Quote: Now it is true that GM or Dodge do not use the same trans in the gas and the diesel.
....whoops! Just a slight adjustment: GM pairs the 8.1L gasoline Vortec 8100 engine with the same transmission (from 2001 to ~2007) the GM diesels are paired with: Allison 1000
You can still get this engine today (with Allison combo) in the $247,000 T-98 Kombat (strong Russian SUV built for 3rd World country driving, with the often-liked 23 mm autocannon)
OK now...on with lengthening of this Thread.
* This post was
edited 07/13/12 02:36pm by silversand *
If anything, the same tranny behind the less powerful gas engine would last longer than the same tranny behind the more powerful diesel engine.
Also, a tranny in a truck with high axle gearing (3.31, 3.42, 3.55) will not last as long under very heavy use as the same tranny in the same truck with lower gearing (3.73, 4.10, 4.30). The lower gearing multiplies torque and makes for less stress on the tranny and less power demand from the engine.
So, in theory, an F250/350 with the V10 and 4.30 gears, the tranny should last longer than an F250/350 with the diesel and 3.31 gears, assuming both have the same tranny and tire diameter and both trucks are used the same way over their lifetime.
Quote: If anything, the same tranny behind the less powerful gas engine would last longer than the same tranny behind the more powerful diesel engine.
Very good point. The Hummer H1 (not the H2) at one time in the distant past came with the diesel powerplant, and paired with the 4L80E automatic transmission (both the Humvee and civilian H1). Eventually, the H1 (and equivalents) were paired with the Allison & the diesel (much more apropos) by The General, recognizing the error of their ways. The 4L80E is a very strong transmission, however, not paired with a 500~600+ ft/lb torqued engine. We love the 4L80E in back of our Vortec 6000, geared at 4.11; not a hint of trouble over nearly 8 years of use (caveat: meticulously maintained under severe service maintenance regime, and, most importantly not over-taxed).
To me it makes more sense that a trans used behind a 400HP/800torque well put more stress than the 385HP/405 torque engine. Also as SCDR stated the lower rear gear is going to make it eaiser on the trans. When moving big loads the lower gearing makes it easier. The gearing is the same in the trans no matter if behind the gas or diesel.
As to your question I have seen 17MPG. But just for one tank and I was driving slower and really taking it easy on the go pedal. Just wanted to see what it would do and I have the 4.30 rear axle. It was on a country road with a small number of stops but some pulls in it. My average just running around is right in the 12 to 14MPG with mixed in town. This is if I can keep a sensible right foot but it is fun to hear the 6.2 V8 rumble. It reminds me of the old hot rod days. Get on it and hold it and it well start making a throaty noise and rev up. It is an oversquared engine where the bore is bigger than the stroke so therefore it loves to wind up.
As stated I don't drive my truck much (to many other vehicles and retired so don't have to drive much anymore) but after driving it yesterday it put a smile back on my face. Till I got this truck I forgot how nice it was to pull into a fuel pump and not having to look where I walk because some idiot before me fueling with diesel spilled diesel all over when he/she fueled their rig. Also when filling having to wait for the foaming diesel to go down so I can add more fuel to it. I know I have to stop at fuel stations more but my wife needs to go to the little girls room anyway so I might as well fill up also.
silversand,
You are 100% correct on the GM having the allison behind the 8.1. I should have stated with the current new trucks as that was trying to get across.
Butch
2011 F350 KR 4X4 CC LB SRW
2012 Northern Lite 10 2 CDSE
2010 Can-Am 650XT Outlander Max
2012 Harley Tri Glide
Quote: You are 100% correct on the GM having the allison behind the 8.1. I should have stated with the current new trucks as that was trying to get across.
Hi Butch! Good to see you back after an absence. I think you are one of the founding members of the TC Forum, no (you were an active member more than 10 years ago, I think!) ? I post-scripted my clarification with a smiley, because I knew you meant current new trucks
SoCalDesertRider wrote: If anything, the same tranny behind the less powerful gas engine would last longer than the same tranny behind the more powerful diesel engine.
