lets talk air filter CFM...

[GWBourne]

what is the factory filter setup rated at? what are the demands of a factory HX-35 pushing 45lbs of boost?



im looking into other filter systems to include the BHAF and was wondering about CFM as i think i found some new ideas, but need to do some homework before i get excited.

thanks.

Grant

 

[Tryingit]

There was some talk about this awhile ago. It would seem that the BHAF is not a high flow filter. The larger surface seems to be for longer service intervals. If you do some searching one of the members has already done some homework. There are some like the AEM Brute force dryflow that has testing to back a over 900cfm. I believe the stock airflow is somewhere around 400cfms. I'm noe expert but I've done a little homework myself.

 

[JRD]

One thing to remember when talking cfm flow... what you gain in cfm flow CAN be related to its filtering capabilities. Id like to see the AFE PG7 VS Stock VS paper BHAF in flow and filtration.

 

[jwilliams3]

There is a thread in products and accessories that says the Dryflow is not even flowing as much as a drop-in replacement.

The BHAF is a marginal increase in flow.



My suggest is at least a 5 layer drop in from AFE or the Proguard 7 stage 1 or 2.

 

[johncameron]

Ya but a BHAF looks cool when you open the hood!!

 

[Bob4x4]

Ya but a BHAF looks cool when you open the hood!!

I don't think so :-laf



Bob

 

[cerberusiam]

It would seem that the BHAF is not a high flow filter.

Somebody is blowing smoke and sucking air with that observation, and it ain't thru the filter.



Stock filter is rated at 400 cfm, but unless you open up the air box you won't see much over 350 cfm. To say the BHAF is only a marginal improvement over stock is ridiculous.



FleetGuard AH19037 is rated at about 690 cfm. The marine version, AH19004 is rated at 920 cfm. The rest of the BHAF filters fall some where in between these two. If those aren't hi-flow compared to the stock setup I would say there are some unrealistic parameters being used.



As far as what is needed for air flow, you can calculate CFM based on (displacement) * (rpm) / 3456.



So at 0 boost; 2700 rpm x 359CID / 3456 = ~ 280 CFM.



Assume standard atmospheric pressure of 14. 7 psi, at 29. 4psi you would have 3 times as much air and need 840 CFM. The relationship is not linear but it will get you close enough for planning.



Figuring 45 psi of boost gives us about 1120 CFM for needed air flow.

 

[GWBourne]

One thing to remember when talking cfm flow... what you gain in cfm flow CAN be related to its filtering capabilities. Id like to see the AFE PG7 VS Stock VS paper BHAF in flow and filtration.

this is a good point, and i have to double check some numbers, but the filter i am looking at flows a LOT and has a low micron filtration number. ill get more into it once i get some solid numbers on what is needed for flow... .

 

[GWBourne]

There is a thread in products and accessories that says the Dryflow is not even flowing as much as a drop-in replacement.

The BHAF is a marginal increase in flow.



My suggest is at least a 5 layer drop in from AFE or the Proguard 7 stage 1 or 2.

ok, sugestions and opinions here... . :-{}



im looking for SOLID flow numbers from the factory... anyone?

 

[GWBourne]

It would seem that the BHAF is not a high flow filter.

Somebody is blowing smoke and sucking air with that observation, and it ain't thru the filter.



Stock filter is rated at 400 cfm, but unless you open up the air box you won't see much over 350 cfm. To say the BHAF is only a marginal improvement over stock is ridiculous.



FleetGuard AH19037 is rated at about 690 cfm. The marine version, AH19004 is rated at 920 cfm. The rest of the BHAF filters fall some where in between these two. If those aren't hi-flow compared to the stock setup I would say there are some unrealistic parameters being used.



As far as what is needed for air flow, you can calculate CFM based on (displacement) * (rpm) / 3456.



So at 0 boost; 2700 rpm x 359CID / 3456 = ~ 280 CFM.



Assume standard atmospheric pressure of 14. 7 psi, at 29. 4psi you would have 3 times as much air and need 840 CFM. The relationship is not linear but it will get you close enough for planning.



