Another dumb Q...What is port & polish?

[crazie.eddie]

I've heard this a few times, but I was wondering what port & polish means regarding mech chat? I'm assuming that polish is not keeping the engine nice and shiney.

[hoopdiewagon]

widening and making a smooth part for air to flow is basically it. The more air you can get in, the more power you can make. Same works on the reverse side...widen your exhaust and get more power (its all about air flow- in and out). Some port thier intake manifold, some do the throttle body, others go further and do the head as well.

[CREWZIN]

quote:Originally posted by hoopdiewagon

widening and making a smooth part for air to flow is basically it.

The smoother things are for the flowing of air, the faster it can travel. The K&N filers are supposed to do the same thing for the air flow thru the fitering part of the intake.

[purple04]

port & polish started very early. It's a science and a bit of an art. The area at the intake and exhaust valve are the smallest (most restrictive) areas that flow air in and out of the motor. Anything that helps airflow through this area can increase power. The procedure is intended to tune the motor to work the best possible at the RPM range selected. Just like any other mod, the intended use must be matched. You have the physical limits of the parts, the need to equilize the work and the cost VS benefit. As an example (w/pics) look at this...http://www.moparts.com/Tech/Archive/motor/31.html. I'm sure there are other discussions out there.

[littleblueGT]

Don't attempt to port and polish if you don't know what you are doing as you can easily ruin your head.People use to think the bigger the better, but found unless you balance between intake and exhaust performance can actually go down.Some would remove too much material including around valve guides and valve seats causing premature wear and engine failure.In some cases opening the ports was good , but dyno test showed lower performance with polishing the ports.In some cases the rough surfaces cause a "boundry layer" effect and the air actually will flow better.A flow bench is the best way to test. This is not something for a novice to jump into! That is unless you have a lot of money and don't really care.

[quicksilverdon]

Earlier intake and exhaust mahifolds and heads were cast iron using sand molds and were left rough. Grinding and polishing off the rough surfaces increases air flow. That's the polishing. Porting did the same to intake and exhaust ports, also widening them.

[crazie.eddie]

Thanks everyone.