Chevrolet 8.1 Vortec advice

C29404 · 12-22-2020, 09:33 AM

I have a 2007 3/4 ton pick-up with the 8.1, its 2wd with 4.10 rear and the 6 speed Allison trans, does any one have any advice on improving towing mileage? I tow a 26 ft Gold Rush with a 2700 lb car and race day stuff, it currently has a Voliant cold air and a Black Bear tune through EFI Live. Any additional input is appreciated.

Mike Pearson · 12-23-2020, 09:29 AM

What does it get for mileage now towing?

C29404 · 12-23-2020, 05:07 PM

Towing 6 after tune 7.3
Driving 9 after tune 12-13
Am I expecting to much?

Mike Pearson · 12-29-2020, 02:56 PM

That's some pretty poor fuel mileage. My Freightliner toterhome gets better towing mileage than that truck.

I have had 4 different dually pick up's all had diesel engines and all got about the same fuel mileage. 9-10 towing and 15-17 around town. My toter gets about 8-8.5 towing and 10 empty. Same trailer on all the trucks loaded 40 ft gooseneck 14K lbs.
That being said gas is cheaper per gallon than diesel fuel so that offsets the cost a bit. How much long distance towing do you do and what speed do you run when towing?

Rich Biebel · 12-31-2020, 10:07 AM

I had a '96 GMC 2500 HD 4x4 that I used for towing for years.

7.4 with auto overdrive and a 3.73 rear

It got about 10 MPG or less towing a 26' trailer with a Lance Camper loaded in the bed. I can't recall exact figures but I know that's close. I changed a few things but it made very little difference mileage or power wise.

My buddy had an 8.1 pickup and mileage was poor and lower than my 7.4 pickup for sure...

My '96 Pickup never got better than 15mpg on the highway and not towing anything....and that was driving 55-60 ....

I have a Class C E450 Ford motorhome with a V10 it gets about 7MPG towing the same trailer...

My Duramax pickup gets 12-13 back and forth to work.....10-11 towing with the camper and trailer out back when I used that truck...

The 8.1 has always had a reputation for poor fuel mileage similar to a Ford 460.....

C29404 · 12-31-2020, 03:01 PM

Most trips are less than 250 miles, mainly in the Carolinas. Mixture of two lane roads at 50 to 55 miles per hour and highway/interstate 60 to 70 pending on traffic. At speeds of 50 to 65 it shifts a good bit but at 65 and quicker it smooths out. Before the tune any kind of grade change it would drop back to 4th, its not as bad now will drop to 5th and pull on.

Tom Meyer · 01-03-2021, 06:11 PM

We tow with a 02 Suburban 3/4 ton 4l85E trans, 4.1 gears 265/65 /16 tires. We got about 7mpg. This last year got rid of the cats put in a balance tube up front and a flowmaster cat back system on. From there we went on a wheel dyno for the tuneup, picked up 50 lb of toque and 40 hp at 2300 rpm. It has great power towing but now gets 7mpg. We will be doing a intake mod [google 8.1 mod] have the intake done just need to install it. I just do not think these almost 500 ci motors are made to get mileage, but they pull great and are cheaper to maintain than a diesel. Tom

Glenn Briglio · 01-05-2021, 01:14 PM

Quote:

Originally Posted by C29404

I have a 2007 3/4 ton pick-up with the 8.1, its 2wd with 4.10 rear and the 6 speed Allison trans, does any one have any advice on improving towing mileage? I tow a 26 ft Gold Rush with a 2700 lb car and race day stuff, it currently has a Voliant cold air and a Black Bear tune through EFI Live. Any additional input is appreciated.

What engine rpm is it running at what mph?

FED 387 · 01-05-2021, 06:33 PM

supposedly the OEM air induction system(filter ,tubes ,air cleaner box) is more than adequate to handle the 8.1 it's the opening for the throttle body that is the restriction---the cold air actually makes the engine WANT more fuel so with an increase in fuel consumption AND power while you get a decrease in MPG. Second use lots of synthetic fluids in the rear , trans if you can and engine oil.---third put a tonneau cover or a cap on the bed to help smooth out the air flow over that open bend---maybe put a chin spoiler under the front bumper to help smooth that area out-----then change to a 3:73 rear from that 4:10 to cut down on RPM 's at cruising speed --and finally maybe either a nose cone on the front of the trailer and or a spoiler on the top of that cap to move the air up and over that flat front of the trailer---FED 387

Tom Meyer · 01-05-2021, 11:37 PM

Cruse rpm 2300 to 2500 65 to70 mph peek torque was at 2500. Taller rear tires can help with gearing. We have over 200 k on the clock still going strong. The hole in to floor of the intake floor is the restriction, Tom

12-22-2020, 09:33 AM	#1
C29404 Junior Member Join Date: Dec 2016 Posts: 20 Likes: 0 Liked 0 Times in 0 Posts	Chevrolet 8.1 Vortec advice I have a 2007 3/4 ton pick-up with the 8.1, its 2wd with 4.10 rear and the 6 speed Allison trans, does any one have any advice on improving towing mileage? I tow a 26 ft Gold Rush with a 2700 lb car and race day stuff, it currently has a Voliant cold air and a Black Bear tune through EFI Live. Any additional input is appreciated.

