Opinions on Head Port and Polish?

[96240sxSE]

Anybody have a ported and polished head? Looking for a little bit of info, since I'm gonna have a chance to port and polish at school, and its free. Wondering if it's even worth the effort, and what type of gains I could expect if I did do it. Any info would be appreciated. This is a (temporarily) stock KA. By the time I get to that class, I should have I/H/E and possibly some new cams.

[RBS14]

Do it! KA heads are quite restrictive from what i hear. Even if they aren't, you will still notice hp gains. Just remember when porting and polishing, your intake and exhaust manifold runners need to be port matched. i.e. the same size. Since you are not experienced in headwork, i would recommend just taking out casting marks then polishing, don't do too much porting. What you think would help with air/gas flow doesn't always help. Make sure not to hit your valve guides too, you do not want to replace those. Oterwise have fun and learn a lot!

[kandyflip445]

From what I've heard you don't port match the exhaust. Something to do with reversion?

[96240sxSE]

Hmm, thanks for the info so far. I have 6 months to think about it, I may be dropping new cams in at the same time, and don't want to screw anything up. Anybody else have any info on doing head work?

By the way, a little OT, but if anybody wants to go to an automotive tech school, check out WyoTech. The scenery sucks, but the schooling is great. I'm taking Chassis Fabrication/High Performance Engines after my automotive core.

[Roly]

There are quite a few stock head KA's running 12's and 13's. I suggest a mild p&p, with stock 91 KA cams for best results.

[AceInHole]

Originally posted by Roly
There are quite a few stock head KA's running 12's and 13's. I suggest a mild p&p, with stock 91 KA cams for best results.

how about Duy's old 10sec car with a stock head?

[AceInHole]

Originally posted by kandyflip445
From what I've heard you don't port match the exhaust. Something to do with reversion?

Yeah, the exhaust side generally isn't port matched unless it's going to a smaller port, i.e. large head port opening to a small manifold port opening. This is so when the exhaust gas travels back between pulses, the mis-matched port acts as a "wall", helping keep exhaust gases going out instead of in.


Edited in:
Anyways, if you're taking a class about it I'm sure you'll learn in there.... but the quick run through:

intake ports: should be rough to the touch (helps atomized gas to mix with the air flowing in). Casting peices in the bowl area above the valve are where you'll have to do the most work.
one wall done:

exhaust ports: should be mirror smooth to help keep carbon deposits from sticking. I forgot where but there's a decent hump in the port that can be flattened out. I recall it being somewhere behind the divider.


When I ported my old head, I folloed this guide: http://www.sa-motorsports.com/diyport.htm

Good luck!

[96240sxSE]

Thanks for the info guys, gonna have to think about it, I don't want to screw up my head, cause I sure don't have the money to replace it.

How hard is it on a scale of 1-10? 1 being an oil change, 10 being a full rebuild.