Diesel vs Gas

[B&J]

I am thinking of buyiing a new 2008 Super Duty F-250. Instead of the new 6.4L Power Stroke Diesel, I am considering the V-10 gasser. I pull a 28' CCD International (7300 GVWR), so the V-10 should be adequate. For improved mileage, I'm thinking I need the higher gearing/lower ratio rear-end (4.10). I also plan on having a Banks Power Pack installed to help with the performacne. My question is, would this be a good alternative to the diesel? Am I analyzing this correctly? The cost of a gas engine (even with the Banks upgrade) would be less than the cost for the diesel engine. Also, the fuel cost per gallon between regular gas and diesel fuel is significant. Would like feedback from anyone that has some thoughts and advice. Since we live on the west coast, we will be traveling up and down steep grades.

[bill benton]

With the v10 you can probably stay with a rear rend somewhere around 380. The turbo would be a nice add on, but may not be necessary

[davidz71]

Don't forget to consider the better mileage you receive with the diesel. If you are talking about steep grades then you are probably better off with the diesel. Since a steep grade also has the other side going down, an exhaust brake might also come in handy with the diesel. I have an '01 2500hd with 8.1 and have been happy with it but if I was traversing steep grades, I would rather do it with the diesel.

[Phil Gobie]

I have and have had both. I happen to be a GM fan. Regardless of brand I think it is more personal preference than cost. Long term, very long term the diesel should come out more cost effective theoretically. But realistically it may not. I still prefer the diesel for the way it drives (low end torque). The GM offers the Alison transmission with the large block or the diesel. For me if nothing else this transmission is superior to any others out there. It is what is used on commercial busses day in and day out. I also like the diesel for the simplicity of the engine. There are no spark plugs, or ignition system! Virtually all semis and commercial trucking use diesel. I am using our family truck a 1500 gas Avalanche for a TV for now but I will likely change to a GM diesel with an Alison trans on a 2500. My work truck is a 3500/diesel/Alision I love the way it drives and I have changed the trans. fluid to one that is good for 70,000 miles. If you tow in the mountains with an Alison I don't think you would consider any thing else.

[Silvertwinkie]

I agree with Phil...for the most part, it's a personal pref. I also agree that the Alllision trans is really the best one out there...period....and you won't find that in Ford or Dodge.

Diesel does get better MPG, but for the past year, it's been more expensive than gas. Add to the fact there is a premium for the diesel engine option and overall higher costs on oil changes. But the it's not uncommon for a diesel to last 500k miles.

Most folks with gassers get around 10mpg. Some less, some a bit more, but not too much more unless they are towing at 45 or 50mph. Faster=less mpg and closer to or below the magical 10mpg.

Diesel OTOH, gets typically between 12 and 15mpg towing (of course depending on load, terrain, etc).

If going gasser I'd stick with as close to 4.10s. Diesel, 3.73s are fine. The rear gears are basically torque multipliers...which diesel clearly doesn't need.

If you had a 34' or a 34' slide out or a 30' slide, I'd lean toward a diesel, but in your case, either could really do the job. What I'm very happy to see is that you are being proactive and thinking about this ahead of time....to me that's half the process right there!

[flightlevel5]

B&J,

As the others have said it is a matter of personal preference which brand you purchase but regardless diesel is hard to beat.

I owned Ford F150s and F250s for a long time but Ford service was really beginning to suffer so I decided to give GM a try. I purchased a Silverado 3500 extended cab 8' bed single rear wheel diesel in 2005 to tow my 30' Classic SO.

I get 20-22 mpg when not towing and 13-15mpg towing the Classic. The Allison transmission is the best made and if you purchase a 2007 both the Duramax engine and the Allison transmission have been improved. The Allison is now 6 speed overdrive with a tow selection which is excellent. Going down hill or decelerating on an exit ramp requires virtually no braking in the tow mode. While I almost always use a friction sway bar when towing I have towed without it and have never experienced any sway. I admit the 3500 is definitely more truck than required for towing any airstream but the additional load capacity, and braking capacity come at a small price.

Both Ford and Chevy have reduced the diesel engine noise to minimal levels as well as emissions.

Larry

Remember, "if the women don't find you hansome, they should find you handy" - Red Green -

[Goin camping]

I have had both and for me the diesel is the tops. I love goin up steep grades with the ability to hit the throttle and pick up speed. While getting 15 mpg towing.

Good luck in whatever you choose.

[jdalrymple]

Stay with diesel. I have, and prefer, the GM product. The driveability is better IMHO. I don't follow your theory of a lower gear ratio yielding better mileage. The lower the final gear, the higher the RPM must be to make cruise speed. Meaning more fuel expended. As stated I have the Duramax/Allison and have added a cold air intake system, 5" exhaust system, and the Edge Juice "chip". I get 15.5 mpg towing and 20 mpg empty. The cruise set at 65 mph will hold on anything but mountain passes with no downshifts.

[CanoeStream]

Originally Posted by B&J

For improved mileage, I'm thinking I need the higher gearing/lower ratio rear-end (4.10).

