Chevrolet 8.1 Vortec advice - Page 2

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

FED 387 · 01-06-2021, 11:58 AM

yes taller tires will help cut down the rpm---depends whats available might only lower it a smidge to say a 4:00 not much but it will be better than what you have now

Bob Don · 01-07-2021, 09:01 AM

Quote:

Originally Posted by C29404

Bob, was your pick-up stock and did it hunt between gears when towing at highway speed?

Pick up was stock. No gear hunting on highway except for going up hill.

C29404 · 01-07-2021, 06:32 PM

55 to 60 miles per hour its around 17 to 1800 then at 70+ 2200 and up.
I currently have a 285/70-17 wheel and tire combo on it, when I bought it it had the 245/70-16 wheels and tires, changed them for towing stability not so much for looks. I've also got a camper shell/cap on the bed. I have looked at the profile of the truck versus the trailer and there is a lot of flat trailer showing around the edges, one of those bubbles may be in the cards. I also stumbled across the manifold modification a while back, if I can find another manifold to modify i'll give it a try. I appreciate all of the input I have received on this matter and I am going to give some of this a try. Thanks

01-05-2021, 06:33 PM	#11
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,412 Likes: 513 Liked 329 Times in 177 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	#12
Tom Meyer Senior Member Join Date: Aug 2003 Location: Pierce NE Posts: 934 Likes: 75 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 ???

01-06-2021, 11:58 AM	#13
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,412 Likes: 513 Liked 329 Times in 177 Posts	Re: Chevrolet 8.1 Vortec advice yes taller tires will help cut down the rpm---depends whats available might only lower it a smidge to say a 4:00 not much but it will be better than what you have now

01-07-2021, 06:32 PM	#15
C29404 Junior Member Join Date: Dec 2016 Posts: 20 Likes: 0 Liked 0 Times in 0 Posts	Re: Chevrolet 8.1 Vortec advice 55 to 60 miles per hour its around 17 to 1800 then at 70+ 2200 and up. I currently have a 285/70-17 wheel and tire combo on it, when I bought it it had the 245/70-16 wheels and tires, changed them for towing stability not so much for looks. I've also got a camper shell/cap on the bed. I have looked at the profile of the truck versus the trailer and there is a lot of flat trailer showing around the edges, one of those bubbles may be in the cards. I also stumbled across the manifold modification a while back, if I can find another manifold to modify i'll give it a try. I appreciate all of the input I have received on this matter and I am going to give some of this a try. Thanks