port and polish exhaust manifold and intake manifold

[hungryjoseph]

any here port and polish their exhaust and intake manifold? any power gains from the pnp'ed exhaust manifold? any gains with the intake? what kind am i looking at

[IanS]

most people do the intake P&P and port match the intake mani when they P&P the head, doing just the Mani wouldnt really make much of a differance.

[garagelu]

Its pretty much impossible to port and polish intake and exhaust manifolds because the runners are so long. There is no way to get a tool in there. You could extrude hone the manifolds but the cost is going to be expensive. You are better off buying a greddy manifold and a tubular manifold. Go with the proven way.

[hungryjoseph]

so it's impossible to pnp the exhaust manifold? if not, then just a pnp on exhaust manifold wont give me any gains? no spool up gains? lower end?

[garagelu]

so it's impossible to pnp the exhaust manifold? if not, then just a pnp on exhaust manifold wont give me any gains? no spool up gains? lower end?

well what kind of tool would you use to get into those runners. Its pretty much too difficult or impossible. You will see more gains smoothing out the ports in the head.

And you cant port and polish an exhaust manifold. Again the runners are too long. You cant get any tool to do it. Just get a tubular manifold.

[Emperor_Tha]

if you got the tool such as the metal grinding and sand paper wheel. then go for it. just try to get as much polish as possible. probably wont see much of a gain. but it will flow better then before.

[Hijacker]

garagelu is right. it's next to impossible to get a grinding tool into the hidden corners of the manifolds. extrude honing is really the only good viable option.

You'll see more benefit from extrude honing the exhaust manifold than you will the intake mani, though. Relieving backpressure of the exhaust system will give more performance gains than opening up the intake path

[garagelu]

and even if you could get a tool in a intake manifold to port and polish it, its not worth the time to do it. Do you know how much labor would go into that? And the result would be like a couple hp maybe? And to fully see the result, you would need to bench flow it. You cant see the gain on a dyno...it will be too minimal.

Save your money and buy a greddy manifold. The cost of extruding a manifold is pretty close to the cost of a greddy manifold. Plus it looks better.

Relieving backpressure of the exhaust system will give more performance gains than opening up the intake path

And this is very true....you dont want the intake path to be completely smooth. You want your intake port to be a little rough so the air and fuel can mix. And there is swirl and other stuff to consider.