[orlijahwood]

I have a 1990 si, all stock engine. Would a cold air intake benefit me, and if so, is $40 unused a good price??

 

[marine]

Yup...That's a good price IMO. And of course it will improve your engine. Cold air combusts better than warmer air. That helps it make more power.

-= Justin =-

 

[baker_jeff]

You most likely won't notice a huge difference without a header and exhaust as well, but it will help your gas mileage, and you'll HEAR a difference thats for sure! With my CAI I lost torque down low, but gained up high.

 

[Charlie]

you might not notice much of a difference, but it will definately sound better :twisted:

 

[ollie]

What make CAI?
For $40 that sounds like a decent deal.

 

[orlijahwood]

I don't know what make it is. I found it on craigslist

 

[Neo_ART]

most cold air intakes run $100+ so if it is in fact a CAI then $40 is awesome. I've always wondered what the difference between a ram air and a cold air intake was though, because they all looked the same. but the ram air intake is way cheaper, and can usually be found on ebay from $15+ (also is there a big difference in performance between the two?)

 

[bobski]

Cold air combusts better than warmer air.

No actually, warm air combusts better since it helps vaporize the fuel, resulting in a more complete burn. You can get more power out of cold air because it's more dense. Higher density means there's more air and thus oxygen in a given volume. More oxygen means you can burn more fuel, which results in more power. There is a limit though - once intake air temperatures get below about 32°F, you will start to lose power.

I've always wondered what the difference between a ram air and a cold air intake was though, because they all looked the same

A real ram air intake (not the e-bay junk) generally has an air scoop set up so that wind is funneled down the intake, producing a slight positive pressure. The speeds required for a noticable power gain from the ram-air effect are higher than would be reasonable on anything short of a race course.
In ebay terminology, I think cold-air intakes are long enough to reach down into the fender, where ram-air intakes simply pull warm air from the engine bay.