Inliners International Forums General Discussion Hi Performance cfm on efi

Here's a formula that might help guide you in the right direction.

CFM= (max rpm x cid) / 3456

So, if your redline is 7000rpm with a 250cid engine,
your max CFM is ...... 1,750,000 divided by 3456 ... or.... 506.365 CFM. That's not to say you need to only run a 500 cfm throttle body. It's just a guideline.

My book states this is for a turbocharged engine, but it will give you an idea. The 0.55 figure is the "maximum load brake specific fuel consumption (bsfc) of a typical turbocharged engine."

pounds of fuel per hour per injector=

(expected bhp x 0.55) / number of injectors

so... 500bhp x 0.55 = 275

275/ 6 (I'm guessing you're going to run 6 injectors) = 45.833 lbs an hour per injector

Like I said, I just posting this as a guide so when you talk to a fuel injector company y'all will be on the same page. Good luck. John