CAI Question

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fhadso
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CAI Question

Post by fhadso » Tue Jun 04, 2013 6:14 pm

So I've gone through two different CAIs. The first one I had was (roughly) 2.25" piping, two pipes, one between the manifold and TB, and one that bent down into the fender well.

The one I have now has two 3" diameter pipes, one coming from the TB into the resonator hole, and then one going to the filter from there. This one is wedged in because it A) didn't come with a shorter IM/TB pipe, and/or B) it was designed for the stock accordion tube that allows for more or less length and travel. It is so wedged in there, I had to modify the coupler several times, and put a piece of vacuum hose on the fender to keep the pipe from rubbing away.

I almost feel like the 3" piping allows for more air flow, even though the throttle body is bottlenecking air flow with it's 2.25" diameter. I noticed a slightly better throttle response and overall pull with the 3" piping, but this might just be a placebo effect.

My question is: Am I actually getting more power due to the increase in diameter? Is 3" too much? Would 2.75" work just as well? Or is there any difference?

I'm trying to find a better system because the intake I have now has the dreaded foghorn effect, and it makes me sound like I have a bad wheel bearing or something. Not only that, but there is no way that the way I have it jammed in there is good for the piping.

occasional demons
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Post by occasional demons » Tue Jun 04, 2013 10:53 pm

The only time the 3" might make a difference is at WOT.

Otherwise, at part throttle, you are flowing far less than even what the 2.25" is capable of.

FWIW, the TB is only a shade over 2", minus the thickness of the throttle shaft. 52mm = 2.047" So in reality, the area of the TB at WOT is less than a 2" opening. ;)
Bill
Olha Koba, a psychologist in Kyiv, said that “anger and hate in this situation is a normal reaction and important to validate.” But it is important to channel it into something useful, she said, such as making incendiary bombs out of empty bottles.
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fhadso
n00b
Posts: 22
Joined: Tue Jul 24, 2012 2:26 am

Post by fhadso » Wed Jun 05, 2013 4:16 pm

Ah. Noted. I knew the TB was around 2", and when I measured my last CAI, it wasn't quite 2.25", and was very restrictive and bogged down very easily.

Too bad they don't make a 55mm TB that doesn't require mods to function correctly. I would get the MPx 60mm, but I have an '05.

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