Building A Head (25/26)

[carpark]

hey everybody,

i just got back from whinton drift day today. I was riding shotgun in a mates R32 bronski and it got me thinking i really do need more power.

As i am on my P's and want to keep my insurence i was thinking head work?

i have been flicking through and havent really found a usefull guide for building a tough N/A head.

So anybody looking to post there past experiences or there own personal opinion feel more than welcome.

I would like all sorts of info such as:

-cams (obviously) duration and lift values.

-springs

-porting

-larger valves

thank you everyone

[PM-R33]

You won't find much info because building a proper head (especially a N/A one) is a black art. The people that know what they are doing charge huge amounts of money for their talent. No one will be willing to simply give away their secrets for free.

Obviously you could get larger custom ground camshafts, open up the ports and upgrade the valve train, but really at the end of the day, it aint going to bring you much power for the amount of money it will cost you; and it will cost you a LOT. Even with a tuned length exhaust manifold and individual throttle bodies your power increases are still relatively small.

You are on your P's. Have fun with the car as it is, once you get off your P's buy something else if you want power.

N/A Skylines are simply not made to make power, end of story. They are far to heavy for the size N/A engines they have.

[carpark]

thanks for your opinion and it seems like a wise one, well somehow in japan they can make a comfortable 300hp. but i would imagine that would be more than just a little head work. Im not looking for that much more power just enough so it revs up a little quicker. obviously I will need a light flywheel and driveshaft etc for less unsprung weight. Well if these people value there knowledge and ask for many coins, do you know where i could find someone or who would u recomend around melbourne?

[PM-R33]

Not sure about Melbourne sorry, but just give Trent a call at Status (Think it is Checkered Tuning now?) and see what he says.

At the end of the day, if some one told me I had to build a NA RB to make power it obviously is possible, but not cheap at all.

Making power out of a NA RB is the same as making power out of any NA engine. I would try to chase power through high compression, higher displacement, high revs and high air velocity.

RB30 block with a NA RB25 head.

Custom high compression light weight pistons, light weight balanced rods and crank to bring compression up to something high like 12.1 and run E85 fuel only.

Build the head with large duration and lift cams. Open up the valves with oversized valves.

Heavily port the head and build it and the engine for high RPM depending on where the power band would be.

Individual throttle bodies.

Tuned length extractors.

Light weight pulleys.

Lightened flywheel.

Shot of nitrous oxide.

etc.

As you can see it aint an easy or cheap job and really only doing a part of it aint going to give you much gains without doing the whole lot.

The most I have seen on here from the NA section from a RB25DE is around 130-140rwkw. Which is dick all really.

[waxracing]

try a 26 head with rb25 na pistons

that will get your compression up there.

A good set of cams, get a set of rb30 headers and cut the exhaust flange off weld on a 26 one and there are your headers

The 26 has itb so your good to go there

nice little revy engine if you do it right with lots of torque

Edited December 12, 2010 by waxracing

[JonnoHR31]

http://motamota.r31skylineclub.com/index.php?topic=104694.0

start reading about how much of a waste of money it is

[PM-R33]

Link don't work. Have to log in.

[mystery_kid]

don't waste your time and money on 6 cylinder n/a engines and trying to get power out of them

stick it out on your p's until you get an a turbo or a v8

Edited December 12, 2010 by mystery_kid

[Deano 1]

mate, if you really want to do it, dont listen to all these people that say dont waste ya time and blah blah, just do it. Try do most if not all the work yourself with research put some decent cams in her and just enjoy it, its gunna make more power than it dose now so either way its goin to be a bonus, it wont be as much as a turbo car for the money but its still gunna be somthing diffrent and new to drive till you get off your [p] and at least you can say you did it.

I did it with my first car, r31 rb30e, started out with 84rwkw in a gluged up dirty old 225klm head. Pull it off cleaned up all the ports with a die grinder, put all new seals though it, droped a decent sized custom cam in it from Cam Tech in sydney, made 104rwkw when i was finshed on bp98. was super fun to drive and sounded awesome.... all in all cost me about 2k all up, with the exhaust system, but i did everything myself..... cops couldnt tell a thing, it was just a fast enough car for a P plater and i had a sick time with it.

[GTS4WD]

Unless you have a cool 10K for a tough NA engine.

Forget it

[carpark]

mate, if you really want to do it, dont listen to all these people that say dont waste ya time and blah blah, just do it. Try do most if not all the work yourself with research put some decent cams in her and just enjoy it, its gunna make more power than it dose now so either way its goin to be a bonus, it wont be as much as a turbo car for the money but its still gunna be somthing diffrent and new to drive till you get off your [p] and at least you can say you did it.

I did it with my first car, r31 rb30e, started out with 84rwkw in a gluged up dirty old 225klm head. Pull it off cleaned up all the ports with a die grinder, put all new seals though it, droped a decent sized custom cam in it from Cam Tech in sydney, made 104rwkw when i was finshed on bp98. was super fun to drive and sounded awesome.... all in all cost me about 2k all up, with the exhaust system, but i did everything myself..... cops couldnt tell a thing, it was just a fast enough car for a P plater and i had a sick time with it.

thanks man, this is what i was asking for i really dont care about man hours or labour as i will do it myself with some help from mates, but all i really want to know is what cam is recommended and is it worth getting a crazy cam and changing all the springs and what nots, or just going something mild.

[zebra]

thanks man, this is what i was asking for i really dont care about man hours or labour as i will do it myself with some help from mates, but all i really want to know is what cam is recommended and is it worth getting a crazy cam and changing all the springs and what nots, or just going something mild.

