Port and polish - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Drift Style S14 · 01-28-2002, 09:00 PM

well?

sspikey · 01-28-2002, 09:01 PM

depends on what type of car. on turbo cars it will eliminate some lag if done right. on n/a cars i think its more of a supporting mod for other things.

wasabi · 01-29-2002, 12:22 AM

works extremely well on turbo cars since they depend on airflow more. i've seen some honda's have it done, but results varied.

Cheater240SX · 01-29-2002, 07:00 AM

I think a port and polish job on the exhaust side would help tremendously.  On NA engines, people worry about making the tport too big, losing gas velocity and losing torque.  On a turbo car, you lose the effect of exhaust gas momentum created by small diameter, long runners.  Go big and shiny.  

Also, KA heads are cheap enough to play with on your own.  Get a die grinder and some polishing wheels and try it.  Run into a coolant passage?  Start over with a new head and a lesson learned.

WhiteS13 · 01-29-2002, 08:51 AM

How much does a used KA24DE head usually go for?
You got me thinking now. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

Intake ports for NA applications could also benefit a bit more if your don't smoothen the walls too much.  This reduces turbulance.  Exhaust ports, you can go as shiney as you want.

On my last car, I ported the head myself (because of blown headgasket) and noticed a nice increase of torque in my small Honda motor.  The stock pieces aren't too bad, and the ports are relatively clean.  I just removed the casting imperfections and smoothened the walls a bit.  Results were satisfactory.

nos240 · 01-29-2002, 08:46 PM

so, does ne one ever done this on their 240? how much gain in horsepower and torque are expected? i've heard ppl said that rough idle may expected after porting and polishing.

alchemist · 01-30-2002, 12:18 PM

on a stock  or NA engine the port/polish wont really so much in the way of HP/TQ increases.  On a turbo it will help the head breathe easier.  Remember that Nissan and Honda already use very effiecent head designs, unlike older US cars.....american pushrod V8's benefit greatly because of their ineffiecent design from the factory,  Nissan engines already have better heads, so it wont really do much unless turbo's and even then not a huge difference.

Cheater240SX · 01-31-2002, 03:16 PM

alchemist---Got any data to back that claim up that port and polish won't help much?  I think that it would definitely help, how much?  I don't know.  

GUDE offers a ported/polished head with their cams that is supposed to give a significant power increase.  I think it was about $1200............

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01-28-2002, 09:00 PM	#1
Drift Style S14 Zilvia Addict Join Date: Sep 2001 Location: Pinole, California Age: 38 Posts: 602 Trader Rating: (0) Feedback Score: 0 reviews	well?

01-28-2002, 09:01 PM	#2
sspikey Zilvia Junkie Join Date: Dec 2001 Posts: 394 Trader Rating: (0) Feedback Score: 0 reviews	depends on what type of car. on turbo cars it will eliminate some lag if done right. on n/a cars i think its more of a supporting mod for other things.

01-29-2002, 12:22 AM	#3
wasabi Join Date: Jan 2002 Posts: 28 Trader Rating: (0) Feedback Score: 0 reviews	works extremely well on turbo cars since they depend on airflow more. i've seen some honda's have it done, but results varied.

01-29-2002, 07:00 AM	#4
Cheater240SX Join Date: Jan 2002 Posts: 40 Trader Rating: (0) Feedback Score: 0 reviews	I think a port and polish job on the exhaust side would help tremendously.  On NA engines, people worry about making the tport too big, losing gas velocity and losing torque.  On a turbo car, you lose the effect of exhaust gas momentum created by small diameter, long runners.  Go big and shiny.   Also, KA heads are cheap enough to play with on your own.  Get a die grinder and some polishing wheels and try it.  Run into a coolant passage?  Start over with a new head and a lesson learned.

01-29-2002, 08:51 AM	#5
WhiteS13 Leaky Injector Join Date: Jan 2002 Posts: 73 Trader Rating: (0) Feedback Score: 0 reviews	How much does a used KA24DE head usually go for? You got me thinking now. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'> Intake ports for NA applications could also benefit a bit more if your don't smoothen the walls too much.  This reduces turbulance.  Exhaust ports, you can go as shiney as you want. On my last car, I ported the head myself (because of blown headgasket) and noticed a nice increase of torque in my small Honda motor.  The stock pieces aren't too bad, and the ports are relatively clean.  I just removed the casting imperfections and smoothened the walls a bit.  Results were satisfactory.

01-29-2002, 08:46 PM	#6
nos240 Leaky Injector Join Date: Jan 2002 Posts: 69 Trader Rating: (0) Feedback Score: 0 reviews	so, does ne one ever done this on their 240? how much gain in horsepower and torque are expected? i've heard ppl said that rough idle may expected after porting and polishing.

01-30-2002, 12:18 PM	#7
alchemist Zilvia Member Join Date: Oct 2001 Posts: 192 Trader Rating: (0) Feedback Score: 0 reviews	on a stock  or NA engine the port/polish wont really so much in the way of HP/TQ increases.  On a turbo it will help the head breathe easier.  Remember that Nissan and Honda already use very effiecent head designs, unlike older US cars.....american pushrod V8's benefit greatly because of their ineffiecent design from the factory,  Nissan engines already have better heads, so it wont really do much unless turbo's and even then not a huge difference.

01-31-2002, 03:16 PM	#8
Cheater240SX Join Date: Jan 2002 Posts: 40 Trader Rating: (0) Feedback Score: 0 reviews	alchemist---Got any data to back that claim up that port and polish won't help much?  I think that it would definitely help, how much?  I don't know.   GUDE offers a ported/polished head with their cams that is supposed to give a significant power increase.  I think it was about $1200............