[Orb]

I did some hand calculation of the volumes of the air box today and based the flow ranging for 500-800 CFM. The worst part of the air box is on inlet side a mid point of the filter. There not much more 4.52” (3” in length) of clear space at the mid point so the pressure drop are based on half the flow (which it isn’t) so it the worst case. The estimated pressure drop at 800 CFM is about 0.08 PSI so not that much but it is a very short distance. The other larger restriction is the filter but stock flow should be about 3" H20. One thing for sure is filter with less pleats is not going to fare well in this air box design. The design is optimized in having the pleat in specific orientation for increase cross sectional area and flow.

The pressure drop at 700 CFM is well below 0.45 PSI (I’m being every conservative) given I have taken in account the type of bends, geometry shape and filter restriction (extrapolated estimate). I would have to do an in depth study on the bends to get a true number but I just can’t see the air box and filter restricting any more than what I have stated. The pressure drop I have stated should be used as a sense of scale and not absolute so don’t take this more than opinion. I don’t believe there are big gains here unless we are just getting outside on the compressor efficiency range. Also keep in mind that the gain form cotton filter of 5-8 WHP for PROcede v2 equals to about 0.07 PSI reduction.

The main reason I looked into this as I was convinced that my K&N filer was causing a loss and my dyno butt can tell difference when I changed the filter back to stock and noticed right away. What is odd with the K&N design is the pleats are in the opposite orientation compared to the stock filter so there is loss on cross sectional area in the worst possible place in the air box and to make matter worse the flow path is far less than optimal so there is a lot more pressure drop.

I know many of you think dyno are the end all but in this it like tapping in finishing nail with 100 lb sledge hammer. It doesn’t have the resolution and only one person (Driver72) kept track of the pressure for filter testing so the rest of the data is….well…worthless.

If you have PROcede v2 and new IC it is unlikely you going to get a more with a new air intake but let see how it play out.

I was goping to make the 335i better i hit evey combined flow pipe less than 2"-2-1/4" diameter for replacement. Cheap and will be highly effective in increasing possible boost level and power.

Orb

Edit: The BMC filer has the pleats in the same dirrection as the stock filter so it should do better than the K&N but lacks surface area for optimial flow. I wouldn't consider a foam filter for this box either.

[rambino]

Very Interesting,

how can we improve the stock airbox, some of us here in europe arent allowed to have cold air or direct filter intake setups

[Panoz]

Very nice post...Lets see how it will turn out with the new BMW Performance Air filter. This supposed to increase the air flow by 25%.

[TurboBullett@Ambient Thermal Management]

you are reiterating what we have found in our testing that... the stock airbox isnt bad at all. what is needed is a higher flow element for testing(stainless mesh). this new panel should have the pleats running in the same orientation as stock but also be a little thinner on the bottom side as the stock filter doesn't provide enough clearance under the filter. another possible change that can be made with a custom panel is a thicker gasket edge so it spaces the top of the box up a little higher. Lastly providing a positive pressure source to the factory inlet duct would also pay dividends at speed

[tek818]

has anyone inspected the gruppe M design? I'm curious what that looks like inside...

[munters]

Originally Posted by TTurboBullett

you are reiterating what we have found in our testing that... the stock airbox isnt bad at all. what is needed is a higher flow element for testing(stainless mesh). this new panel should have the pleats running in the same orientation as stock but also be a little thinner on the bottom side as the stock filter doesn't provide enough clearance under the filter. another possible change that can be made with a custom panel is a thicker gasket edge so it spaces the top of the box up a little higher. Lastly providing a positive pressure source to the factory inlet duct would also pay dividends at speed

Are you going in this direction with your intake? Or are you going the same direction as the others... (I dont like the open conefilter design)
I like it the best, if you cant see right away someting is different.
Should look and sound like stock as possible but bee a badass...

Thanks

[fotiki]

Originally Posted by Panoz

Very nice post...Lets see how it will turn out with the new BMW Performance Air filter. This supposed to increase the air flow by 25%.

There is no BMW Performance Air filter, you must mean BMW Performance air intake ... a friend of mine is going to put it, ill tell you impressions

[cn555ic]

So what you are saying is the BMC filter is better than the K&N filter?

[hotrod2448]

I didn't do all the fancy engineering guesstimations but, years of building race cars tells me the intake can be better.

If a reduction of .07 results in 5-8hp and there is potentially a .45psi drop, that says there is room for more improvement.

[cn555ic]

If the K&N pleats (folds) are in the opposite direction of the cover than I can see it being more restrictive than not because if you look at the underside of the filter cover, there are many grooves that I guess allows air to flow...If the folds of the filter you place in there goes in opposite direction, what you are doing is actually making less surface area for filter to allow air to pass...It will look like a bunch square boxes instead of the actual design of long linear rows...I didn't even realize this until this post that the K&N filter folds were in direct opposite direction to the OEM filter...I would also have to conclude without any data, but just my opinion that it has to be doing less than good for the HP if the filter was constructed this way.

[E90ice]

Oh lord! Driver72 is going to have a heart attack!

[Orb]

Originally Posted by cn555ic

If the K&N pleats (folds) are in the opposite direction of the cover than I can see it being more restrictive than not because if you look at the underside of the filter cover, there are many grooves that I guess allows air to flow...If the folds of the filter you place in there goes in opposite direction, what you are doing is actually making less surface area for filter to allow air to pass...It will look like a bunch square boxes instead of the actual design of long linear rows...I didn't even realize this until this post that the K&N filter folds were in direct opposite direction to the OEM filter...I would also have to conclude without any data, but just my opinion that it has to be doing less than good for the HP if the filter was constructed this way.