Ok, lets get things straight,

The cost of just parts alone will run into the thousands a set of cams and valve springs is well over 1000 bucks.

But if you were to do it.

I would find a Neo RB25DET head and use it, they have a smaller combustion chamber than the earlier heads so that will up your compression for the larger cams, they also have solid lifters so you can rev them harder.

New rings and bearings in the bottom end, a larger sump will be needed if you plan of revving the bejesus out of it.

For cams I would just go off the Shelf 264's with around 9mm lift, so it stays streetable.

Find a GOOD set of headers, the cheap stuff from ebay or just cheap in general is just shit!

So a custom set done by someone who knows what they are doing would be ideal but expensive, a good hint at a good header builder is when they start asking about cam sizes, port work, expected rpm range etc.

The RB26 ITB setup would be the best bet for the intake, but requires an adaptor made, alteratively a Greddy plenum would work well at higher rpm as well.

Then all you will need would be a good MAP based ECU and TUNE TUNE TUNE!

[TwoCents]

Ok, lets get things straight,

The cost of just parts alone will run into the thousands a set of cams and valve springs is well over 1000 bucks.

But if you were to do it.

I would find a Neo RB25DET head and use it, they have a smaller combustion chamber than the earlier heads so that will up your compression for the larger cams, they also have solid lifters so you can rev them harder.

New rings and bearings in the bottom end, a larger sump will be needed if you plan of revving the bejesus out of it.

For cams I would just go off the Shelf 264's with around 9mm lift, so it stays streetable.

Find a GOOD set of headers, the cheap stuff from ebay or just cheap in general is just shit!

So a custom set done by someone who knows what they are doing would be ideal but expensive, a good hint at a good header builder is when they start asking about cam sizes, port work, expected rpm range etc.

The RB26 ITB setup would be the best bet for the intake, but requires an adaptor made, alteratively a Greddy plenum would work well at higher rpm as well.

Then all you will need would be a good MAP based ECU and TUNE TUNE TUNE!

Couldnt you just regrind the stock cams, adj exhaust cam gear and an aftermarket tuneable ecu. If you already have the right intake and exhaust mods then them 3 things should be enough to give you that little more extra power.

This way the only money being invested on the N/A motor would be the cams as you can use the ecu and adj cam gear in a turbo'd motor when your off your p's.

[zebra]

Sure you could have the cams reground, but wont be as effective.

[Deano 1]

Ok, lets get things straight,

The cost of just parts alone will run into the thousands a set of cams and valve springs is well over 1000 bucks.

But if you were to do it.

I would find a Neo RB25DET head and use it, they have a smaller combustion chamber than the earlier heads so that will up your compression for the larger cams, they also have solid lifters so you can rev them harder.

New rings and bearings in the bottom end, a larger sump will be needed if you plan of revving the bejesus out of it.

For cams I would just go off the Shelf 264's with around 9mm lift, so it stays streetable.

Find a GOOD set of headers, the cheap stuff from ebay or just cheap in general is just shit!

So a custom set done by someone who knows what they are doing would be ideal but expensive, a good hint at a good header builder is when they start asking about cam sizes, port work, expected rpm range etc.

The RB26 ITB setup would be the best bet for the intake, but requires an adaptor made, alteratively a Greddy plenum would work well at higher rpm as well.

Then all you will need would be a good MAP based ECU and TUNE TUNE TUNE!

that sounds awesome and almost worth doing, and at the end of it all, 100shot of gas for the drags....

[zebra]

Yeah I f I ever won lotto I would do it, but really not worth the $$$$ spent when a stock Turbo RB25det would make more power

[carpark]

yes everyone i know a TURBO motor would make more power and be cheaper but as i have said previously i am on my P's. enough said

[carpark]

Ok, lets get things straight,

The cost of just parts alone will run into the thousands a set of cams and valve springs is well over 1000 bucks.

But if you were to do it.

I would find a Neo RB25DET head and use it, they have a smaller combustion chamber than the earlier heads so that will up your compression for the larger cams, they also have solid lifters so you can rev them harder.

New rings and bearings in the bottom end, a larger sump will be needed if you plan of revving the bejesus out of it.

For cams I would just go off the Shelf 264's with around 9mm lift, so it stays streetable.

Find a GOOD set of headers, the cheap stuff from ebay or just cheap in general is just shit!

So a custom set done by someone who knows what they are doing would be ideal but expensive, a good hint at a good header builder is when they start asking about cam sizes, port work, expected rpm range etc.

The RB26 ITB setup would be the best bet for the intake, but requires an adaptor made, alteratively a Greddy plenum would work well at higher rpm as well.

Then all you will need would be a good MAP based ECU and TUNE TUNE TUNE!

thanks,

i already have a set of extractors but they are only a el-cheapo set i got off ebay.

VCT setup? obviously i will be getting rid of that for adjustable cam gears and different cams but will i need a remap/tune before i can run it or will it run with VCT disconnected? obviously it wont run stoich untill i get a tune.

and will i need to change my fuel rail/injector setup if opting for a gtr or greddy intake plenum?

cheers

[zebra]

the car will run with out VCT will just be a bit doughy down low, if you want the GTR plenum then you will need the RB26 fuel rail and injectors to suit, if you use the GReddy plenum then either the standard RB25DE or RB26 rail will work but the topfeed RB26 injectors will need collars made up to fit.

[mad082]

yes everyone i know a TURBO motor would make more power and be cheaper but as i have said previously i am on my P's. enough said

you do realise that what you are actually talking about doing is just as illegal as driving a turbo car? just slightly harder to get booked for. not trying to be patronising or anything like that, just making sure that you are aware of the legal implications of what you are doing.