I have a '94 Suburban 3/4 ton, 2 wheel drive 454 with a 4L80E tranny. I only use it to tow my race car, but at 8 mpg over the mountains, I need to do make a change.

What donor should I be looking for? I would like to keep my 4L80E, and hydroboost brakes. Probably will need a 6.0 for towing, but if a 5.3 is cheap enough I would consider it. Is Displacement on Demand worth trying to use for the gas mileage?

I don't want this to become a long term project, so I'm thinking that finding a donor with the same tranny is a must. What should I be looking for?

Thanks,
Eric

 

Find a crashed duramax.

 

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How much do you suppose I could find one for? I figured it would be out of my price range, but I'd love to have one.

 

What are all of those? 6.0's with 4L80E's ???

 

Not sure what your price range is but if you I imagine you could find one for around $6-7k plus be able to sell a bunch of stuff off it. Most of those are are 5.3l.

 

Damit.. that adds to the confusion... now I gotta look at Duramax's too

 

I only get 11mpg in my Silverado SS (LQ9) and a friend with a 2wd dually got roughly the same. By the time you figure cost per mile (with the diesel) it comes out very close.

 

That seems like kinda low numbers for the max. Gotta factor in possible driving styles and programming stuff. I know a guy with a 3500 single wheel 4x4 with a mileage tune in it and with conservative driving he is getting 23+mpg.

 

He started out by stating the mileage while towing, which is what I quoted 11mpg pulling a enclosed car trailer. On the road driving conservative is 16-17 (Also my SS is AWD 4.10 gears). Add the 25% additional cost of diesel and you are up to 20-21 which is what most people I know with Duramax trucks get.

 

Oh gotcha. Forgot the towing part. And now that I think about that, I have an 05 2500hd 6.0l 4l80e 4x4 and towing a 22' open trailer with my chevelle on it I get bout 10.8. With that being stated not really sure, if towing mileage is the biggest concern, it is worth doing the the swap. You will definitely have more in the swap than you will save in fuel, for a long time. In a scenario where fuel is $5 per gal at 8mpg you are spending $.62 per mile, if you do the swap and are able to get 12mpg it will cost you $.42 and you would have to drive 15000mi to save $3000. In a scenario where fuel is $3.50 per gal you will have to drive even farther to save the same $3000 almost 21500mi. You said that you only tote you racecar around with it so unless you are making some really long hauls with it, it may not be worth the investment. I just threw $3000 out there seeing that's is about what it will have cost me to do the 6.0l swap in my chevelle. There are several variables to factor into this scenario however (cost of eng, ability to sell some stuff, cost of swap parts ie. headers acc etc.). Would be a fun swap to do though.

 

try towing this and i still get around 11mpg but my truck is a 2011

 

I have a 2005 Duramax 4 door 4X4 dually with 4inch Magnaflow ss exhaust Edge with Attitude tuner, Voilant CAI and pull a 36 foot Cedar Creek travel trailer and the best I get is 9 miles per gallon. I do however pull it at 70 miles per hour, I will NOT be one of those ol' farts going 55 in a 70 speed limit.

 

We use an 04 GMC Sierra LQ4/4L80E 2WD, avg about 17mpg hwy unloaded and about 14mpg with a loaded 16' trailer

You can pick up a used truck for under $10k, Id go that route instead of a conversion

 

The Suburban has almost 200,000 miles on it so a new motor is in the near future no matter what. Diesel although it sounds nice is probably too much of a gamble. If it lasts as long as it should it might pay for itself, but the smallest problem would likley cost a lot more than a gas motor to fix. I think I'll look for the latest 6.0 I can get. It sounds like the newer ones with VVT & DOD are getting better mileage. I can't imagine 14mpg while towing. That would be great.
Thanks guys,
Eric

 

Cummins will get the best mileage for towing by far the duramax is a good engine and has a ton of power but it uses more fuel too if I was doing a diesel swap its the only one is put in BTW towing 10k trailer at 70 will get about 5mpg in a 6.0 that's what I have right now and I know

 

Toting a bobcat on a 22' heavy duty trailer doing 70+ still got better than ten in my lq4. I work on cummins on the daily non of our fleet gets better than 6. When I worked a the gmc dealer I saw many work truck duramaxs getting 16+ average.

 

I have a CCLB 03 Cummins Dodge, I've pulled a 10500lb boat with the cruise set at 75, and averaged 14.2. Empty around town I average 19-20, and Highway, at 60mph, no load, I've seen 28. Thats with a MBRP 5in pipe, AFE intake, Modified wastegate, and an Edge Juice tuner. I was a GM tech by trade, and I've never seen a Duramax come near the mileage of my Dodge, but for power wise, the Duramax is a heck of a motor. A gasser will never get the mileage of a Diesel, and cummins swaps are getting popular in that body style burb'