someone care to explain "port / poilshed heads"? thanks

 

Here's a link that explains it in some detail. The short version is you remove some material from the cylinder head and polish the metal so it flows better.

 

Cylinders heads on production cars are cast aluminum (iron in some cases). This leaves a lot of rough material in the air/combustion passages in the head. This rough material slows down and makes the air entering the combustion chamber turbulent.

When you "port" the head, you are opening up the passage ways to make them larger, or to remove material to create a better path for air to enter.

"polishing" is just that, it's removing the rough finish to leave a very smooth, unrestrictive surface for the air to move through.

It is NOT something a person should do by themselves, as it's very difficult to do a consistant job (meaning, if you do one cylinder great, it's hard to do them all identically the same, and your performance will suffer). It's also very easy to screw up.

Since engines are basically an intricate air pump, the more air you can get in and get out, as smooth as possible, the more power the engine can make.

 

thanks for the info and the link, what kind of results are noticeably gained from this?

 

It depends on how restrictive the stock head is really. Some factory heads flow very well. Others are horrible.

On average, 8-10 horsepower at the wheels on a 4 cylinder. If you have aftermarket cams, then that increase from head porting could go up. If you install larger/lighter valves that changes things too.

 

A word of caution, let a pro do it, and not just some shade tree mechanic with a die grinder. Find a reputable shop with a flow bench and experiance in your area. Otherwise you can lose HP and/or ruin an expensive head.
Also consider looking into extrude honing. http://www.extrudehone.com/ as an alternative to port/polish.

 

The amount of power depends entirely on the motor in question. A Honda motor you typically see little to no gain with stock valve train. On LS1 with a cam you can pick up over a 100. The TC has a very restrictive head as it was never made for high rpms or high performance. With stock valves this head flowed 38% more on our super flow flow bench. You can expect a solid 20whp on the TC with a stage 1 head.

 

hey zpi dont you guy offer a head package with port polish? if so can you pm me how much and how do i set that up.