12-23-2020, 09:29 AM	#2
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,442 Likes: 613 Liked 1,915 Times in 574 Posts	Re: Chevrolet 8.1 Vortec advice What does it get for mileage now towing? __________________ Mike Pearson 2485 SS

12-23-2020, 05:07 PM	#3
C29404 Junior Member Join Date: Dec 2016 Posts: 20 Likes: 0 Liked 0 Times in 0 Posts	Re: Chevrolet 8.1 Vortec advice Towing 6 after tune 7.3 Driving 9 after tune 12-13 Am I expecting to much?

12-29-2020, 02:56 PM	#4
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,442 Likes: 613 Liked 1,915 Times in 574 Posts	Re: Chevrolet 8.1 Vortec advice That's some pretty poor fuel mileage. My Freightliner toterhome gets better towing mileage than that truck. I have had 4 different dually pick up's all had diesel engines and all got about the same fuel mileage. 9-10 towing and 15-17 around town. My toter gets about 8-8.5 towing and 10 empty. Same trailer on all the trucks loaded 40 ft gooseneck 14K lbs. That being said gas is cheaper per gallon than diesel fuel so that offsets the cost a bit. How much long distance towing do you do and what speed do you run when towing? __________________ Mike Pearson 2485 SS

12-31-2020, 10:07 AM	#5
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Chevrolet 8.1 Vortec advice I had a '96 GMC 2500 HD 4x4 that I used for towing for years. 7.4 with auto overdrive and a 3.73 rear It got about 10 MPG or less towing a 26' trailer with a Lance Camper loaded in the bed. I can't recall exact figures but I know that's close. I changed a few things but it made very little difference mileage or power wise. My buddy had an 8.1 pickup and mileage was poor and lower than my 7.4 pickup for sure... My '96 Pickup never got better than 15mpg on the highway and not towing anything....and that was driving 55-60 .... I have a Class C E450 Ford motorhome with a V10 it gets about 7MPG towing the same trailer... My Duramax pickup gets 12-13 back and forth to work.....10-11 towing with the camper and trailer out back when I used that truck... The 8.1 has always had a reputation for poor fuel mileage similar to a Ford 460..... __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 12-31-2020 at 10:10 AM.

12-31-2020, 03:01 PM	#6
C29404 Junior Member Join Date: Dec 2016 Posts: 20 Likes: 0 Liked 0 Times in 0 Posts	Re: Chevrolet 8.1 Vortec advice Most trips are less than 250 miles, mainly in the Carolinas. Mixture of two lane roads at 50 to 55 miles per hour and highway/interstate 60 to 70 pending on traffic. At speeds of 50 to 65 it shifts a good bit but at 65 and quicker it smooths out. Before the tune any kind of grade change it would drop back to 4th, its not as bad now will drop to 5th and pull on.

01-03-2021, 06:11 PM	#7
Tom Meyer Senior Member Join Date: Aug 2003 Location: Pierce NE Posts: 934 Likes: 76 Liked 351 Times in 120 Posts	Re: Chevrolet 8.1 Vortec advice We tow with a 02 Suburban 3/4 ton 4l85E trans, 4.1 gears 265/65 /16 tires. We got about 7mpg. This last year got rid of the cats put in a balance tube up front and a flowmaster cat back system on. From there we went on a wheel dyno for the tuneup, picked up 50 lb of toque and 40 hp at 2300 rpm. It has great power towing but now gets 7mpg. We will be doing a intake mod [google 8.1 mod] have the intake done just need to install it. I just do not think these almost 500 ci motors are made to get mileage, but they pull great and are cheaper to maintain than a diesel. Tom __________________ Tom Meyer 5240 SS Stock ??? Last edited by Tom Meyer; 01-03-2021 at 06:16 PM.

01-05-2021, 06:33 PM	#9
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,416 Likes: 519 Liked 330 Times in 178 Posts	Re: Chevrolet 8.1 Vortec advice supposedly the OEM air induction system(filter ,tubes ,air cleaner box) is more than adequate to handle the 8.1 it's the opening for the throttle body that is the restriction---the cold air actually makes the engine WANT more fuel so with an increase in fuel consumption AND power while you get a decrease in MPG. Second use lots of synthetic fluids in the rear , trans if you can and engine oil.---third put a tonneau cover or a cap on the bed to help smooth out the air flow over that open bend---maybe put a chin spoiler under the front bumper to help smooth that area out-----then change to a 3:73 rear from that 4:10 to cut down on RPM 's at cruising speed --and finally maybe either a nose cone on the front of the trailer and or a spoiler on the top of that cap to move the air up and over that flat front of the trailer---FED 387

01-05-2021, 11:37 PM	#10
Tom Meyer Senior Member Join Date: Aug 2003 Location: Pierce NE Posts: 934 Likes: 76 Liked 351 Times in 120 Posts	Re: Chevrolet 8.1 Vortec advice Cruse rpm 2300 to 2500 65 to70 mph peek torque was at 2500. Taller rear tires can help with gearing. We have over 200 k on the clock still going strong. The hole in to floor of the intake floor is the restriction, Tom __________________ Tom Meyer 5240 SS Stock ???

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