Diesel vs. Gasoline

dave40

http://uscom.com/~hoot/cars/news5.htm

Rich

Pocono,
I have the '99 F-250 SD, 7.3L and 3.73 rear end. My mileage on a recent trip (LA to Reno) was 19. In typical LA traffic it ranges 16.25 to 17.5. The truck weighs 7060 with a full tank, cross bed tool box an me (230).

speedster121,
My truck is limited to about 91 MPH by the Ford computer. At 70 MPH the engine is turning about 2050 RPM. There's still another 1500 or so to go before the red line.

Rich

binns

I haven't seen this question asked, might have missed it but here goes.
Considering all else as equal (rear end ratio, tranny, approximately the same size pickup, etc) what would my speed be when topping a long pass, such as the Grapevine or Dunsmere hill, while pulling my 7K lb 5th wheel with a; the new Ford V10, the PS, the Dodge V-10 and the Cummings?
I have heard all the drill on torque v horsepower and all but the bottom line for me is, how much faster could I top the hill with one of the above engines as compared to my present F250 Super cab, 5spd, 460?

markbuck

First place to the top of the hill:
Dodge V10
Ford PS
Your 460
Cummings (close on the tail of your 460)
new Ford V10

Burn the least fuel during same run
Cummings
Ford PS
Ford V10
Your 460
Dodge V10


Go ahead, rip me!

markbuck

All things being equal, more air in = more fuel burned = more power
Diesels are penalized by not being able to run gas motors 14.7:1 air/fuel ratio, more like 20 to 25 to one, they smoke really bad below that.

Dodge 8.0L
Ford PS 7.3L + turbo boost - diesel penalty
Ford 7.5L (460)
Cummings 5.9L + turbo boost - penalty
Ford 6.8L (v-10)

mpazos

Just a slight tear. Cummings = Cummins...
I think the diesels will out perform the gas engines. Diesels run leaner but produce more power(btu's) per gallon. This should start it going!!

lvstang

Binns, what year 460? I used to have an '85 with the 4bbl. I put the Elderbrock system on it;cam, manifold, Doug Thorley headers, dual flowmasters. I swear I could pull Grapevine and or Baker grade going either way with an 11' camper and 26' Nordic at 65 m.p.h. Empty the truck was awesome. Sold it to my brother-in-law who swore he'd keep it in the family. He sold it without me knowing. I don't believe any of the stock $30,000 trucks could do that. Anxiously waiting to get ripped.

Brutus

On an extended steep grade with a big fifth wheel, my money would be on the diesels, with the PSD besting the Cummins. Running empty or with a light load might be different. Then again, a 7,000 pound fifth wheel isn't all that heavy.

Markbuck's fuel usage rankings is what I would guess. I just took a 225 mile trip running empty this morning and averaged 11.7 mpg with the mph close to 70 most of the time. Remember that I have the 4.30 axle ratio and dually 4x4 with my Ford V-10.

gbrudevold

Should I buy a cummins or powerstroke to pull
my 28 ft fifth wheel.

tom60

I would buy the powerstroke especially if you are traveling any hilly terain. The PSD will out pull the Cummins on a hill.

markbuck

IMHO,
better power with PSD.
better economy with cummins.
better truck with ford.
longer engine life and better rebuild's with cummins.
Crew cab with ford.
Dealer service - only you know

your call....

markbuck

Had a '88 class C motorhome with 460 plus did Ford's power up kit in '92 (new computer program)

Had a '89 7.3 non turbo in a F350 2wd. Same rear end in both 3.55.

460 would out pull the 7.3 any day of the week.
7.3 would beat the 460 on fuel even downhill off a cliff.

wwhite2

GM's new duramax diesel 300 HP 520 ft lbs
Dodge's new Cummins ETH 245 HP 505 ft lbs
Are going to add a new twist to this topic!!!! never mind GM's adding an Allison 1000 auto and 6spd to match the Cummins 6 spd. Cant wait for these drivetrains to be available

