and Honda tuned it accordingly and they're still stuck at around 160 ft-lb (162 ft-lb@3,600 rpm to be exact).
I really don't think tuning is the reason why the torque is stuck at around 160 ft-lb. I think Honda has hit the limits of its engineering and now they need to bump up displacement for more torque.
Boosting the compression ratio to 11.0:1 in the 2004 TL raised HP to 270HP@6,200 rpm (have to rev 100 rpms higher for the extra 10HP) and 238 lb-ft@5,000 rpm (an extra 6 lb-ft @ 1,500 rpm more is not that great an incremental gain).
Is that by design? Is it possible that they could have boosted torque even higher if they wanted to? They might have added VTC for example. Is it possible they opted not to do that for some reason? A reason like, say, torque steer?
It's possible that Honda could go higher and chose not to due to torque steer, but given their inability to do much with the I4, I think they did as much as they could.
Mark, what is new on the 60 R for '05? Is it enough to justify a 13 THOUSAND dollar hike? Last time I checked S60 Rs were like $38K. I can only give you my impressions of the first gen S60 R. It is fast for a Volvo (0-60 is in the mid to high 5s I think) but I did not like the feel of the 5 cylinder. I hated the Vigor's 5, and I have never liked any Volvo 5. Volvo says its more "flexible" than an standard six. Whatever guys. If a 5 cylinder engine was in any way superior to a 6, somebody besides Volvo would be using them. The engine just feels unrefined. Not in a good throaty, raspy way like the VQ, just noisy, and when the revs climb to peak, it gets VERY noisy. It sounds like a small displacement, overly boosted attempt (which it basically is) to try and compete with real performance engines like C32AMG, M3, S4, etc. (which it definitely does NOT).
Mark, your clearly a performance 1st guy, so honestly Im surprised you'd even give the Volvo a second glance. The Four-C AWD\active chassis thing is a "nice try" compared to the big boys, but thats as far as I'd go. Its first and foremost a Volvo, and tail spinning fun is not "safe". For its $40K asking price it was hard to argue with, as that undercuts even the CTS-V. (I have little doubt the Cad would destroy it on a track though). But if Volvo thinks its worth $50K, unless they've made some serious changes, I just have to laugh.
GM is making a 5 cylinder engine for its light trucks, the Colorado.
Re turbolag, here's what How Stuff Works says about it:
http://auto.howstuffworks.com/question122.htm
One of the main problems with turbochargers is that they do not provide an immediate power boost when you step on the gas. It takes a second for the turbine to get up to speed before boost is produced. This results in a feeling of lag when you step on the gas, and then the car lunges ahead when the turbo gets moving.
I've experienced turbolag in every supercharged car I've driven.
"Holy crap guys lighten up a bit
Well said Lexusguy! The dialogue has been extremely informative, but, frankly, a little over my head. All I can say...the new RL better do 0-60 in the under six second range, top end at 150+ MPH, be quiet, be well appointed, handle superbly (which SH-AWD promises), get decent mileage, feels "solid", and gets comments from my passengers to the effect, "...Hey this is really nice, what kind of car is this?" - If it meets the aforementioned criteria...I'll be a happy camper!
Now regarding your issue with engine speeds beyond 5000 rpm rendered “useless”, I don’t think so. If you think it is, why do you admire cars that have more than 200 HP (assuming 200 HP can be assumed to be “good enough”)? Do we really need 400-500-600 HP cars?
VTEC is being used for more than improving power output, however (it would be wrong to assume that it improves power only at the top end). It has been used to improve emissions, fuel economy (VTEC-E, and most recently, I-VTEC-I) and cylinder deactivation systems (“Cylinder Idling System” in Civic Hybrid and “Variable Cylinder Management” in Inspire and upcoming Odyssey/Accord Hybrid).
Regarding Acura’s rated 166 lb.-ft versus Honda’s dyno plot, I could care less. If you have an official plot that shows 166 lb.-ft, we will use it. That said, if TSX does get 166 lb.-ft and chassis dyno reads 155 lb.-ft at the wheels, that would make for one heck of an efficient drive train, with less than 7% drive train loss.
It's misleading b/c most people rarely, if ever, rev their engines beyond 5,000 rpms.
How is that misleading? Is it misleading to quote 500 HP from an engine if most people don’t use it (and definitely don’t need it)?
But more importantly, you should be able to associate engine’s power and torque characteristics using its gearing. 5000 rpm in car A doesn’t necessarily have the same effect as 5000 rpm in car B.
But most people get automatic trannies. And they'll never use the powerband above 4,500.
I do.
How often do you rev it to 7,000 rpm?
My car’s engine (unfortunately) red lines at 6300 rpm. My Prelude’s engine redlined at 7400 rpm and it used to be a pleasure to see it sing. But, to talk about revs, you have to understand the concept of power, torque and gearing first. And we can do it outside of this thread.
With more displacement and torque, the MDX could have taller gearing (especially in first) to get better city gas mileage
More displacement wouldn’t need more air, as a result, more gas to combust it?
Yeah, I think that about sums up my perspective. If the RL's 3.5 generates around 260 lb-ft and VTEC breathing allows it share that torque across a wide rpm range, it'll be just fine.
Lemme see if I can stir up another controversial topic to get us off this engine business...
Ah, here's one. The trunk lid!
I keep seeing posts opining that the RL's rear deck looks like the nasty two-pieces-of-clay-mashed-together look of the BMW 7 Series. I just don't see it myself.
I mean, yes, the trunk is raised above the level of the rear fender, but it's not styled the same. At least, not any more than the raised decklid on every Volvo sedan. The closest comparison I've found is actually the Hyundai Elantra. With the Elantra, the merge is much more tasteful and it really does make a difference.
