CAI..pipe diameter ???


15 Year Member
Feb 16, 2001
Anyone care to add there thoughts???

Have to make a CAI for the GT40 upper I added and finding one is a pain So I'm just gonna make one....I'm curious on diameter for the pipe...Keeping velocity in mind I was thinking of a tapered set-up?? I'm leaving the maf as it is in the fender and pretty much a straight shot from the TB..

Pro77 is 4" dia.....Accu75 is 3"...approx 2' inbetween.....My thinking was running 4" tube for approx 10" out of the MAF....then a 4"-3" reducer....and 3" all the way to the TB...
Where would you place the IAC....end of the 4" or few inches up into the 3" for the most accurate value??
My thinking is that 4" tubing all the way is prolly to much dia for my motor?

Also....adding the much would you think this is gonna mess with the AFR??..My last dyno showed the AFR right on the money for the entire pull with the stock 19s/Fox65....So this alone would possibly lean it out more??

I aslo have some 24s laying around...Now this upper feels like it pulls easier/quicker to redline than the 93 Cobra I had before, and since its off I'm thinking this is the perfect time to add the 24s as maybe between the TB/24 upgrade I can scam a few more ponies out of it??...Any thoughts on any gain from adding the 2 parts??....
By adding the 24s I have to doing either a SC or get a tweecer...Not really sure on which way to go there just yet...

The SS tubing/reducers is coming for here and I'm gonna weld/polish the entire set-up....

Will go a 45 out of the TB then straight shot to the MAF...
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I bought a 27" monitor to compensate for my lack o
Apr 29, 2004
Medicine Hat, AB
Hey Rio, sorry to be off topic, but where'd you get those wire looms? They look good and I want to make my wires look a bit better

By the way, Engine looks mint! Good luck with the CAI


Advanced Member
Sep 28, 2003
Indianapolis, IN
Yea i think i'd just do a straight 3.5"....besides....are we talking about differences that could even be recognized by a dyno? Let alone us driving? :shrug: Keep it simple i say.

Im gonna be making one so be sure to show us your finished product.

And could you(or anyone else) help me out with something....where does the vaccum line that is connected to the purge valve go to? Its a vaccum line on the passenger side...the valve is T'd into the line and the line continues into the passenger fender. I forgot where this line connects on the engine.


15 Year Member
Nov 29, 1999
Boca Raton, Florida
I cheated and just bought a fender kit off Ebay for $32 and used the 3 inch pipe with red rubber boots.

I'll change it down the road. Just can't justify the AFM pipe for $232 right now.



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15 Year Member
Feb 16, 2001
3.5 would be better but I can't seem to locate that diameter, the link I added is kinda one stop shopping....I figured a happy medium would be to taper it....I don't mind the time involved as the car's still stored anyway and not coming out for awhile yet...

I scanned Ebay myself, but your filters in the bay and that works for you. I had problems with mine in the bay with surging/hot start issues...I dont want to run more than 2 couplers this time either...TB/MAF only..I looked at those powerpipes and chit too...screw that...:D way to much ching...I was playing with making one myself but I was going for the straight shot thing...Just shooting for something different this time...
Still open to any ideas though....:nice:

Tee into the brake booster line if you dont have an available port...thats what I feed mine from..

Performance Distributors for the looms...They're for Lives wires though...Like 12mm or so, perty could figure something out though as regular wire are to skinny for em...The looms split open (Allen screw in the middle) to fit over the wires then screw em back together...


Mustang Master
Apr 6, 2003
DFW Texas
I noticed the inside diameter of my ProM 80 is just about the same size as the inside diameter of a section of 3 inch pvc.

I do not believe the typical 302 na street combo you find on these boards needs a 4 inch pipe.

I believe the main reason most go for that big pipe is they just follow the power pipe thing from AFM.

Now if you are forced, then a larger pipe is a different story.

Just my .02



Active Member
Apr 11, 2003
on the looms, i just bought a set like that at summit...... do a search for them.. and they are for 9mm taylors.

Andy, i could see doing the taper.....4" to 3" if possible i would try and find the longest reducer that they sell less of a drastic change