homemade intake manifolds-questions

[1993-Talon-TSI]

i built a custon manifold out of sheet metal (stainless) 240Ci plenium (square) with 5.75 in runners that are not tappered, same size as my inatke ports (ported out a bit so they are slightly larger than stock). The only difference from mine to others like the magnus or BJs is the material type and the tappered runners that mine does not have. My question is i put it in the car and it don't seem to be any better than my stocker! Any of you guys have to tune everything completly different when you put on an aftermarket manifold?
If anyone can offer me some insight or the theory behind High performance intake manifolds on a 4g63T would be of great help.
My setup is a highly tuned 14b, ported head, 3", 255 with 6an, fmic,maft

thanks for the help

 

[kooka]

i put it in the car and it don't seem to be any better than my stocker!

, no kidding.

 

[myblack98gst]

the reason most aftermarket intakes have tapered runners is for velocity of the air..


the one you made is functional because air has to make it to the cylinder somehow.... but I would venture to guess you probably hurt overall performance of the car bay using it.

 

[pneumo]

I've got to give you credit for making an IM on the first try that didn't hurt performance. The reason you didn't make more power is because at the 14b power level the stock manifold isn't a restriction. Once your motor starts pushing large ammounts of air at high rpm, then you'll benefit from a SMIM. Until then keep practicing your fabrication skills.

 

[98gst14b]

Has anyone sucessfully made one? I seem to remember a thread awhile back on instructions for one, j/w because I was planning on building one as opposed to buying one for $500 +

 

[debbie]

Would you have any pictures 1993-Talon-TSi?

 

[Black95TSIawd]

You gained no power because your 14b is WAY out of steam before your stock intake manifold becomes a restriction.


Wholly >>>>. I didn't realize this was a 6 year old thread.

 

[debbie]

You and me both

 

[pneumo]

!