Your observation are correct (but applies for top and bottom of the filter) and you just have to imagine that flow will take the least path of resistance so the air flow will naturally migrates thought the pleats without making a radial change in direction with the stock pleat orientation. It is a little tricky making sure your optimizing the surface area of the filter for a given flow rate. It is not an uncommon design either and have worked with something similar with a humidification membrane some years ago.

Orb

[Orb]

Originally Posted by hotrod2448

I didn't do all the fancy engineering guesstimations but, years of building race cars tells me the intake can be better.

If a reduction of .07 results in 5-8hp and there is potentially a .45psi drop, that says there is room for more improvement.

The improvements are likely to have diminishing returns for a new design. This is lot effort to get marginal improvements as the stock air box is not that bad. I was tiring to point out the reason there might be good improvements is because the turbos are at its efficiency limits and small pressure drop are hurting power output. You could target any other component in the intake track for reduced pressure drop and get the same results.

Orb

[midlife]

Originally Posted by hotrod2448

I didn't do all the fancy engineering guesstimations but, years of building race cars tells me the intake can be better.

If a reduction of .07 results in 5-8hp and there is potentially a .45psi drop, that says there is room for more improvement.

i am at over 8,000 feet and am ready to pull the trigger on a cai.

even ASSUMING that at sea level a good cai may only be marginally better,
my guess is that at v high altitude it should help me alot.

do you guys concur with thinking of mine re a good cai at high altitude??

thanks

[Bubbles]

Thanks Orb for the informative post.

[Orb]

Originally Posted by TTurboBullett

you are reiterating what we have found in our testing that... the stock airbox isnt bad at all. what is needed is a higher flow element for testing(stainless mesh). this new panel should have the pleats running in the same orientation as stock but also be a little thinner on the bottom side as the stock filter doesn't provide enough clearance under the filter. another possible change that can be made with a custom panel is a thicker gasket edge so it spaces the top of the box up a little higher. Lastly providing a positive pressure source to the factory inlet duct would also pay dividends at speed

I would slope (20 degrees) and lengthen the pleats if I could and it will help to flow balance this design so it optimal filter media surface area is used under all flow conditions. Manufacturing this part this way is another story.

Glad to someone is engineering components instead of fabricate and releases with dyno that has more error built in than any gains or even losses.

BTW, I love to know what the air box pressure drop is at a few flow points.

Orb

[Lazzer]

Thanks for the informative post Orb.

So a question then, when increasing boost is there a point where the stock air box becomes restrictive?

I always see posts regarding the Procede V2 and people saying that it will never make 400 whp with the stock air box. So are we to assume at 14-15 PSI the stock air box becomes restrictive?

[Orb]

Originally Posted by Lazzer

Thanks for the informative post Orb.

So a question then, when increasing boost is there a point where the stock air box becomes restrictive?

I always see posts regarding the Procede V2 and people saying that it will never make 400 whp with the stock air box. So are we to assume at 14-15 PSI the stock air box becomes restrictive?

The flow rate assumption I used were for flow rates at 15 PSI but it is not with complete accuracy. I don’t believe the air box is major choke point at this time. The intercooler is a big choke point as we already know we can reduce pressure drop by 1+ PSI for 1200.00. It is always the sum of the components in the system that will dictate the behavior.

In short, I wouldn’t be buying a cold air intake form anyone unless they showed the difference in pressure drop between the systems. I doubt this will happen but it the only thing that is useful.

Orb

[e90AW335i]

Some dynos and other information that refute this claim.....(Not SPAM, just information for all)

http://www.n54tech.com/forums/showth...=6611#post6611

[Orb]

Originally Posted by e90AW335i

Some dynos and other information that refute this claim.....(Not SPAM, just information for all)

http://www.n54tech.com/forums/showth...=6611#post6611

Not really, there is a pressure drop for the air box as stated so taking the lid off...well should reduce a restriction as you have more or less deleted it…correct. What I have not mentioned is that the intake track to the air box is a bit of restriction mainly due to its length and the first at bend from the radiator duct. It is a little hard to quantify this by hand calculation and I did iterate this was to get a scale of prerssure drop and nothing in depth. This is what you would call a first step at looking into a problem and obviously as you learn more what you said in the being will change. I don’t plan to take this further but wanted to get a better understanding what is happening because I’m curious just like you.

Also, since the dyno Terry Burger supplied are with out pressure (no idea of flow rate) they are useless from an engineering point of view. BTW, my back ground is not navy based. I have worked as Mechanical Engineer for 16 years on all aspect with Fuel Cell engine design and 11 year of this as CFD/FEA Analysts so I might know a few things that Terry would not.

Orb

[O-cha]

I've always thought the whole "The airbox is a huge restriction and costs about 40hp" crap shiv always spewed was a BS cover story. But I don't think it's not worth any gains at all.

[e90AW335i]

Originally Posted by Orb

BTW, my back ground is not navy based. I have worked as Mechanical Engineer for 16 years on all aspect with Fuel Cell engine design and 11 year of this as CFD/FEA Analysts so I might know a few things that Terry would not.

Orb

I didn't question your background, please don't think I was. I was just supply a link to information that was contrary to what you were stating....