Port Polished Intake Manifold on Ebay.

[RedlineRacer]

I guess you can call it port polished, the guy opened the holes then polished them. It was on Ebay several weeks ago. He said it gave about a 10 hp gain. Is this true? I didn't think it would make that much of a difference if you don't port polish your head too. If it does give a gain, then I am gonna roll over to the junkyard this week and pick one up and start working on it.

[thx247]

Unless he put the motor on a dyno before and after his 10hp gain is purely a guess.

The idea behind porting and polishing is to increase airflow volume and velocity. Porting is where you match the various ports to each other so that there is a smoother transition between manifolds, gaskets, valves. Polishing smoothes the rough edges, casts or welds in the head and manifolds to keep the air moving smoothly. Anything that helps put more air in the combustion chamber is a good thing for power.