Celica Forums General Discussion Exterior Intake Length?

Does anybody know how the length of your intake(not the manifold runners, but the part after the throttle-body) affects the performance of the car? And what is the avg. length of a short-ram vs. CAI? Any help would be appreciated. Thanks.

[ 02-03-2003, 09:34 PM: Message edited by: MyCeli8U ]

When myself and a shop were building my CAI for my Contour, we experimented with length. This guy had done the same on a Civic and saw great gains. It involved quite a bit of math utilizing bore, stroke, TB inner diameter, etc.; but it was WELL worth it.

As an example: Most stock Zetecs w/ 5-spd. dyno at about 103 FWHP. I had chopped my stock intake up before meeting him, so I never had a true baseline. With my chopped up intake, I put down 111 FWHP. With the final version of the CAI, I put down 122 FWHP. With the Zetec, the optimum length was a little over 30 inches.

The length of the pipe didn't have so much an effect on peak HP, but more on power under the curve (usable power throughout the rev range). By varying the length, we were able to come up with a happier power band than if we hadn't dyno-tuned it.

Hope this helps some.

So you kinda fiddled with it and then used a dyno to see what length/bore gave you the best results? I don't have access to a dyno so do you know any of the mathematics involved? Just some of the basic principles would get me started. I have good understanding of math, thanks so much for the reply !

Well, I didn't know how in-depth it was gonna be. When he started scribbling on the whiteboard at the shop I had to make sure I was in the right place

I don't remember much about the math involved, but the diameter remained the same as the TB. Since this is a slightly smaller engine, there would be difference, but how much different I don't know.

Maybe I can get the wife to let me borrow the Celica and take it down one day to see what we can come up with.

[ 02-04-2003, 03:20 PM: Message edited by: D Davis ]

That's cool, , Thanks a lot for your help man. I'll figure it out. I know i can't afford to buy a CAI so i'm gonna put my head and hands to use, and make my own, better than theirs!... maybe.

BTW, when I mentioned there'd be a difference between a CAI for the Celica and one for the Zetec, I mean optimum length. I don't see any reason you'd want to adjust the inner diameter to be different from the largest inner diameter of the TB.