Brutus

Isuzu, Navistar, and Cummins all make diesel engines with alot more torque and horsepower than the engines they put in pickup trucks. It's not a matter of which manufacturer can produce the biggest engine. It's a matter of combining it with a tranny and drive train that can handle the power and fit into a pickup, while still providing a fair amount of comfort for long highway trips. If we were just looking for pure torque, we could hook up our RVs to a front end loader. All of the Big Three are in the 500 lb-ft of torque range. Soon, they will be in the 600. Who will get there first? Who knows?

nut4scuba

Hey anyone heard of any aftermarket computer chips for the 7.3 L diesels that increase HP and/or torque.. Gotta new 2000 Diesel on order

wildmanbaker

I don't know who been driving what powerstrokes or what cummins, but in hilly country the cummins will and do out pull the PS. The PS may be faster on the flat, but when the computer limits the top speed, you will never see the difference. If economy is the driving factor, get the Dodge, better mileage, less oil cap., and less for the diesel option. Cold weather performance, the cummins beats hands down. Get the one that you can live with for a long time.

wildman

leathal02

actually i dont think that GM has released any info on the specs of the DURAMAX, they wont come out until it is officially release

wwhite2

Reliable sources state 300 hp and 520 ft lbs for the Duramax and a number of advances that make for better driveability. Guess will we just have to wait and see

mpazos

Brutus hit the nail on the head. It's the complete package. That is why I like my Chev 3/4 ton w/6.5L turbo diesel. It is not as powerful as the other diesels currently available, but it near perfect in combination with the 4L80E auto, NVG 241 transfer case, Corporate 14 bolt(10.5" ring gear) differential. Info on the Duramax:
http://www.62-65-dieselpage.com/news5.htm

time4family

Want a Dodge Get it now with a rebate on some models.

Want a Ford get in line.

I wanted a Dodge but I bought a Ford. The vibration on the throttle pedal was really annoying and the IDIOTS at Chrysler discontinued the crew cab.

My Powerstroke pulles my 10,500 pound boat and gets 14.2 mpg while doing it.

My buddie has a 96 Cummins with 291,000 miles on it and has only had to replace 2 trannys. He loves it but it is not for me and it won't suit my needs.

Diesel is a labor of love. You like them or you don't. Remember it must "work for you"

abrams

i've read through this whole topic and learned a lot. but i have one question that was not addressed. i shouldn't want to speed... BUT...
what top speeds can be expected from the following combos;
psd+f350sddrw
psd+f250sd
v10+f350sddrw
v10+f250sd
cummins+3500
cummins+2500
v10+3500
v10+2500
all 2wd and assuming whichever gear ratio is best for flat speed. by the way, which ratio would that be?

abrams

markbuck

Don't know about the dodges.

Dodge V10 makes the most power.

The things don't handle that well above 100 anyway.

Buy a LS1 Camaro or a Suzuki Hayasuba if you wanna go fast. Camaro good to round 160, Suzuki good to close to 200. Both alot cheaper than a truck.

wildmanbaker

Late model Fords are limited to about 90 +/- 2-3 mph. Dodges are limited to 100 mph, by the computer. Sorry, but the 95 Club Cab we had handled very well at 100, and seemed to happy at that speed, but there are others on the road, and these speeds could be very risky. The raised 4X4s may not be as stable (higher CG., more air under the truck, etc.) as the 2Xs at higher speeds.

Wildman

markbuck

My silverado is limited to 98mph. My ford buddy claims his is limited to 100. He musta been stretching the truth....

abrams

thanks for the info so far but...
i also asked about the top speeds of the diesels and about which axel ratio is best for quickness.

abrams

Brutus

Since your engine will always be pulling more rpms at any speed with the lower axle ratios (higher number, the taller axle ratios should let you go faster before you redline. So, in the Superduty, the 3.73 should let you go faster than the 4.10 4.30.

Of course, that is all out the window if the vehicle is governed. I've heard the Superduty with the PSD is governed to have a top speed in the 90s. I don't know about the V-10. I've not had mine above mid 80s. I'm sure you can do 90 with either axle ratio, but you will be pulling more rpms at the same speed with the lower one. I've got the 4.30 with my V-10, and I'm generating about 2,400 rpms at 70mph.

abrams

can the speed governing business be over-ridden?

quadrunner500

Skip the Hayabusa...dead on arrival. Wait for the Zx-12 Ninja. Me? I think I want a KTM400E/XC.

markbuck

Better get in line, not too many coming to US this year. I bought a 2000 KTM380exc. Separated left shoulder next day. Missed softball tourneys, a flag football tourney today, but will be able to hunt next week. Will let yawl know how the 1/2 ton silverado hauls elk....

