So why is everyone so anti-CAI?

[stevofthahill]

I have a CAI with a proper heatshield, simply because i got it for free! I think it sounds pretty cool, and it does seem to rev more freely. But this is also paired with chip/exhaust.

[kamotors]

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.

fixed?

[tjts1]

that's about it.

K&n drop in filter ftw.

[SamE30e]

They sound nice - that's something!!!

That's about it.

K&N drop in filter ftw.

[kamotors]

with a proper CAI you can get colder air than the OEM setup. I'm looking into fitting a bigger air box on an e30 as we speak. possible one that holds a cone filter in it.

[Jesse30]

i wub brian, well put.

[M42Technik]

I saw a guy from some foreign country make an amazing CAI for an M42, I want to replicate it...I'll find the picture soon.

[tjts1]

So why is everyone so anti-CAI?

Because its the trendy opinion and everyone wants to fit in.

Well, at least for the M42, the stock airbox is plenty big enough and offers very good filtration. The only real bottleneck is the intake tube behind the headlights. Replace that hose with a 3" diameter pipe and that is as good as you will get without a tuned resonance intake. Ghetto, yes, but it really is the best option. I'm not sure how different the M20 is in that respect, but you won't see much of a gain from a CAI.

+1
22# injectors + CAI to stock airbox = win.

If you didn't get any results from a CAI, it just means you're doing it wrong. All CAIs are not created equal.

[dandingo]

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.

[JasonC]

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.

[SpecRaceM5]

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.

[SpecRaceM5]

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

[92 mtechnic cabrio]

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

it's been proven.

/CAI

[Tangent]

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!

[norcalE30]

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