Questions about rough estimate of fuel mileage of my application

[Powellbr]

Hi all, this is my first post on here and I was wondering what kind of fuel mileage I can expect to look at with my application. I'm either going to build a turbo'd 350 gen 1 chevy or a combination gen 4/5/6 502 chevy, either option will have multi-port injection from FAST and a distributorless ignition system from efi connection with granatelli motorsports Malevolent series coils that are rated at an 85,000 volts spark. I'm aiming at 650~700 horsepower on 30 psi of boost. No matter what engine I do build though, it's going to go into my 1993 extended cab short bed Chevy Silverado 1500. I'm going to swap the factory 4l60e to a fully manual 4l80e that's going to be built with metal clad seals, alto red eagle clutches & kolene steels, a billet input shaft, and the Transgo stage 3 shift kit. It's going to be coupled to a ford style Np205 transfer case built with a gm 32 spline input shaft, billet bearing retainers,and a rear slip yoke eliminator kit.

Rear axle is going to be a Torq 14 bolt axle housing with 40 spline 300m axles, an ARB air locker, six lug wheel hubs, Deaver long travel springs, and shackles that allow for up to 18 inches of travel. Front ifs will consist of an AAM 9.25" diff with upgraded axles, an ARB air locker, RCV axles, and a Vegas Desert Fab 4 wheel drive long travel kit that will allow for up to 15 inches of suspension travel. Truck will also have 4.10 gears in both axles.

Fuel system will consist of either a 25 gallon tank and a 42 gallon tank mounted behind the rear axle in between the frame rails or 2 25 gallon tanks with the 42 gallon tank up and behind the rear axle with electric fuel pumps in the tanks with a swirl pot to lessen the chance of fuel starvation.

Wheels will be 17x9 Ultra nomads with beadlock rings, tires will be 40x12.5x17s Pro comp Xtreme MT2s.

Thanks in advance, I know it's a long post but I've got a lot of work that I'm going to do

[LittleBlackDuck]

Hmmmm, lots of weight, lots more power and even more drag....

I would not like to think about the fuel consumption. Sounds like a lot of extreme offroad action.

Simon

[Powellbr]

Yeah, it's a brick, I realize this, however, I'm going to partially gut the interior, removing the carpeting, lighter fiberglass dash, I'm going to replace the factory core support with tubing because I'm going to be converting the front end to a 99-07 fiberglass one piece clip, it's already got fiberglass bedsides because it's a stepside, I may replace the windshield with pre tinted lexan, I'm going to cut out all unnecessary metal in the engine bay both for room and weight savings like the wheel wells, I may cut out the factory bed floor and replace it with aluminum sheeting, I'm getting rid of the factory bench seat in the front and replace it with lighter reclining racing seats, currently I'm considering deleting the heater core and rebuilding the factory a/c system or I'll delete it depending on the price, I'm going to rewire the truck with a system from Infinity wire so that I don't have to run wires from all corners to the truck to the other corners, idk what else I will be able to do though after that, I'll have to see after I get my truck back. Thanks in advance.

[mcrews]

why?

why do you care what the mpg is?
Why are you posting here?
Why are you naming all the parts like a 'brag list'?
why would we care?

just as an example, you said: "I'm going to swap the factory 4l60e to a fully manual 4l80e that's going to be built with metal clad seals, alto red eagle clutches & kolene steels, a billet input shaft, and the Transgo stage 3 shift kit. "
What does the part in red have to do w mpg????

here, let me answer.....nothing.

Maybe.....if you mentioned " I drive it 30 miles a day, 1/4 streets and 3/4 freeway" then someone MIGHT be interested to help you.

But here's my advise......buy a scangauge and figure it out yourself.

[mcrews]

oh yeah......
ps. air your tires up to 45+ psi to get better mileage for free.

[ksa8907]

Im with mcrews on this one, when you're done putting $20,000+ into your truck then we will know you're serious.

Also, if you're building a v8 and running 30 lbs boost i sincerely hope you'll be making a lot more than 650 hp.

[me and my metro]

Our stock car back in the 70s got 3mpg. I'm not sure the new ones get any better.

[Gasoline Fumes]

I estimate 5 MPG downhill.

[redpoint5]

While I agree with Mcrews points, don't let that scare you off. He's normally that friendly.

Weight generally won't effect MPG much, especially in a big truck. Your biggest factors going against MPG is the huge powerful engine, huge and inefficient aerodynamic shape, and the huge tires with massive rolling resistance.

My WAG is 10 MPG, give or take 4 MPG. Doesn't matter though, because no reasonable person would daily drive this. Just build it and have fun. For kicks, let us know what MPG you average once it's done.