400+ hp chevy 350 how much mpg?

Christian... I thought you was smarter than that.

600 cfm is perfect for 400 HP. Heck I made 505 HP at crank with a 600cfm carb.

The cfm has NOTHING to do with fueling.. It airflow

Needed carb cfm = rpm x displacement / 3456 x 0. engine VE %. His engine should be around 93% VE

At 6500 RPM he would only need 612 cfm, at 6000 rpm only 565 cfm

He would have to spin the engine to 7,500 rpm to need 700 cfm carb

How do you find it hard to belive he could have 9.9:1 compression?? This is simple math. Its the 6cc flat top pistons, 62cc heads, and .016" gaskets

I have 10.4:1 compression with 64cc heads, 5cc flat tops, 355 cid

To the asker.. Kevin...

Your alittle off on your compression though.. It's 9.88:1

How did you end up with .045" deck height? Thats killing you man.

Sounds like you bought cheap rebuilders pistons. They are know for have the shorter compression height

That combo should be good for 400-420 HP and get you about 16-17 mpg city and 20-22 highway

I'm guessing your engine is already together? If not, please send those pistons back and get some with the correct compression height that puts them .020" to .025" in hole at TDC

Your losing all benifits from the quench design. You need that tightened up to .040" rather than your .061" now.

If you did that, you would pickup 10 HP and close to 1 mpg, plus could run lower octane fuel with out detonation

400 Hp 350

"bolt on" parts such as exhuast, intake, pulleys, high flow filters, and a flex fan are all very simple and easily done. but you can only get so much out of them. 350 hp is about tops for bolt on performance with that starting point. you want 350 PLUS hp, you got to get inside the motor. already lots of good suggestions on top end parts for that motor. supercharger and major hp, you should of gotten a motor meant for supercharging and making major power to begin with. would of been cheaper..... you will need to open up the motor and do plenty of other things before adding a supercharger if you want it to truly perform and not just kill the motor. nitrous..... some poeple think you just add a tank of NOS and spray it in the motor, and everything is good. not true. NOS allows an engine to make more power for two reasons. 1. it supercools the air, allowing a denser charge in the cylinder (denser means more air molecules in the same space). 2. it adds extra oxygen. more oxygen means you can get more fire. but this useless if you dont add extra fuel to be burned with the extra oxygen. it can even be worse then useless. a cutting torch works by putting out more oxygen then can be consumed by the fire...... inject enough oxygen into an engine and you can create a cutting torch inside the engine. for best results, you need a secondary fuel injection system hooked up with the NOS. when the NOS injects, extra fuel goes in too. 14.7/1 is the ideal air/ fuel ratio normally. with NOS being added you want 8/1 instead. this gives you the most power while actually being more gentle on the motor. and for larger shots of NOS, you also want a controller. you dont want to add 100+ hp in an instant, you want to take a second and build up to it.

Nice engine, well designed, and well done, but I need to know what car it is being put in to know about how many mpg you might get...the weight of the vehicle, the type of transmission, and the final drive ratio are also important. In an early Chevelle, or chevy 2, with 308's and a 4 speed should get you 12 around town, and 18 on the highway, if you keep your foot out of it, less if you have a heavy foot.

If you know enough about engines to know what all that crap you typed means, then you sould already have a pretty good idea as to what kind of fuel consumption this thing is gonna require. Just guessing, I'm gonna say 12 MPG if you take it easy, 10 if you like to hear the pipes ring.

how are we going to know ???

car ???

rear end gear ???

transmission ???

and a 600cfm will have a hard time fueling a 400+ hp engine, you would need at least 700 cfm's like form a Holley 3310 vacuum secondary carb

that cam is only capable of pumping out 342 hp anyways

and I have a hard time believing you are getting 9.9:1 compression anyways

We need to know what it's installed in and what the rear end ratio is.

I have a 426HP stroked TPI motor in an IROC, and with the 2.73's it actually got about 19. Now that i hav put 3.42 gears, it dropped to about 15..

I'd bet though, with a carb on it you will be lucky to see 15.MPG.

Spend 3 grand on a motor and cant buy gas? Mommy will help you. Dreamin!

The MPG is extremely easy to find out, just drive the car.

you could use a car performance simulator to virtually tune your car with all this mods and run simulated MPG tests as well as dyno runs but requires some knowledge for your part too, give a try at http://www.nxgtrsim.com/