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

rufrydrsc2 · 07-10-2003, 09:34 AM

I had my motor rebuilt top and bottom end, bored, ported and polished. I didn't get a stock dyno to compare it to, but I was just curious how much hp gain I could probably expect from Porting and Polishing. I can definately feel the difference after the rebuild, plus the fact that I had the shop gut my transmission and build me a new one completely from scratch. I have an automatic but it would bark my old tires shifting from first to second as they were just radials. It won't bark my Toyo Proxies, but they are pretty sticky. I know what yall are all saying in your heads, a damn automatic, but it's a good transmission. It has a very instant on feel to it. It hits hard into each gear nomatter if you're driving easy or hard (definately from the build). I'm going to go turbo at around 15psi hopefully before this winter and was just wondering about what I am getting from each modification before then. I don't see alot of people that have gotten porting and polishing done on here, or at least they don't say so in their mods. Is it a common mod on 240's? I am really new to 240's as I am a mustang guy, but my wife owned a '91 240 hatchback when we got married and has since given me permission to (quote "do what you want to it"). Future mods before the turbo are KYB AGX shocks, Eibach pro-kits (which I'm carrying around in the trunk right now), MSDS header, and an Apex-i N1 dual exhaust.

Bill Roberts · 07-10-2003, 09:46 AM

You are going to have to dyno it. It depends on the talent level of the port and polish artist. How detailed in the bowls and such. It could be as little as 10 to 15HP gain and as much as 70HP gain (!!!) or more...depending again on the talent.

I have seen a real pro in action taling a measly little mazda truck engine from 85HP to over 150 horses just from intake work, bigger jetterd carbs, head port and polishing and exhaust.

Dyno is the only way to actually tell. Different techniques yield different results.

Dream240 · 07-10-2003, 09:54 AM

Hey you lucked out with the fastback. I noticed you have pro kit springs. Sonce you plan on getting KYB AGX struts, go with Sportline springs. Higher spring rate for the AGXs to play with. Escpecially when you raise the dials to the track settings(all the way up!!)

I would just try to trade them on this site or sell them for a small loss and get some sportlines. Trust me you'll like the perfomance alot better. I have the Sportlines with AGX setup and when I dial my struts up the car really corners like it's on rails!!. And that's without strut tower bars!

As for the porting, I am wanting to rebuild my motor and get that done also, I'm expecting to get about 15 horses. Another side benefit is that you a working toward building that bullet proof engine, and with porting, turbo and NOS will yield greater gains with less boost, thereby making it safer and just as effective running lower boost (10-14). Just my ideas spinning around.....

Good luck!!

rufrydrsc2 · 07-12-2003, 10:20 AM

Yeah, I'm planning on going about 15psi on the turbo, no more. This is going to be a daily driver that will eventually turn into a weekend driver. I have to keep it liveable for my wife so that's why I got the Pro-kits because they would give better driveability on everyday trips, but being progressive rate springs they would get stiff when needed.

07-10-2003, 09:34 AM	#1
rufrydrsc2 Leaky Injector Join Date: Jun 2003 Location: Clinton, South Carolina Age: 45 Posts: 54 Trader Rating: (0) Feedback Score: 0 reviews	Porting and Polishing I had my motor rebuilt top and bottom end, bored, ported and polished. I didn't get a stock dyno to compare it to, but I was just curious how much hp gain I could probably expect from Porting and Polishing. I can definately feel the difference after the rebuild, plus the fact that I had the shop gut my transmission and build me a new one completely from scratch. I have an automatic but it would bark my old tires shifting from first to second as they were just radials. It won't bark my Toyo Proxies, but they are pretty sticky. I know what yall are all saying in your heads, a damn automatic, but it's a good transmission. It has a very instant on feel to it. It hits hard into each gear nomatter if you're driving easy or hard (definately from the build). I'm going to go turbo at around 15psi hopefully before this winter and was just wondering about what I am getting from each modification before then. I don't see alot of people that have gotten porting and polishing done on here, or at least they don't say so in their mods. Is it a common mod on 240's? I am really new to 240's as I am a mustang guy, but my wife owned a '91 240 hatchback when we got married and has since given me permission to (quote "do what you want to it"). Future mods before the turbo are KYB AGX shocks, Eibach pro-kits (which I'm carrying around in the trunk right now), MSDS header, and an Apex-i N1 dual exhaust. __________________ It's impossible to outswim a shark, but easy to outswim your friend. Last edited by rufrydrsc2; 07-10-2003 at 09:39 AM..

07-10-2003, 09:54 AM	#3
Dream240 Nissanaholic! Join Date: Dec 2002 Location: Inland Empire, California Age: 46 Posts: 2,188 Trader Rating: (8) Feedback Score: 8 reviews	Hey you lucked out with the fastback. I noticed you have pro kit springs. Sonce you plan on getting KYB AGX struts, go with Sportline springs. Higher spring rate for the AGXs to play with. Escpecially when you raise the dials to the track settings(all the way up!!) I would just try to trade them on this site or sell them for a small loss and get some sportlines. Trust me you'll like the perfomance alot better. I have the Sportlines with AGX setup and when I dial my struts up the car really corners like it's on rails!!. And that's without strut tower bars! As for the porting, I am wanting to rebuild my motor and get that done also, I'm expecting to get about 15 horses. Another side benefit is that you a working toward building that bullet proof engine, and with porting, turbo and NOS will yield greater gains with less boost, thereby making it safer and just as effective running lower boost (10-14). Just my ideas spinning around..... Good luck!! __________________ Don't mess with my monkey...he's loaded.

07-12-2003, 10:20 AM	#4
rufrydrsc2 Leaky Injector Join Date: Jun 2003 Location: Clinton, South Carolina Age: 45 Posts: 54 Trader Rating: (0) Feedback Score: 0 reviews	Yeah, I'm planning on going about 15psi on the turbo, no more. This is going to be a daily driver that will eventually turn into a weekend driver. I have to keep it liveable for my wife so that's why I got the Pro-kits because they would give better driveability on everyday trips, but being progressive rate springs they would get stiff when needed. __________________ It's impossible to outswim a shark, but easy to outswim your friend.

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07-10-2003, 09:46 AM	#2
Bill Roberts Zilvia FREAK! Join Date: May 2003 Location: S FL. Posts: 1,538 Trader Rating: (0) Feedback Score: 0 reviews	You are going to have to dyno it. It depends on the talent level of the port and polish artist. How detailed in the bowls and such. It could be as little as 10 to 15HP gain and as much as 70HP gain (!!!) or more...depending again on the talent. I have seen a real pro in action taling a measly little mazda truck engine from 85HP to over 150 horses just from intake work, bigger jetterd carbs, head port and polishing and exhaust. Dyno is the only way to actually tell. Different techniques yield different results.