MPG difference between a tt and a fiver.

campntn

Well-known member
What is the MPG ranges for my size truck Chevy 2500 HD (or similar model) and an average size fifth wheel? I realize there are lots of variable, size/load/etc, but just a ballpark.

Thanks!
Mark
 

Ray LeTourneau

Senior Member - Past Moderator
What engine do you have? I've had 2 Chevys one a 2001 4X4 8.1 gasser/allison pulling either a 8000# travel trailer, 9500# 5ver or 14,000#5ver would get an average 7.5 towing and 12 not towing. It was running an air injection intake, throttle body spacer and magnaflow single exhaust.
My current is a 3500 dually 4X2 Duramax/allison and is stock. Towing 14,000# 5ver getting 10.5 to 11.5. Not towing 16-18 city/hwy combined. I wouldn't think you would see a major difference between a tt vs. 5th wheel for mpg.
 

nhunter

Well-known member
I don't think it be a major difference but the TT probably gets better mpg due to lower height than a fiver.
 

katkens

Founding Illinios Chapter Leader-retired
nhunter said:
I don't think it be a major difference but the TT probably gets better mpg due to lower height than a fiver.

I've been kinda surprised so far on my mileage difference between my former TT and now the 5th wheel. I have actually gained about 1 to 1 1/2 mpg on the same trips that I have taken with both. I think the enclosed under belly and the air flow is making the difference, guess more time will tell. I just know I'm doing better with the heavier and taller trailer....Ken
 

jpmorgan37

Well-known member
Ken;
I experienced the same thing between my 33 foot Sea Breeze and my 39 foot Grand Canyon. I did about 1 to 2 mpg better with the Grand Canyon. I think it's the design of the front cap.
 

campntn

Well-known member
It is in the design, that's what brought this conversation up in our truck. This 31 foot frame on a North trail tows 75% better and get's about 2 mpg/average better than a 1000 lb and 10 foot shorter Outback we traded. It had a very flat front. This wonderful :p North Trail has a very aerodynamic sloped front. The tow difference is astounding. My friend has the same model Outback we had and when he towed our NT, like me, he could not believe the difference. It's in the design.
Mark
 
I get better mileage with my 37' 13k+ Big Country than I did with my 8K 32' TT. I believe it has a lot to do with wind resistance. Because the 5er sits partly over the rear of the truck both setups ended up being about the same overall pulling length. I believe that the wind treats the truck and 5er more like one unit where the majority of the wind goes over the truck and then over the 5er. I know some wind gets down in the bed but nothing compared to what happens with the truck TT combo. I believe the truck TT combo creates much more frontal resistance than the truck 5er combo.

Another thing I have noticed with my D/A and 5er combo is I get better mileage in tow haul mode traveling at 65mph than I do at 60mph. At 60mph the allison wants to stay in 5th gear to maintain the desired 1700 to 1800 rpms. At 60mph I am in 5th gear running 1800rpms. When I move up to 65 mph the allison shifts to 6th gear and runs 1700 rpm. I never would have believed this if I had not experienced first hand on my Thanksgiving 800mi trip.
 
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