Still don't know why top speed on a diesel is important. Kinda like wanting to know how many bushels of manure a corvette can fit in the trunk.

nut4scuba

I have two friends with PSD 1999 F350 CRew cab drw trucks, less than 12,000 miles. One has had four torque converters replaced and the other has had one replaced.
Both have towed only a Lance camper and once in a while a jeep too. Anyone got any info regarding these torque converters?? as I have a V10 on order now and was going to switch to diesel, but Now I don't know. helppppp!

cdean

I've heard the new powerstokes have a rather complicated "double" flywheel assembly. this is used for engine vibration damping, but they've had a few minor probs with it. Not sure, but torque converter problems could be related to it.

rblundg

I have the 97 power stoke in f250 ext auto. 4:10 with 25,000 miles. average about 13 to 16 mpg in town & 19 to 22 on the open road empty. with a big load ( 8,000-9000 lbs) I get 11 to 13.5 mpg. No problems at all except vibration in front end when new. Tsb fixed that. It is all stock except for a K&N Filter. Friends I know who have the cummins love them but I can walk away from the autos. & on long pulls can out pull the stick. Even the dodge people I know admit the PS will out pull the cummins but the do get better mileage than the PS.
I have had my PS up past 95 several times (speedo limit) & is still pulling I suspect it goes to atleast 100. but that is really true comparing a corvette with how many tons of horse manure it will carry. I didnt get it to go fast just to be able to go the freeway speeds with a big load which it does very good.

lvstang

It sounds like your Gross combined vehicle weight rating (gcvwr) is 16000 lbs. That is the total amount your rig can weigh including payload AND trailer. I believe your figures to be correct. gcvwr minus loaded rig= what's left to tow. I also believe a simple axle ratio change would put you into the safe range. I know not so simple with 4x4. But I believe you did answer your own question. 8700 is it.

wildmanbaker

I assume you have weighed the truck. This seems heavy for a 3/4 ton. Ours weighs 6760 with a canopy, tools, firewood, fuel, and other camping equipment. The rearend ratio is a little high for the weight of the trailer, but it will pull it. You will probably notice any head-wind, or steep/long grades more than if you has a 4:10 ratio.

Wildman

frike

just came home so I hoped to get information on towing. thank you everyone for your help.

frike

brutus-how fast or how slow is dogging-it.

quadrunner500

That's a close call. If you trade in 4 yrs, you are not going to see your money back. I think the safer bet is getting the Diesel and holding on to it longer. Resale on a heavy duty like that, with dump bed would have more appeal too. If you can stand the noise, you will prefer the diesel, but the V10 is a great engine too.

lvstang

"If you can stand the noise" and the sluggishness and the smell and .... If you're going to go 4 years and 100,000 miles go V-10. More than 100k consider diesel. V-10 is so much smoother and quieter and easier to live with on a day to day basis. Unless you're working the diesel hard everyday I just don't get it for a daily driver. Almost everyone agrees on these posts it will take aprox. 100k to get your money back on the diesel so that is why I'm using that as a cut off. I know I'm going to get bashed but that's just my opinion.

quadrunner500

With you on all points but sluggishness. That Navistar does not seem sluggish from what I've seen.

quadrunner500

It may be a daily driver of necessity, but a chassis cab dually with dump bed pulling a trailer all the time isn't what I would call a personal use vehicle vehicle either, where car like qualities reign most important. That's why I feel the diesel choice is okay, even if it doesn't quite break even on fuel savings until 100K miles.

quadrunner500

As for the part about "for a daily driver, I don't get it."

Well, some of this is just the ego stroking, image conscious factors at play with some buyers. I mean, personally, I'd be embarrassed if every time I pulled along side of someone, they rolled their windows up and held their noses. I had to shout at the drive-in window to be heard over that clattering diesel behind me. But some people like showing off. Some hither, others yon.

wildmanbaker

These are all good points. The Ford V10 is not considered a powerhouse, but will be adequite for the job, if the load is not real heavy. This statement comes from talking to people who have the V10 in motorhomes. If you get the diesel, you will more than likely get more than the difference back at trade-in time. You are probably looking at 7 MPG difference between the 2. Just remember, the PSD holds 12 quarts of oil, and needs to be changed every 3,000 miles.

