I've decided to buy an s5 jspec and rebuild it on my own as my t2 has 122k miles on original engine.

Which directions can I port it out to and still have an alright chance of passing emissions w/ a cat, airpump. I'll resort to the typical tricks of



For intake ports, I was thinking pretty mild primary and a little more for secondary, sort of like a "baby ito port".

I think that I'm going to focus on efficiency of smoothing out the edges of the port and have velocity work on my side rather than ridiculous port timing.



But on to the exhaust

Any suggestions on how far I can port in each direction without really hurting emissions?

I am also aiming for low/mid end and torque, as it is my daily driver.

For top end I'll just let the secondary intake port and turbo do the work for my topend.



I have the same sort of visions all around. Mild intake ports w/ larger secondaries and some good shaping to help w/ efficiency more than huge timing.

Then port match/clean up the intake manifolds and do a little to the throttlebody, but I plan to keep the double throttles functional.

And for exhaust I have no idea https://www.nopistons.com/forums/pub...#>/biggrin.png I have only seen that keeping the top of the exh port close to stock, and porting down and out is better for low/mid range and doesnt increase overlap which I would assume would help from killing emissions



And thank god for this forum. By far the winner for porting/engine building information, especially with ito so active on this board.



Thanks,

Ben Martin

when i built mine i moved the opening down like 1mm and then matched the sleeve. the upper i also matched the sleeve, and rounded it off. on the intakes i removed the casting flash from the runners. it seems to pull a little harder than the average bear, and since i didnt change the port timing it should still pass

sounds good, maybe port a mm more down and 1mm out to the sides.

vroooooooooooooooooooom

loowend baby.

anyone, anyone, beuller?