With the Acura RL, the fender is already headed toward the point where the decklid meets it. The transition is fairly smooth.
That isn't true with the 7 Series. The transition is more abrupt and the 7 Series has that big faux spoiler built into the trailing edge to call attention to how much higher it is compared with the fender.
JM2C
I did forget about GM's 5, but in a pick up truck you can get away with a lot more NVAH. In a $40K (or now $50K) luxury sedan, its inexcusable.
Humps have never really been in fashion, in fact, they have often been reviled and rejected. For example, take the Humpback of Notre Dame. Didn't do him much good, did it? Or consider what happened to Humpty Dumpty ... well, we all know that he took a great fall and the best body shop in the kingdom -- KINGSMAN Auto Body -- couldn't put him back together again. (they had to "total" him 'cuz he leaked a lot of fluids)
Camels have humps, but, they do not exactly cut the form of a graceful gazel, now do they? And worse, they spit at you!
Or, take the case of Hubert Humphrey. A very nice, conscientious man, but he couldn't get elected as President, now could he? He went on the stump and just took his lumps!
Sir Bangle of BMW (that has a ring to it) seems to have started this hump thing anew, and now look what's happened -- the medical term is: Humpus backus car-assus.
No, gentlemen, I think humps are for chumps.
MEMO to ACURA: DUMP the HUMP!
i actually like the 7 and 5 series rears, MINUS the lights.
i think the z4 looks ridiculous, but i actually like the 7 & 5 minus the rear tail lights.
but then again, Acura is growing up and BMW is growing old.... senility is a dangerous thing... i'm glad we bought the wife's 3series convertible last year rather than wait to see the brand go downhill....
ksso
Probably. I posted a link earlier to an upclose PR picture earlier. Here it is, again.
I've already said the same thing twice previously.
Now regarding your issue with engine speeds beyond 5000 rpm rendered “useless”, I don’t think so.
I said flattening a torque curve beyond 5,000 rpms is useless, not engine speeds beyond 5,000 rpms are useless. Different subjects.
VTEC is being used for more than improving power output . . .
I know all about VTEC and i-VTEC, how it works and what it does. My bro is a mechanic and he tunes modded Honda Civics all the time for the teenagers around here, and I've helped him slap on blowers, nitrous, bigger cams, bored out blocks for more power, etc.
How many VTEC engines have you worked on?
Regarding Acura’s rated 166 lb.-ft versus Honda’s dyno plot, I could care less.
Like I said before, take it up with Acura, not me. It ain't my numbers. Acura's official website lists the TSX at 166 ft-lb. What's your beef anyway? We're talking about a 5 ft-lb difference. Who cares?
But most people get automatic trannies. And they'll never use the powerband above 4,500.
I do.
First, my above bolded statement is still true. Most cars are sold with auto trannies and torque above 4,500 rpm is going to be useless to those people.
Second, you changed your position (again) because in post #1473 you said:
"In fact, nearly all of my driving occurs under 3000 rpm."
But, to talk about revs, you have to understand the concept of power, torque and gearing first.
Oh I fully understand these concepts. I'm not sure you do, however, based on your following comment.
More displacement wouldn’t need more air, as a result, more gas to combust it?
Let me make an analogy here. A big displacement engine is like a weightlifter. Weightlifter eats a minimum of 10 gallons of gas and can lift 100 lbs. over his head.
A small displacement engine is like a sprinter. Sprinter consumes a minimum of 1 gallon of gasoline and can lift only 5 lbs. over his head, but he can do so frequently and very fast.
Scenario A: 10 lbs. must be lifted. The weightlifter consumes 10 gallons of gasoline to lift the 10 lbs. The sprinter consumes 2 gallons of gasoline to lift 5 lbs twice, for a total of 10 lbs.
In scenario A, the sprinter is more fuel efficient. The weightlifter is overpowered for the task of lifting just 10 lbs.
Scenario B: 200 lbs. must be lifted. Weightlifter chugs 20 gallons of gas and lifts 100 lbs. twice, for a total of 200 lbs. Springer sips 40 gallons of gas and lifts 5 lbs. 40 times.
In scenario B, the weightlifter is more fuel efficient because his full power can be utilized.
The MDX is a big and heavy car, and my gut feeling is that the Weightlifter will be more fuel efficient than the Sprinter. More displacement means more low end torque, can have taller first gears and better fuel efficiency.
MEMO to Acura: Hump the competition...
I'd have to disagree with you there. Torque in the high rpms produces more horse power (ability to do work over time) than torque in the lower rpms. For example, 5 lb-ft @ 2,000 rpms is worth only 1.9 hp. While 5 lb-ft @ 5,000 rpms is good for 4.7 hp. The higher you go in the RPM band, the more power is generated with the same amount of torque.
As an all-too-often-posted link describes it, "It's better to make torque at high rpms because you can take advantage of gearing".
As for the RL, most speculate that the car will tip the scales between 3,700 and 3,800 lbs. So the need for gobs of torque is not as great as it would be in vehicles like the Pilot and MDX, which weigh in north of 4,200 lbs.
Regarding panel gaps...
Yeah, what's up with that? It looks like the gaps between sheetmetal are fine, but the gaps between plastic lenses and sheetmetal are always larger. Anybody have a theory on why? Does the plastic expand and contract more than sheetmetal? I know it does with Saturns, but that's a special polymer, not your average plastic.
I was using the curb weight as that is the measure most frequently discussed. We could us the vehicle's GVWR if that makes more sense to you, but the end result is still the same.