You've got this upside down. That's 4.1 rotations of the drive shaft for 1 rotation of the drive axle -- thus it is lower gearing and somewhat less mileage than a 3.73. It is for this reason that economy cars have "differential" ratios in the low 3's (mixing metaphors for the FWD world) -- but the result is that the lower ratios do a much poorer job of transferring torque to the drive wheels.

Another disadvantage of gassers is the tranny & controllers that cause it to shift down out of overdrive on the next small hill. Repeated downshifting adds heat & wear to transmission components. My ex-Nissan Titan was a 5 spd auto -- it shifted all the way down to 3rd when faced with the next rolling hill! Owners manuals do a good job of explaining that you shouldn't tow in overdrive if dealing with a lot of gear searching -- thus further sacrificing any mileage performance. It is difficult to justify exceeding 60mph with OD off in my experience. Long descents or the flattest of roads are the only guaranteed times that OD works well while towing -- but like always, results may vary with tow vehicle...

The 8L Chev & V-10 Ford have the power but are real gas hogs! My 5.6L Titan struggled to get 10mpg towing in the midwest. I suspect a V-10 would get .... ulp! Diesel engine payback takes 150-200K miles if you don't consider the higher resale. But the lack of towing problems is worth it to me.

An observation from my first season towing with my '06 GMC Duramax-Allison is the value of the computer control of that transmission. If I approach a descending grade with the power on the overdrive will let me coast and pick up speed. If I crest the hill with the power off the transmission will manage my downhill speed so that it rarely increases -- including while towing! My owners manual says to watch for gear searching (almost nonexistent for my Allison) and the diesel trannys usually can stay in overdrive.

[Silvertwinkie]

I'm not sure how accurate that might be Bob. Any truck equipped with a tow/haul doesn't hunt that much either. Some granted, but not to the level of non-tow/haul equipped vehicles. Tow/haul, even on the non-Allison 4L80e for example limits the downshifts, line pressures, etc. My SS that that didn't have tow haul towed in overdrive all of it's towing life because I set the torque converted to lock sooner than later. An unlocked torque converter is the number one cause of heat. I won't deny that the Allision/Duramax combo is the best on the planet IMHO, but don't rule out the gassers that are properly equipped, they can be equally effective and not have the issues described.

[CanoeStream]

And for that reason I said results may vary. Tow/haul the way I understand it raises the shift points so that each gear is carried to a somewhat higher speed -- don't know that it'd really affect transmission function at cruising speed.

The answer was simple for me. The 'Big Tow' package () wasn't enough to keep me from unloading my 2 year old Titan at first opportunity last January. We all have taken our steps in progression to good tow vehicles. And I shouldn't forget that there are some good gas powered TVs out there.

[JimGolden]

I had a Ford Excursion with the V10. I got 9mpg average towing with it. I now have a Dodge Ram with the diesel. I get about 13mpg towing.

It did tick me off after I bought a truck that gets 30% better milage than a gasser and they went and jacked the price of diesel to 10% above regular.

Other than towing, I like the gas engines better. They "rap up" quicker, are less messy (you always have to use your grime mit when fueling a weasle...lest you get filth all over your hand...somewhere somebody hogged up the gas pump handle and diesel doesn't flash off like gasoline, so it causes crud..."

But all that being said, I really like my Dodge. It's the newer style, and is very quiet. My dad's '99 will rattle your teeth, but my '04 is hardly noticable at freeway speed.

I'm wondering if I shouldn't have gotten a shorter trailer and just stuck with the hemi in a half ton. Maybe like gotten a '60's 26 footer or something. My buddy has a hemi in his half ton truck and gets 22mpg with the cylinder deact. Pretty incredible. I average more like 18mpg with my Cummins. Although, I've gotten 21mpg with it on flat ground. I live in WV though, and flat ground is hard to come by here

Take your pick. OPEC will love you either way

[moosetags]

I liked the diesel, but I did the math, and have just about changed my mind.
Diesel is now costing between 25 and 30 cents more per gallon that diesel. This dfference efectively negates the MPG advantage for diesel. I did some research on servicing of diesels, and found that even though the service interval is longer, the cost is considerably higher. When coupled with the fact that the Duramax option on GMs is $6,500.00, it makes me rethink my planned diesel purchase.

I have been running an '05 GM 2500 with the 6.0 gas engine. I have been very satisfied with its performance pulling an '05 25' Safari. It pulls strong even up a steep grade, abiet with more downshifting than I would like. I am a big fan of automotive overkill, and therefore, want "more power", just because. SuEllyn does not fully understand my reasoning in this area (I can't understand why), but supports me anyway.

In my never-ending quest for more TV, I am now considering a Chevy or GMC 3500 (non-dually) with the 8.1 liter gasoline engine which is now available with the Allison six speed transmission. I think that this combination will do the job and then some. I am also a little afraid of this new diesel technology.

[silverback]

I'll never go back to gas. We've switched all our vehicles to diesel. BTW - Our towing average MPG is 13.9 pulling the 28' Safari SE. The DMAX (LB7) also loves to have B99 bio-diesel blended in.
-K & L