Wildman

lvstang

Good points all. Quad, your comment on ego was exactly what I was referring to. Sluggish comment was in regards to seat of the pants off the line. the V-10 just revs so much quicker and feels stronger out of the hole. I did test drive them back -to-back and that's what I'm basing my opinion on.
Wildman, I consider the V-10 a powerhouse just for the fact I'm ordering one. Just kidding. I do think it's a powerhouse just for the fact you stated. The darn engine is almost never in anything under 7000 pounds, motorhomes,Super Dutys etc. I just think it's too hard to live with a diesel for four years to see a return.

brett039

dharlan,

It's true that to get your money back for the cost of the diesel in fuel saving would take appox. 100K miles. But it sounds like you'll be towing a trailer most of the time. I would think the diesel would drop fewer mpg's under a heavy load (trailer and equipment in the bed) than the V10, and that would mean even more of a savings in fuel! Plus, with the V10 towing a heavy load, you'll spend more time at the pump.

One thing to keep in mind if you go to the diesel. If you make a lot of short runs (between work sights) where the engine doesn't have time to completely warm up, then you might be better off with the V10. This kind of driving is hard on a diesel.

Has for the smell of the fumes at a stop light... Funny, I don't seem to smell a thing when in my truck...

Brett

quadrunner500

Funny but that's about what my buddy said about his '97 PSD..."I don't hear a thing..."

But comparing the sound, either one, 24V or PSD sounds loud at idle. But when it takes off, the 24V takes on a quieter, mellow tone, where the PSD just gets raucous, or so it seems to me.

nut4scuba

what is considered a short trip for the PSD not to get fully warmed up. A couple of miles?? 5 miles?

jack38

I have a 99 Dodge Ram 2500 diesel auto qc 4x4, towed my 8000 lb 5th wheel last weekend for the first time. At 60 MPH with OD off, the motor is cranking at 2500 RPM with very little left on the pedal for passing. Will I do transmission damage if running on flat land in overdrive? Lot less engine noise and available acceleration at 1750 RPM vs. 2500 RPM when towing. Are there any experienced 5th wheelers who tow with dodge ram cummins to answer this question once and for all? THANK YOU.

time4family

Something doesn't add up here. I am pulling a 10500# boat with my 2000 PSD Ford. I know it is a Ford but I feel the Dodge and the Ford (dispite their differences) are both great motors. I run about 22-2300 around 60 and I have lots of power left. I have punched it just to see. (my old 86 Suburban was a gutless wonder so I may be biased) It is nothing to gain 15-20 mph in a short time. I get mid 13 MPG towing and mid 16's non towing.
as I have said before if you like a diesel buy it you will like it more, if not stick with gas (Ford increased the HP on the V10 for 2000) Buy what you like and drive it. I don't mind the guy who has to roll up his window when he is next to my exhaust. (why did he buy a car that is so low to the ground?)
T4F

rrichf

lvstang,
I haven't been into stoplight racing in 30 years so the acceleration factor is unimportant. I've had 3 daily drivers that were and are diesel. Once you own one and drive it you'll never go back to gasoline. The torque is awesome and makes the LA commute easy. (Not fun, but easy.)

Originally I fell into the mileage thing and bought the first diesel. (6.9L in an F-250) At the same time a co-worker bought the 460 gasoline. After comparing mileage for the first few tank fulls, we both lost interest. Yes, the diesel does better, but so what. If you want to do some stop light racing you buy gasoline power.

It seems that the diesel vs. gasoline debate has as much emotion as the Chevy/Dodge/Ford debate. If you don't like diesel, I hope that you enjoy driving your gasoline vehicle as much as I enjoy my diesel.

Rich

lvstang

Rich, I agree. Drive 'em both and may the better motor win. I still think, however, that the 100,000 mile mark is the aprox. break even point for the initial cost of the diesel. After that the diesel will pay dividends both in economy and longevity.
Happy test drive