[nissantiida]

Can it be done on MR20 for more power

 

[rstolz]

high cost, little gain.

that should be one of the last things done to find power. And honestly it does more to improve response than add raw power.

 

[jswilson1987]

It depends on the shape of the port. The intake and head have to be lined up exactly. So if you do port work on the head you have to port the intake which will be difficult as its plastic. You could maybe clean up .020-.040 in the port before its bigger than the gasket. Now a professional machine shop could weld the bottom of the ports and raise the port so its a straighter shot to the valve. that would be rather expensive in the 2-3000k range ive seen on vw heads were a tube was welded in strait at the valve and then dual webers on it. Insane top end but no torque were talking 200+HP 1.6 for a ministock. You best bet is taking a complete head/intake to a speed shop and seeing what they think

 

[07Versa6MT]

I may go to the wreckers and pick up an MR20 head to dedicate to a port and polish. The ports are pretty well optimized from factory. As was mentioned, the best thing to do is to get a dedicated head for this kind of fooling around, and take it to a place that does this stuff. I'm wondering if bigger valves may be better, QR25 intake valves maybe? Porsche 928 stroker guys use Porsche 968 intake valves (968 used a 3L I4, so 6L is what stock 968 valves could provide for in V8 form).