reduced mileage with CAI?

Anybody know how installing a CAI affects mileage? I thought I'd read on RSX and Honda boards that they actually improve mileage. I just read on one, however, that some guy with a Civic says it cost him some mpg.

Also, what about emissions tests? Will a CAI cause problems there?

Also, what's the best CAI for a Type S? Injen? or AEM? or what?

Thanks.

Your mileage shouldn't change. You're just changing the air/fuel ratio by allowing more air into the pistons making the car run a little leaner. Acuras/Hondas tend to run rich - meaning there's a lot more fuel in the mix than air- which makes the CAI or even SRI optimal. Honda does this because engines tend to run longer when a rich mixture is used. The CAI is better than an SRI since the CAI is usually located where cold air is brought through the filter. Colder air means that the oxygen molecules are closer together giving you more oxygen per volume and, therefore, more power when the fuel explodes.

The only way to worsen your mileage is to increase the amount of fuel in the mixture. This usually is done for turbocharging/supercharging and is done by placing larger fuel injectors into your car. You can also adjust the A/F mixture by using some computer mods like Hondata.

I don't know which CAI is best but you should take a look at clubrsx. They have a bunch of hp/torque curves for pre and post installations of CAI's.

Thanks a bunch. I think I read on the Club RSX board that Injen was the way to go. I didn't know that there was a listing of hp/torque curves over there. I'l check it out.
Have you ever heard about anyone having a problem passing emissions test with a CAI? Again, I picked that up on some board, but not sure if they knew what they were talking about. From what you say, it doesn't sound like it should be any problemn at all.
Thanks a bunch.
COmmissioner

No, it shouldn't be a problem with emissions. For newer cars the emissions testing sites take their OBD tool and plug it into your car and pass or fail based on any errors you have on the computer.

An SRI or CAI should not create any error codes. A turbo/scharger might, but the Hondata computer mod can take care of any error codes before you take it in for testing, I believe.