up to 100hp on pp head

[90drftsx]

For everyone that says you dont gain much from a port and polish head, well i just bought the July 07 modified mag and they have a write up on port and polishing a sr head. HeadGames did the head work. What was done was:

stick with stock size valves for "crisp throttle response"
Ferrea Racing Components competition plus valves "which are made of a special alloy that not only withstands the stress associated with boost or nitrous, but also safeguards against catastrophic engine failure by bending rather than breaking the way a stock valve will."
Ferrea lightweight titanium retainers and valve locks
Jum Wolf bronze valve guides it says that the bronze valves are able to take heat away from the valves much more efficiently and wont break apart ike cast iton units.
HeadGames then ported the head
five angle job on the intake and a radius valve job on the exhaust
port mtached the lower intake mani to the head.
"When people call, they usually say there looking to make 400+hp and they want the biggest valves they can buy. Unfortunately these very things are what would hurt performance of 400+hp car because the valve will be shrouded by the cylinder wall that has not been bored and does not have enough cam to match the big port or the big valve simply because it would be unusable on the street. Just putting a bigger valve in a head will not increase performance by itself. Other preparations must be made to accompany the larger valve such as the port and cam, and intended RPM of the engine. Engine size, and compression and how big of a turbo youre using all play a part in choosing valve size and port design. When we ported the aforementioned SR20det head we stuck with the stock entrance of the port and made all of our modifications inside the port. People can expect up to 100whp with this type of port design. The stock valve size was chosen because there will be a stock bore and small turbo, instead we make up the airflow and in the valvejob, which is the most critical area of cylinder head portin. A bad valve ob can make or break an otherwise kick *** cylinder head." Hope you guys found this as interesting as i have. Im not tryin to say that you gain alot of hp through any pp head, but i guess what place and the set-up you go with. http://images.nicoclub.com/forums/images/smilies/naughty.gif

[GSXRJJordan]

You have to understand that he's saying you can gain 100hp by improving the flow through the head - this means cams and a great tune also. And yes, I've seen guys with '400hp' setups that couldn't get more than about 310rwhp without cams/intake mani/porting, so I say that number's accurate.

[FRpilot]

yea i saw the magazine at walgreens yesterday while i was picking up some drinks.

i doubt you can get up to 100hp from a ported and polish head. 20-30hp maybe, but 100hp get real. unless it was a big stroker motor with a gt42r or something. i hope no one tries to 'learn' things from stupid car magazines like this. they probably said that to get more business for headgamges or whatever. i only look at those magazines to look at pictures, sometimes ads, and if there are usually nice cars being featured. i believe ivans car is also featured with his monstrous ka turbo. articles in those mags are usually stupid. goes something like.. 'car is fitted with jdm parts all around, motor is fed with 1000cc blitz injectors through a border fuel rail all controled by haltec ems. inside the motor is a stroker kit with complete forged pistons and all the trimmings. etc.'' they list parts as if everythign is so holy and shit. i dont waste my time reading that shit.

maybe 100hp for complete headbuild. cams will net you up to 50-60hp if your other mods support it according to many posts i have read on fa throughout the years and testing by others. people who achieve 50-60hp for cams usually are aiming for 350-400+hp and have the supporting mods necessary such as full-race manifold, at least a gt30r, greddy football, injectors, ems, etc. etc. etc. dont expect 50-60 by buying cams on your stock t25 or t28. most think the sr head flows pretty well and although you can gain like 10-20hp from porting it's usually not worth it unless you are trying to squeeze everything out of your motor. at that point you probably going all out anyways by getting stroker kit, solid lifters, run on 110race fuel, etc.

[BigVinnie]

Not with port and polish alone but combined with other mods it can make upto that...
Clover leaf welding alone makes more power than a P&P.

[burnsauto]

You have to understand that he's saying you can gain 100hp by improving the flow through the head - this means cams and a great tune also. And yes, I've seen guys with '400hp' setups that couldn't get more than about 310rwhp without cams/intake mani/porting, so I say that number's accurate.

+1 its all about properly sizing everything so it all works together nicely. good cames, matched up with a properly sized turbo and a p+p job to go with that. all about having an idea of how much power, and where you want that power to be.

[johngriff]

It takes alot of work. Also I would expect to see that kind of gain only from forced induction, not from N/A.

My head!
http://www.rpsportengineering.com/nucleus/johngriff.php?itemid=10

Lots of work..

[BigVinnie]

It takes alot of work. Also I would expect to see that kind of gain only from forced induction, not from N/A.

My head!
http://www.rpsportengineering.com/nucleus/johngriff.php?itemid=10

Lots of work..


I'm assuming about 50 hours of work went into your P&P, work looks excellent.
What type of abrasives were you using. The highest I can find is a 320polishing aluminum oxide abrasive. I've been looking for 400grit and 1000grit but I don't know where to look.

[steve shadows]

thats not port and polish on john's head its a cylinder chamber re-shaping for larger bore.

Port and Polish on sr20det heads yields very low results by itself compared to other modifications and other motors response to such work.

There should be a comparison published before and after dyno results regarding this soon on freshalloy. ill be sure to link to here when its up.

Might be done by rs-enthalpy before i get to it though.

Oversized stainless valves and invasive headwork are going to net more gains with very high flow compressor wheels and I would suggest it more for a drag car if were talking sr20det world.

[johngriff]

Yeah, porting the high ports doesn't make much sense for anything under like 600hp. Port Matching, Maybe. Polishing... up for debate, I have heard lots of discussion as to the rough casting surface's ability to atomize fuel better in F/I applications, and that polishing will make atomization worse in the ports. That is something I have yet to deal with first hand.

When attempting to modify the head, you should have the goal set before application of the work. If you head builder is worth a damn, by setting goals with him, there will be good recommendations as to where to go. In the article it sounded like typical "throw the whole parts book at it" magazine mentality.

[Wei240]

well, hopefully this will drum up sales to people who does p&p, for all the dreamers thinking that they'll gain magical 100hp from doing just this...

[BigVinnie]

thats not port and polish on john's head its a cylinder chamber re-shaping for larger bore.


Isn't a re shape also part of the polishing process.... Although it does deal with extrusion, it still needs a polish when it's finished...

[steve shadows]

the quench chamber/zone does, ie the hemi portion of the head, it needs a vavle job as well. Polishing yes.

But not Port Polishing, or Porting _ie removing exess material from ports.

Like john mentioned, port-matching and a proper valve job or de-shrouding of the cylinder head in the valve seat areas will do more on the high-port head.