Figuring 45 psi of boost gives us about 1120 CFM for needed air flow.

thank you VERY much for the info you have provided. it will help BIG time.

Grant

 

[Bob4x4]

The flow numbers must be at the same restriction to be valid ! The numbers that have been quoted here have not been shown on a dyno. At our last club dyno event we gained hp by swapping to a AFE from bhaf.



Bob

 

[GWBourne]

The flow numbers must be at the same restriction to be valid ! The numbers that have been quoted here have not been shown on a dyno. At our last club dyno event we gained hp by swapping to a AFE from bhaf.



Bob

100% valiad point, and i have considdered this. i mainly needed a base number to go off of. thanks again.

Grant

 

[Morse]

I found out a person should be concerned with air filter size the hard way. . I had a 5x12'' AFE filter on my twins setup, and it sucked together. . Needless to say, I just had my big brother rebuilt. . II did the rebuild, and made it some sort of Hybrid. . While they were at it, they went throught the SP 66, and made it a SPS 66. I also bought a 6'' inlet, 24'' long filter. . Should be better now. .

 

[cerberusiam]

The flow numbers must be at the same restriction to be valid ! The numbers that have been quoted here have not been shown on a dyno. At our last club dyno event we gained hp by swapping to a AFE from bhaf.



Bob

Not sure what numbers you mean but the ones for the filters listed are from FleetGuard and have been proven way too many times to question. The formulas are what they area. Proving or disproving is meaningless without a lot tighter control of the experiment.



The same can be said for club dyno event claim. Too many unknowns to put any credibility or emphasis on it. Air flow is only part of the equation and dyno runs do not mirror real world conditions very well. Gaining HP does no good when the loss of filtration comes back to haunt a person.



What would be invaluable is some comparisons on air flow at different restrictions and the filtration numbers to go with it.

 

[Bob4x4]

Not sure what numbers you mean but the ones for the filters listed are from FleetGuard and have been proven way too many times to question. The formulas are what they area. Proving or disproving is meaningless without a lot tighter control of the experiment.



The same can be said for club dyno event claim. Too many unknowns to put any credibility or emphasis on it. Air flow is only part of the equation and dyno runs do not mirror real world conditions very well. Gaining HP does no good when the loss of filtration comes back to haunt a person.



What would be invaluable is some comparisons on air flow at different restrictions and the filtration numbers to go with it.

Air flow is always measured at some restriction level... ..... inches of water or inches of mercury. Cummins DOES NOT measure filtration directly. They measure it with oil analyisis. The same way I did when I went to the AFE set-up. My numbers have always come back at or better than stock filters. I do a bit of off roading so I was concerned myself. After a few oil analyisis results under differing conditions I am now satisfied my filter is doing its job. My old 12 valve is syill running better than new and the 05 is happy also.

I have seen too many hack install jobs with the bhaf to recommend any one use it. Most end up resting on the filter mounting studs with holes worn through. Enough said



Bob

 

[cerberusiam]

Air flow is always measured at some restriction level... ..... inches of water or inches of mercury. Cummins DOES NOT measure filtration directly. They measure it with oil analyisis. The same way I did when I went to the AFE set-up. My numbers have always come back at or better than stock filters. I do a bit of off roading so I was concerned myself. After a few oil analyisis results under differing conditions I am now satisfied my filter is doing its job. My old 12 valve is syill running better than new and the 05 is happy also.

I have seen too many hack install jobs with the bhaf to recommend any one use it. Most end up resting on the filter mounting studs with holes worn through. Enough said



Bob

Gotcha!! Thanks for the info and insight.

 

[CTieman]

Check out the Amsoil drop in stats on their website. This is a dry filter so maintaining it is very easy, especially if you're in the middle of Baja, just pull it out and tap out the dust.



The filter minder will suck in about half way with the stock box and new filter. My filter minder hasn't moved since I did the home made cold air intake in the last TDR issue. Remember you loose about 5% hp ever 30* increase in intake temp (BHAF)