About how much percentage airflow do you gain with each drop in pulley size? 10% 15%, anyone know? I need to know for fuel reasons. Need to make sure I'm going to have enough fuel flow.

 

14.90% of air "compressed" in to the blower. CFM will drop with higher pressure btw.

however i used a 33.333% reduction per psi due to heat of compression.

Keep in mind that there will also be a bellcurve of loss due to the eaton adding to that heat.

My baseline for the oxygen/air was under standard temp and barometric pressure. It will change greatly because you add alot more dynamics.

 

thanks, been waiting on an answer for a few days now.

 

Well my calc will be off up to ~7% because of extreme heat/pressure but its a good baseline.

 

Ideally;
Flow (L/min) = RPM*(6.25"/pulley diameter)*1L/rev

BTW, ralliartist, I went though my PM's again... I think i told you the wrong number for the stocker... it should be about 470cfm.

 

yea there is a whole thing on the whole CFM calculation in the Rebel Engineering's New Intake Manifold about 4-6 pages in.

Problem though here is...

When you increase pressure you lose cfm. eg: if i inflated a tank to 100 psi i will only get about 5-6 cfm out of a standard work hose that you use for power tools.

If I inflate it to 60 psi, i get about 7-8 cfm.

Problems occur when temperature and psi are added in the mix. Gets bogglesome.

 

Yeah, the blower does work harder, in turn moving less air. Hence why I put 'ideally' before the equation.
It's not a bad equation for first step estimations though.

 

you two have been a big help. Thanks a lot. I got a good "estimate" of what to expect now.

 

yea as much as i dont say anything, omega adds alot to convos when i pissed him off earlier and had him cough up some info....

Gonna have to work on area47 a little harder though, he doesnt put his ego on the line

Still good group of folks.

 

just for reference, I should be almost doubling cfm's with the port work and 2.9 pulley. I even took into account heat and used lower numbers than the 14.9%. It's just an estimate, but I think it should be pretty close. Probably be over 800cfm's.

 

could use this to help aid your "heat/inefficiency bell curve"
Basically took the engine rpm with the chart omega gave me for the eaton, and then plotted it with the map from eaton's efficiency graph

 

eww, NICE! Thanks man, that's a awesome graph. Wouldn't be hard at all to plot what I want to know!

 

Nice chart!

 

yes, very nice graph! What program did you use to creat that?

 

I did it manually....hence why only 2 were plotted since it took a couple hours.