j_k_auto

I am trying to figure out what cfm I might be using with a stock turbo at 30 psi & 40 psi?

Here is what I found out but how do you add boost to the equation?

https://www.dieseltruckresource.com/...56&postcount=3

I show it would be 417.82 according to this figure at 4000 rpm but what will the number be with the boost?

BigErksG2

that looks like a naturally aspirated cfm. you would have to find out how many cubic feet at sea level barometric pressure is equal to 417 cubic feet at 30 psi. reminds me of the old physics days!

j_k_auto

I am trying to learn here and it don't make sense to me. I am just trying to figure out my cfm on my truck be honest. That is with 30 psi of boost that is.

66gaza

Fleetguard's formula for working out airfilter cfm for a 4 stroke diesel is CID X RPM X VE / 2556 . VE for a NA diesel is 0.85 and for a turbo ranges from 1.3 to 1.8 these are the only figures they give so not sure exactly how it equates to PSI. so 359x4000x1.8/2556=1011cfm...now thats alot of air. A BHAF wont pass that much, the AH19037 BHAF is rated at 680cfm at 8". There is another factor, Pulsation Factor (PF) - only applies to engines that are both naturally aspirated and having 3 cylinders or less. Hope this helps.
Just looked at Enginaire's website and there formula is slightly different they use 3456 enstead of 2556 which I think is the same as the figure posted in your link Even the experts can't seem to agree. I would go worst case scenario and your covered.

Gaza

j_k_auto

yes this does help. So I wonder what air filter will work to put out 1200 cfm of air then. Now I think I get why the track trucks don't use air filters they need more cfm then the air filter can actually handle...part of the reason that is...

66gaza

There is another BHAF that flows 920 CFM at 8" its a AH19004 it is more $ though. I would think you would be looking at some of the AFE filters for more CFM. The AFEs are reuseable too. I would think this has been discussed on here before by people who know more than I do about it.

Gaza

j_k_auto

I agree I am searching several areas on this matter and I thing I am going to use the aem dry filter 21-2059dk and make a box for it since they never made a unit for my truck. I just want to make sure I have enough room if I go this route.

Oh here is some reading on the cfm s&b came up with.

Look at page 13 and it shows what cfm the filters are tested. Now I am not sure how much higher cfm the engine will go though.

http://www.sbfilters.com/pdf/news_pd...low%20res).pdf

Lil Dog

When they talk about filter flow, it has to be to a standard draw pressure from the filter too, which I haven't seen posted. The pressure drop will increase with flow through the filter increasing to a point then it goes exponential. I would assume they use -10" H2O? Thats what the filter minder is set for.

Unless you are running twins, you wouldn't be into the 4 digit mark for flow.

66gaza

A 12 valve head wont consume twice as much air turning 4K as it does at 2K as the head isn't efficient enough. Also there are lots of people running twins and a BHAF without problems.

Gaza

66gaza

LiL Dog, the BHAF are only rated upto 8" on the Cummins site. 8" was mentioned in an earlier post, but you are right gotta compare apples with apples.

Gaza

j_k_auto

Well I just got off the phone with aem and the filter they offer will flow 1350 cfm.... So I think that would be good foe what ever I need it for.

Lil Dog

Hey, thanks for the info..

j_k_auto

Yep thanks for the info. Now I have to check out the s & b filters because now or soon they will offer the dry filter also. So basically I guess all 3 filter companys will have dry filters...which one to go with...