So why is everyone so anti-CAI?

**NC325iC** · 01-02-2009, 08:26 PM

thats a nice drawing but it says nothing

**smonkbmw** · 01-02-2009, 08:57 PM

ive never seen a dyno on a cai for a m20. ive only heard random bs, nothing conclusive. i ran a open filter on my ETA pre and post chipped and noticed no difference. makes noise and the motor seems to rev up faster, but that doesnt mean power. I put the stock airbox back in with a new filter and it feels more torquey but again, who knows there is no conclusive evidence. just random BS.

if you want to make power in your e30 either build a turbo kit or step to the plate and put a 24 valve in.

**chucko** · 01-02-2009, 09:09 PM

Originally posted by M42Technik

Just swiss cheese the stock airbox like Porsche does...you get the sound and heck maybe a placebo-like effect of going faster.

K&N drop-in filter is something I've been meaning to do.

This what you're talking about?

I saw this mod on the UK forum but I didn't think it was that popular here in the states. It's supposed to help the sound but not much more than that.

**der affe** · 01-02-2009, 09:29 PM

it is LTW that way too. ^^^^^

i purchased a heat shield from KA and put it on my car. i however have a far from stock set up. when i bought the car it came with the filter hanging in the breeze with no means of support and i rigged something temporary that ended up staying for around 2 years until i finally did something about it. it took some customization to get it to work. NONE of which is HIS fault. the FORD MAF and the way the Dbilas intake set up is different from stock so i knew what i was in for. i have since opened up the hole more so i can fit just the cone filter in side of the heat shield, not the MAF and filter.

the end result was that i was able to lean it out 3-4 clicks on the piggy back on the idle setting and 4 on the high side. more power, better gas mileage, still sounds great.

**scottyp** · 01-02-2009, 09:29 PM

when i bought my 325is it had a cone filter with heat shield. makes the exhaust drone more and lost me some low end torque, thats about it. put the stock box back on noticed more torque instantly.

**der affe** · 01-02-2009, 09:33 PM

Originally posted by der affe

it is LTW that way too. ^^^^^

i purchased a heat shield from KA and put it on my car. i however have a far from stock set up. when i bought the car it came with the filter hanging in the breeze with no means of support and i rigged something temporary that ended up staying for around 2 years until i finally did something about it. it took some customization to get it to work. NONE of which is HIS fault. the FORD MAF and the way the Dbilas intake set up is different from stock so i knew what i was in for. i have since opened up the hole more so i can fit just the cone filter in side of the heat shield, not the MAF and filter.

the end result was that i was able to lean it out 3-4 clicks on the piggy back on the idle setting and 4 on the high side. more power, better gas mileage, still sounds great.

my pic didn't work, one more time

**norcalE30** · 01-03-2009, 12:25 PM

a CAI will help a little if you truly are drawing colder, and therefore more dense air into the engine, but not much. CAIs work better with a modified motor that needs more air than the stock setup can provide freely. so if you have headers/chip/throttle body/exhaust you will see bigger gains than with a stock engine. The stock airbox is fine for a stock engine

**Tangent** · 01-03-2009, 12:38 PM

I swiss-cheesed the intake on the 84 GTI I had years ago, but I used about A 1.5" hole saw and drilled fewer holes than the pics above. It didn't do anything for power but it sure did sound mean!

**92 mtechnic cabrio** · 01-03-2009, 04:51 PM

you lose power when you swap the stock airbox out for something else.

it's been proven.

/CAI

**SpecRaceM5** · 01-03-2009, 10:27 PM

Here is why. BMW spends a ton of money on it's engineers who have developed a more true, cold air intake then some filter on a stick. Your stock filter has a box to keep hot air out and picks up fresh air from the front of the car. Hence, cold air intake. By putting a filter on a stick, you lose the heat shielding and you no longer get that fresh air from the front of the car. If you add a heat shield, you are still not getting air from the front of the car like the factory one, and if you are then you have basically built yourself a factory intake. Get it? If you were to fit an M30 air box or something, then you are going to get a larger filter surface and more air flow. If you upgrade your throttle body then you may actually be able to make use of this, but you will need to upgrade your software. Then you will probably need more fuel so that you do not run lean. That means bigger injectors and bigger fuel pump. Are you getting it yet? Just putting a big filter on a stick is not going to get you anything and may hurt your performance. Personally I would stick with the intake that BMW spent the money on. Just my 2 cents. If you want more power, get a chip and a 4.10 lsd. If you still want more, go with FI or a motor swap.

Cheers,

Brian

**SpecRaceM5** · 01-03-2009, 10:32 PM

See that plastic thing the arrow is pointing to. Hot coolant lives right next to your filter. The heat shielding in combination with the coolant tank is hot boxing your air filter.

Another good place to pull air from if you are convinced on the filter on a stick upgrade, is cowl induction. You get a nice fresh air charge on the cowling where your wiper motor sits. Putting the intake there with proper heat shielding will get you a good fresh cool air on your intake.

Attached Files

**JasonC** · 01-03-2009, 10:46 PM

Here's my 2 cents.

I have had both stock and CAI on both of my e30's. I could not tell any difference with either one. Only difference that i could tell was when there was no heat sheild for the cone filter. The car lost alot of power. I put the heatsheild back on, and it ran just like it did with the stock air box. But me being me, i never leave my cars stock for very long. And thus i still have the CAI on my e30 now.

**dandingo** · 01-03-2009, 10:54 PM

I really appreciate all of the comments. This is exactly what I was looking for when I searched the forum previous to this thread. All of the other threads said was to not do it but never included reasoning. there's a lot of good positives and negatives I've learned.

I do have a Mark D chip right now and just bought 19lb. injectors and the Mark D 19lb. chip. If I do anymore upgrades, I'll consider it but for now I think I'll save my cash.

This should also be a good thread for any other new guys looking to do CAIs as well.