RPi Ram Air or AFE CAI
Thread Starter
Contributors
Joined: Sep 2009
Posts: 315
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From: Atlanta, Ga. USA
My Ride: '07 530iSport PackageLuxury Packagemore to come
Being new to this model I have a lot to learn so I'm seeking the advice of you sage members.
On my E36 the CAI, cold air intake, was the way to go and I never heard of this ram air thingy. I understand the principle of the ram air but see little low end advantage. The CAI starts helping immediately. It also seems to me that the engine can only use so much air without making things too lean. Wouldn't you need to increase the size of all the air plumbing and remap the A/F ratio somehow to realize any gain? The CAI simply isolates the air filter from the heat of the engine compartment allowing a cooler and more efficient(?) burn. No worries of running lean either.
So I guess both would probably be the best, but again I think about the A/F ratio.
More air... Ram Air
Cooler air....CAI
Better exhaust... get that bad stuff out
Seems like the best set up.
Ideas?
On my E36 the CAI, cold air intake, was the way to go and I never heard of this ram air thingy. I understand the principle of the ram air but see little low end advantage. The CAI starts helping immediately. It also seems to me that the engine can only use so much air without making things too lean. Wouldn't you need to increase the size of all the air plumbing and remap the A/F ratio somehow to realize any gain? The CAI simply isolates the air filter from the heat of the engine compartment allowing a cooler and more efficient(?) burn. No worries of running lean either.
So I guess both would probably be the best, but again I think about the A/F ratio.
More air... Ram Air
Cooler air....CAI
Better exhaust... get that bad stuff out
Seems like the best set up.
Ideas?
Senior Members
Joined: Aug 2008
Posts: 838
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From: Davie, FL
Originally Posted by SBrown712' post='1028226' date='Oct 9 2009, 12:16 AM
Being new to this model I have a lot to learn so I'm seeking the advice of you sage members.
On my E36 the CAI, cold air intake, was the way to go and I never heard of this ram air thingy. I understand the principle of the ram air but see little low end advantage. The CAI starts helping immediately. It also seems to me that the engine can only use so much air without making things too lean. Wouldn't you need to increase the size of all the air plumbing and remap the A/F ratio somehow to realize any gain? The CAI simply isolates the air filter from the heat of the engine compartment allowing a cooler and more efficient(?) burn. No worries of running lean either.
So I guess both would probably be the best, but again I think about the A/F ratio.
More air... Ram Air
Cooler air....CAI
Better exhaust... get that bad stuff out
Seems like the best set up.
Ideas?
On my E36 the CAI, cold air intake, was the way to go and I never heard of this ram air thingy. I understand the principle of the ram air but see little low end advantage. The CAI starts helping immediately. It also seems to me that the engine can only use so much air without making things too lean. Wouldn't you need to increase the size of all the air plumbing and remap the A/F ratio somehow to realize any gain? The CAI simply isolates the air filter from the heat of the engine compartment allowing a cooler and more efficient(?) burn. No worries of running lean either.
So I guess both would probably be the best, but again I think about the A/F ratio.
More air... Ram Air
Cooler air....CAI
Better exhaust... get that bad stuff out
Seems like the best set up.
Ideas?
Short version:
Stay away from the AFI CAI, it causes you to LOSE power.
RPi Is the way to go. They're loved on these forums.
Long version:
Search.
Welcome to the forums.
Contributors
Joined: Aug 2008
Posts: 9,986
Likes: 1
From: Zoo York
My Ride: Alpine White 2006 530Xi (SLD)
I've done a little research on this 
AFE nets a loss of HP at the wheel - dyno-tested; you can find data on this forum or elsewhere.
RPI scoop+BMC filter net a small gain (also dyno-proven).
It was simple for me to decide. That said, I'm also planning to heat-wrap the intake plumbing one of these days.
Gains? Real life, the gains are modest. Don't expect your car to become a whole new beast - but I think you know what to expect. It does pull harder and it does get up to speed quicker now - no doubt about that
Oh yeah, PS:
Welcome to the forums!
AFE nets a loss of HP at the wheel - dyno-tested; you can find data on this forum or elsewhere.
RPI scoop+BMC filter net a small gain (also dyno-proven).
It was simple for me to decide. That said, I'm also planning to heat-wrap the intake plumbing one of these days.
Gains? Real life, the gains are modest. Don't expect your car to become a whole new beast - but I think you know what to expect. It does pull harder and it does get up to speed quicker now - no doubt about that
Oh yeah, PS:
Welcome to the forums!
Contributors
Joined: Feb 2008
Posts: 4,074
Likes: 0
From: Fullerton, CA
The afe or similar open air intakes loose power due to heat soak. The engine produces heat temps upwards of 200 degrees. When you have an open intake it sucks in the hot air created by the engine. If you run tge vehicle hard over and over tge car will loose power. When using the stock box it dissipates the heat efficiently. The reason why all high performance production vehicles like Porsche, Ferrari, lamborghini, etc all come with a plastic air box.
The race precision ram air scoops utilize the stock box whille adding 9-12 whp. When the RPI ram air scoops are used in addition with the drop in filter, the vehicle can be run hard without power loss.
Do a search
The race precision ram air scoops utilize the stock box whille adding 9-12 whp. When the RPI ram air scoops are used in addition with the drop in filter, the vehicle can be run hard without power loss.
Do a search
Contributors
Joined: Aug 2008
Posts: 9,986
Likes: 1
From: Zoo York
My Ride: Alpine White 2006 530Xi (SLD)
Originally Posted by dbae1978' post='1028268' date='Oct 9 2009, 01:31 AM
The afe or similar open air intakes loose power due to heat soak. The engine produces heat temps upwards of 200 degrees. When you have an open intake it sucks in the hot air created by the engine. If you run tge vehicle hard over and over tge car will loose power. When using the stock box it dissipates the heat efficiently. The reason why all high performance production vehicles like Porsche, Ferrari, lamborghini, etc all come with a plastic air box.
The race precision ram air scoops utilize the stock box whille adding 9-12 whp. When the RPI ram air scoops are used in addition with the drop in filter, the vehicle can be run hard without power loss.
Do a search
The race precision ram air scoops utilize the stock box whille adding 9-12 whp. When the RPI ram air scoops are used in addition with the drop in filter, the vehicle can be run hard without power loss.
Do a search
Former Vendor
Joined: Oct 2006
Posts: 19,460
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From: Anaheim, CA
My Ride: F13 M6
Originally Posted by v_therussian' post='1028270' date='Oct 8 2009, 10:33 PM
BTW is that charcoal filter delete mod officially beneficial?
Contributors
Joined: Mar 2009
Posts: 10,301
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From: New York, New York
My Ride: See my signature
The AFE "hot" air intake is, without question, the most reviled and critized "performance" mod on this board. A number of respected members bought it and installed it -- and then removed it after reporting a significant loss in power. If you want to go slow, go AFE. If you want to go faster, go RPI. It's that simple.