Also, a tranny in a truck with high axle gearing (3.31, 3.42, 3.55) will not last as long under very heavy use as the same tranny in the same truck with lower gearing (3.73, 4.10, 4.30). The lower gearing multiplies torque and makes for less stress on the tranny and less power demand from the engine.
So, in theory, an F250/350 with the V10 and 4.30 gears, the tranny should last longer than an F250/350 with the diesel and 3.31 gears, assuming both have the same tranny and tire diameter and both trucks are used the same way over their lifetime.
I would have thought the opposite. With a weaker engine, wouldn't the tranny shift more often and wear out sooner?
SoCalDesertRider wrote: If anything, the same tranny behind the less powerful gas engine would last longer than the same tranny behind the more powerful diesel engine.
Also, a tranny in a truck with high axle gearing (3.31, 3.42, 3.55) will not last as long under very heavy use as the same tranny in the same truck with lower gearing (3.73, 4.10, 4.30). The lower gearing multiplies torque and makes for less stress on the tranny and less power demand from the engine.
So, in theory, an F250/350 with the V10 and 4.30 gears, the tranny should last longer than an F250/350 with the diesel and 3.31 gears, assuming both have the same tranny and tire diameter and both trucks are used the same way over their lifetime.
I would have thought the opposite. With a weaker engine, wouldn't the tranny shift more often and wear out sooner?
Shifts do put wear on it but with more torque applied there's more stress on everything from clutches to bearings. Gas engines don't necessarily have to shift more often if you leave them shifted down in the up & down hilly areas. Your mileage will suffer though.
SoCalDesertRider wrote: If anything, the same tranny behind the less powerful gas engine would last longer than the same tranny behind the more powerful diesel engine.
Also, a tranny in a truck with high axle gearing (3.31, 3.42, 3.55) will not last as long under very heavy use as the same tranny in the same truck with lower gearing (3.73, 4.10, 4.30). The lower gearing multiplies torque and makes for less stress on the tranny and less power demand from the engine.
So, in theory, an F250/350 with the V10 and 4.30 gears, the tranny should last longer than an F250/350 with the diesel and 3.31 gears, assuming both have the same tranny and tire diameter and both trucks are used the same way over their lifetime.
I would have thought the opposite. With a weaker engine, wouldn't the tranny shift more often and wear out sooner?
I don't let mine shift up and down but yes if a trans is constantly hunting for the proper gear is hard on them. But applying almost twice the amount of torque to the torq converter and at lower RPMs if the converter hasn't got a chance to lock up well cause a lot of heat.
When approaching a hill if I feel I well need to shift down I just use the manual mode with the tow/haul engaged and shift down manually. I get in a gear it well pull the hill in and and where I can back out of the go pedal and just let the truck pull the hill. I don't have to be the first one to the top. That has never bothered me. If it takes me 1 to 5 minutes longer to reach the top of the hill no big deal as in over the course of a days worth of driving it isn't going amoount to a hill of beans.
But like I stated earlier if you want a diesel than I would suggest you buy it because if you buy a gas you most likely always look for things that bug you about the gas and well not be happy. I have had the the diesel trucks and know what I'm missing but I'm very happy with my gas. If my needs change then I'll end up back to a diesel but at this time I don't foresee that.
But like I stated earlier if you want a diesel than I suggest you get a diesel. If you bought a gasser after really wanting to go diesel than you well not be happy and well find faults with the gas one. I have had diesels and if my needs changed that I needed one I would sell the gas and buy a diesel but I don't foresee that happening as I'm very happy with my truck.
Thanks for the feedback. I did not understand the torque piece. For me, it will mostly be an economic decision. Right now that is looking like diesel if the truck also serves as a DD. I could easily put on 10,000 mies loaded, 20,000 total....
diver110 wrote: Thanks for the feedback. I did not understand the torque piece. For me, it will mostly be an economic decision. Right now that is looking like diesel if the truck also serves as a DD. I could easily put on 10,000 mies loaded, 20,000 total....
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