MPG on a 521 700hp

I'm trying to figure out how big of a fuel cell I need. Would you think the engine would get 5, 7-1/2 or 10 mpg's? My current setup in the truck will only go 100 miles and that seems to be the very minimum. How far do you reckon I could make it on 22 gallons?

This is a 4x4, c6, 521cu 700ish with 1150 carb, 31 or 33" tall tires with 3.50 gear ratio.



I appreciate your input,

700 hp x .5 for a NA motor = 350 lbs/hr for fuel.

SandHillsHillbilly wrote:700 hp x .5 for a NA motor = 350 lbs/hr for fuel.

That would be 58 gallons per hour. Solves that, might as well just go with the 22 gallon because I couldn't put a larger enough tank to drive it very far!

That makes sense.
I can drive to the closest towns and local dragstrip with 100 mile range but if I wanted to drive to the local 1/4 mile strip or local mud park I would have to make multiple fuel stops. I was hoping there would be someone with a simular setup that might could tell me what type of MPGs they got.

I plan on buying a tow truck once I complete this project but I would still want to drive to the local car shows and the events that require you to make road trips to compete in.

Go with the biggest cell you can fit.  Too much capacity is never a problem.  With my ~500HP 429, 12-14 mpg is pretty typical on the interstate, and I still carry an extra 5 gallon can or two in the trunk with the 22 gallon cell.

For what it's worth, I used to have a car with a computer that registered instant and average mpgs, and watching the instant mpgs while climbing long hills revealed that light load with higher rpms and less throttle opening was much worse than heavy load, low rpms, and wide throttle opening.

Carl wrote:Go with the biggest cell you can fit.  Too much capacity is never a problem.  With my ~500HP 429, 12-14 mpg is pretty typical on the interstate, and I still carry an extra 5 gallon can or two in the trunk with the 22 gallon cell.

For what it's worth, I used to have a car with a computer that registered instant and average mpgs, and watching the instant mpgs while climbing long hills revealed that light load with higher rpms and less throttle opening was much worse than heavy load, low rpms, and wide throttle opening.

Thats good info!

My original plan was to build a stainless steel 14ga 36x36x10 fuel cell with internal baffles, straight tube sending unit and some bungs. My second idea was to make a fuel cell in the bottom of an old UWS tool box I have for the truck and that might even be easier than just a fuel cell in the bed.

But how will I hide the sound of the engine! LoL

Baffles aren't really necessary, just fill the cell with foam to keep the fuel from sloshing around. Also keep in mind that a tall cell gives you access to more fuel than a flat cell. My 22gal is only 10" tall? and 20 gal is about all I can get out of it before it starts sucking air.

I use to have a toolbox that was made with a 40(or 60 cant remember) gallon fuel tank under it. had a filler neck in the bed and you just turned the factory front filler neck up to hook to the bottom of the toolbox tank. could've easily been converted to a stand alone tank.

Carl wrote:Baffles aren't really necessary, just fill the cell with foam to keep the fuel from sloshing around.  Also keep in mind that a tall cell gives you access to more fuel than a flat cell.  My 22gal is only 10" tall? and 20 gal is about all I can get out of it before it starts sucking air.

Good point about the box shape.