if it shows it, scan me a diagram of the engine block...how to remove the heads...etc... as if you were going to do a port and polish. I have been considering doing this and I would like to do it myself/get some help on it. If you can scan it and e-mail it to PiotrC70@hotmail.com I would appreciate it... Thank you in advance for any help.

 

You need much more than a diagram of the engine block. You need an instruction sequence, torque specifications, and head bolt torquing pattern. Do yourself a favor and get a manual. You don't need the factory book for this work, Chilton or Haynes will do. You can buy this book at any large bookstore (Barnes & Noble, BookStar, Borders) or auto parts store (AutoZone,etc.). You may find it on the shelf at your local public library.

In my opinion the port and polish is a waste of time. You'll never notice any improvement. Save your money... but buy that manual anyway.

 

In my opinion the port and polish is a waste of time. You'll never notice any improvement. Save your money... but buy that manual anyway. [/I][/QUOTE]

How can you say that it is a waste of time and you won't notice any improvement??? This place Z-sport (deals mainly w/ nissans) said they would do the job for about $1600 or so with all the fittings and seals changed and it wouldn't be unreasonable to see 20-30 HP or so....
First of all, I would think that doing it, you WOULD see an improvement because you're allowing more air to flow through... People on here are doing there intake manifolds and seeing about 10 HP or so... I would think that would be like saying that a CAI wouldn't add HP...

 

First off, I was stating an opinion... and labelled it as an opinion. I cannot comment on the veracity of Z-sport, but you should recognize that they are trying to sell something and for that reason might not be totally objective.

It might help to review the history of "port and polish". This modification technique was practiced for many years on US-made V8 engines which had sand-cast iron engine blocks, cylinder heads, and manifolds. At that time manufacturing technology was less evolved than now, and "core shift" was a problem. They handled the problem by making the casting wall thickness large enough to tolerate some core shift. As a consequences of this, (a) most manifold passages didn't line up perfectly with their corresponding cylinder head passages, and (b) those castings had lots of extra "meat" which could be ground away. This grinding, done mostly by a human operator using a pneumatic die grinder, enlarged the passages, smoothed their walls, and matched their positions. There was a genuine performance benefit obtained, mostly at high RPMs.

Contrast the old manufacturing methods with today's die casting of aluminum alloys to close tolerances. You no longer have thick casting walls. You no longer have manifold-to-head passages which are poorly aligned. The problems which were solved by port and polish don't exist any more, so the potential benefit from port and polish doesn't exist any more.

Another technology change affects this debate. Those cast iron V8 engines had only two valves per cylinder. Today, four valves per cylinder are commonplace. This has improved air flow so much that the impediments addressed by port and polish are insignificant.

You may agree or disagree with a stated opinion. I've now given some facts which support my opinion. If you can disprove those facts, please do so.

 

I pity the fool that tries to prove DBM wrong.

The physics dude strikes again with real knowledge and helpful opinions!!!! By the way I think this is the first time anyone has doubted your knowledge. Damn.

 

I meant the DIY dude, not the physics dude, no offense Chris.

Oh well while I'm at it...
20 to 30 HP from a port & polish??? COME ON!!! Don't you have Gran Turismo for your playstation? You NEVER get that much HP from a port & polish, more like 5-10. You might get 20 HP if you're starting with a 500 HP engine! at least that's how it works in GT & GT2.
hehe

Save your money for an SC, if you've got 1600 bucks to drop on this, then just wait awhile longer and go for a *real* performance gain.

Justin

 

Daniel, didn't read the opinion part...sorry... This place Z-sport is very credited here and have worked on nissan's forever...
The guy who works there that did my friends auto to manual swap was the one who told me the info... okay, 30HP could be off and no I'm not talking GT or GT2... but he DID say 20hp you can see. I wasn't planning to blow $1600 on this mod. I know someone who has done it on other cars and was planning to go through him... I did know about what you were talking about but not in so much detail. This post wasn't inteded so that we can argue about who's right or wrong because most of us can't fathom squeezing out 1000hp out of a straight six or 496hp out of a 1.8T
Anyways, those are my thoughts..

 

Likewise, it was not my intention to be argumentive. I hoped to save you money and avoid disappointment. I'm not saying port and polish is useless. I hold the opinion that
(1) port and polish is an expensive procedure,
(2) it will not produce the 20 - 30 hp you cited,
so consequently (3) it's not worth doing.

 

All kidding aside....
I only mentioned GT and GT2 cuz that's the only place I would consider blowing so much money on a mod like that. Anyway, I honestly think your Z-Sport guys are trying to boost their bottom line by selling labor that just won't get you much extra power. The issue here pivots on the idea that porting and polishing can do so much for a well made, light-weight japanese engine. If so, it's worth it - lots of extra HP without the noise of exhaust mods; if not, it's wasted time & money. I haven't heard anyone else chime in on this one, but I really believe it's wasted money. But wait... If you get it done anyways, and prove me wrong...
Well let's just say it wouldn't be the first time.

Good luck dude.


Justin

 

Okay guys... thanks for the opinions... Trust me, I wasn't planning on blowing $1600 on this mod. Like I mentioned, a friend of mine has done it on other cars...Civic's, Integra's.. that sort of thing. He would charge me very little to have it done as long as I help him, which is what I would intend to do. I know it would be time consuming but hey, I'd like to look back and say that I've done it....
Thanks anyways