6.0l Vs 5.7 Vortec Vs 5.7 Tbi, Propane Conversion ?

oakman · June 6, 2008

What type of milage does the 6.0l get HWY /CITY

5.7l vortec HWY /CITY

5.7l TBI HWY/CITY

This is why I'm interested. I am looking into a propane injected engine;and would like to convert the most fuel effiecient of the 3 engines found in a 3/4 ton truck. I think it would be the 5.7l vortec over the 5.7 Tbi but how much more fuel efficient would this engine be ? Converting to duel fuel the cost is $3000 for 5.7 TBI and $5300 for 5.7 or 6.0l vortec (sequential fuel injection). I think the old TBI milage won't be to far off the 5.7 vortec and the conversion cost is quite less. Any ideas !

98silvz71 · June 6, 2008

What type of milage does the 6.0l get HWY /CITY
5.7l vortec HWY /CITY

5.7l TBI HWY/CITY

This is why I'm interested. I am looking into a propane injected engine;and would like to convert the most fuel effiecient of the 3 engines found in a 3/4 ton truck. I think it would be the 5.7l vortec over the 5.7 Tbi but how much more fuel efficient would this engine be ? Converting to duel fuel the cost is $3000 for 5.7 TBI and $5300 for 5.7 or 6.0l vortec (sequential fuel injection). I think the old TBI milage won't be to far off the 5.7 vortec and the conversion cost is quite less. Any ideas !

Depends on gearing, mileage, care of vehicle. I had a low mileage 96 350 Vortec with 3.73s that got 11 City/15 Hwy. And then my 98 350 Vortec with 3.42s got about 10 City/13.5 Hwy. Most of the guys will tell ya that about 13-14 Avg with a 6.0L on Hwy and I'm sure about 10 City. The TBI I'm not sure about, I had a friend with a 95 350 TBI 2wd that claimed it got 19 Hwy but I'm guessing about 16 Hwy and 11-12 City. All pretty equal just depends on what year you want, configuration, weight carrying, etc.

Hope this helps.

Spurshot · December 20, 2008

I've had a 5.7 (350 ci) 250hp tpi eng 98 2500 extcab 4wd that got 12.5 city/14.7 hwy. I now have a 6.0L 300hp 99 2500 extcab 4wd that I've had since new that gets exactly the same 12.5/14.7

I have some contact with propane in the past. The propane engines I had contact with got less milage than when they were gasoline powered.

I saw this old post on the subject. http://www.eng-tips.com/viewthread.cfm?qid=93871

Personally, I think you'll have to drive a bazillion miles to get the return on investment for the conversion if you ever do get it back. Not to mention the hassle factor.

If you need better economy, maybe a smaller truck is the best way.