rgp

I have been looking at a air/water intercooler for a first gen 5.9 but I cant find any spec giving the cfm requirements of the motor/turbo. Any help would be great. Thanks

Richie O

My 57/64/14 S300 is rated for 870 cfm's. It is a middle of the road turbo.

RSWORDS

So...

5.9L = 360 C.I. and we will assume you turn 3200 RPM TOPS


333.33 CFM thats the Volume of air. The Mass depends on temps, boost, ect

For more info Click here

unixcowboy

That's naturally aspirated - -
Forced induction - turbo or mechanical blower - increases that...

You need to increase it for every 14.7 lbs ( normal air pressure ) of boost.

So : 333.33 at 29.5 lbs of boost = 999.99 cfm or ~ 1000cfm.

Richie O

That sounds more like it.
I would go for the high end cfm's. You don't want a cooler taking air away because of a restriction. Been there done that. I kept adding fuel and my boost would not go above 22 pounds. After pulling out my hair I figured out the small aftermarket air to air would not flow the cfm's needed. It was an old banks unit put on in 90 by the original owner of my 89. Worked great at lower fuel settings.

RSWORDS

You can only put one cubic foot of air in a 1'x1'x'1 box. does not matter if it is at 20psi or 100psi... It is still 1 Cubic foot of air. The mass of air (what you are talking about, lbs of air per min) would be different under boost. Whole new board game. this explains all.

http://www.dieselbombers.com/general...tml#post246394

Richie O

I don't doubt the math but to me it makes sense that a turbo equiped engine has lots more cfm's entering the engine than a natural. I read that link and the info went way way over my head. I think I get it. I was thinking a cfm of air was measured at atmospheric pressure. I thought you could take 10 cfm's of air and compress it into 1 cubic foot and still have 10 cfm's just under pressure.

RSWORDS

CFM = Cubic Foot per Min Its a unit of volume. If you had an air tight box 1'x1'x1' you have 1 cubic foot of air. If you put an air hose on it and bring it up to 100psi you still have 1 Cubic foot (size of the box does not change) but the Mass of the air changes... ALOT. 1 Cubic foot will always be 1'x1'x1' never less, never more Think of it in how much room it takes up. A cylinder can only take in a certian volume of air (bore x stroke) you can pressurzie it as much as you want but it will still take up the same amount of air... I know... VERY confusing. VERY BERY confusing... Took me a while to figure it out and I STILL second guess myself ALOT. Both of them need to be looked at while sizing things.

Robert Wilbur

Fair enough however if engine moves 300cfm @ 5.9l per minute at an idle and natural air pressure

As you compress it from the turbo forward the system before the turbo now has an ability to consume more per minute thus needs to provide more?

At the turbo the pressure is compressed from a specific volune then the cylinders compress from said volume of which will vary if the supply per minute is choked or stays the same

Simply putting more atmosphere in said space doesnt require more cf, however the cfm will change based on how much you change the cfm due to rpm and psi limitations

In a space of vacume whats the speed of incoming air and it what point does pressure equalize. It doesent in this case or there would be no vacuum at the intake

Sorry unnecessarily spoken its just the explaination is convincing but doesnt seem complete more cfm to the intake can help supply demand at pressure point but still limited by turbo intake side