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just bought a 10.5 housing for my evo 8 and i was courious if it was safe to take it to any machine shop to get it ported and polished. is this a universal thing or does the shop need to know the tolerances of the housing? is this worth doing first of all? i was also thinking of doing the stock manifold.

 

Buschur Racing did mine very good job.

 

definately do both, exh man & hotside.....get a decent o2 housing while you have it all apart & you'll pick up some decent power!!

 

Most of the power to be had by porting the exhaust bits of your Evo, is in the porting of the stock, cast iron, exhaust manifold(approx. 8 WHP). An EBAY or similar O2 housing(10-15 WHP), which requires no porting, as WOT said, is a nice addition while you've got everything else off anyway.

You could send the the 10.5 turbine housing and the exhaust manifold in to either Buschur, PPI, or WOT for porting and, if you so wish, thermal coating. Sending it to anyone of the above qualified Evo-experienced machinists is preferable than farming it out to a general automotive machine shop with no Evo experience.

The 10.5 turbine housing gives you about 15 WHP without the need for porting. No one, to my knowledge, has dynoed what, if any, horsepower gains are derived from porting the 10.5 housing per se. What specific areas can actually be ported on the turbine housing that could increase power anyway? Yes, you can gasket match the turbine housing inlet to the exhaust manifold outlet. Maybe this is worth a tiny bit and should help initial spoolup. Porting the wastegate bypass port, if done properly. should improve bleed flow out through the WG.

All I'm getting at is that porting the turbine housing on a 16G, in and of itself, hasn't been proven to increase horsepower. At least it hasn't yet been quantified, AFAIK.