Towing with a 8.1 Gas Vortec

[fixintodoit]

Looking at a 2003 Chey 3500 Dually with a 8.1 Vortec gas engine and 3.73 rear end.( that might be a 4.10 rear end need to check) Pulling a 5th wheel at about 14000# Does anyone know how this would preform and what gas mileage to expect? Book says this truck is rated to tow 15700# with GCWR of 22900# I need to change to a 1 ton truck now towing with a 3/4 ton diesel.Thought I might consider a gasser. Any thoughts??

[RustyJC]

While you're waiting on the GM folks to reply, I went the other way. I was towing our previous 13,500 lb 5th wheel with a Dodge 3500 dually - 8.0L V-10 with 47RE automatic. Although the drivetrain was bulletproof, I spent a lot of time going up 6% grades at 3500-4000 RPM in 2nd gear and watching the fuel gauge drop. Overall mileage pulling this 5th wheel with the V-10 was about 6.5 MPG.

Towing the same 5th wheel with our current Cummins 5.9L HO and NV5600 6-speed, I could pull the same grades in 6th gear and got around 11 MPG. For that difference in mileage, I can pay quite a premium for diesel and still enjoy the improved towing performance of the diesel.

JM2CW - whichever way you go, don't forget to factor the truck's GVWR into your calculations. Manufacturer's trailer tow ratings are really just advertising fluff since (1.) they are based on a stripped truck with only a 150 lb driver and (2.) they ignore GVWRs and GAWRs which are major "gotchas" when towing a heavy 5th wheel.

Rusty

[davtil]

We had a GMC 3/4 HD LB 8.1 A/trans pulling a 13000# Hitch Hiker. With reasonable flat driving with NO wind we got MAX 9 GPM. With other conditions, especially wind, 5 to 7 mpg. In high elevations in Colorado, Idaho, Utah, etc mpg was 3 to 5 as well as on a few occasions it was 1st. gear at 15 MPH. The only difference between a 3/4 and 1 ton is load capacity.

Gasoline engines loose 3% efficiency for every 1000 feet elevation. So at 10000 to 11000 feet the motor is only capable of 66%.

We now have a Chevy 1 ton D/A LB. I'm an easy driver. I usually drive 60 mph. Seldom go much faster. My last trip in Aug, was round trip 4340 miles up to Hardwick, MN. I have 15000 + miles on the truck and was able to get 13 MPG.

I went the gas route first and realized my mistake and went diesel. Pulling the weight you are the only way is Duramax/Allison if you want satisfaction not frustration on your trips.

Hope these words help. Have safe enjoyable trips.

Dave De Valk

[davtil]

I forgot to mention driving with a headwind not only will decrease your MPG but will reduce your driving speed accordingly. On a few occasions driving thru Palm Springs going west with the 5 speed Allison it was 35 MPH in 3rd gear.

[TXiceman]

WHat Rusty said again.

Ken

[Suburbbus]

I have a 2001 Suburban with the 8.1L and quite honestly, I have been dissapointed with the performance. My TT weighs in at 8,000 loaded and it pulls it ok, but the gas mileage is around 8-9 mpg at best. It is also my daily driver and the daily mpg is only about 11-12 maybe at best. When I bought this with the 8.1L, I thought I would have a towing monster. Next TV will be a diesel if at all possible.

Rodney

[xc-mark]

The 8.1 motor pulls ok but its 200 FTLBS of TQ short when you campare it to a deisel...... dont expect much over 7.5 mpg towing heavy with some hills . My duramax gets 10 ~ 13 mpg depending on how fast i tow , and it has no problem on 4~5% grades running 70 mph up hill with my 32' 10000 lb holiday rambler in tow. (it has a little help from Kennedy diesel with his Live EFI 70 hp tow tune).

[xc-mark]

Late 2008 GM will have a duramax in the suburban , with a slightly less power rating then the pickups have.

[fixintodoit]

Thanks to all of you that responed to my posting You have answered my question I am going to stay with a DIESEL, I am going to have to upgrade to a 1-ton that specs out to do the job I need it to. Going to look at a Chey Duramax or a Dodge Cummins. The reason I like this forum is you get answers from people who have been there done that. Thanks again

[Randy the sly old fox]

Take a look at the Dec issue of Popular Mechanics as they reviewed the big three 1T PUs. Not really a fair test because the GMC was SRW while Dodge and Ford were DRW. GMC had the highest rear end ratio at 3.73, Ford had the lowest at a 4.54. I would also recommend that you stick to a diesel.