5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
I just recently bought a generic CAI from a eBay vendor "trackracing". I paid approximately $125 for it, shipped to my door.
The quality of the pipe was OK and the filter was a KNN filter. Unfortunately, the vendor included parts I did not need and did not include a part that I did need. The part not included was a vacuum plug, used to seal a hole in the pipe. I went to my local parts store, purchased a $2 rust proof bolt and fitted it through the hole via the provided rubber grommet.
After this, I preceded to install the CAI in parking lot of the parts store. It took a whole 10 minutes.
My immediate impression:
-a sound difference that is noticeable in 1st and 2nd gear at WOT, but thats about it
-little to none power increase
My impression, after driving 500 or so miles:
-sound difference much more noticeable, in all gears at WOT or close to WOT
-maybe 2-3hp gained, something definitely got better (my ego? maybe)
My priorities were to add a bit more bark for my 540i... and this product succeeded in doing so. I just wanted to add more sound and my only power related requirements was that this product should not make my car slower... (and I feel it did not from my "seat of my pants" meter).
If you want the most HP gain, this is not the product for you.
I will post some sound clips and pictures I get a chance...
The only intake I've ever tried that made a noticeable gain in power was an "Iceman" cold air intake I bought for my old '91 Civic Si. I didn't run any computational fluid dynamics flow models or anything, but I AM an engineer, and a visual inspection revealed why it boosted low-end power: the plastic intake tube was tapered, decreasing in diameter from the filter to the throttle body (sort of the opposite of your intake). The gradual decrease in diameter was made possible by a molded two-piece design, where the two tube halves were bonded together and smoothed. Anyhoo, the diameter reduction seen by the intake air on its way thru the tube to the throttle body accelerates the air's speed, giving a little bit of a frequency-specific boost at lower revs, and a little more turbulence entering the intake manifold.
That's my theory anyway. I'd try an intake with that kind of design. Meanwhile, I'll just stick with my whisper-quiet stock sports sedan (sigh)...
__________________ <span style='colorurple'>Eric S.</span>
2006 Honda Odyssey EXL-RES
2006 Honda Accord V6 EX-L Sedan
1999 BMW 540i 6-Speed (Sold to M3UOND on 9/21/06)
1991 Honda Civic Si - Occasional Beater
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