What Turbo, Cams, Valve Springs, Valves, Head Work Do I Get?

[kitto]

Evening all!

So its now time for me to start choosing what top end parts i need to start ordering for my RB26 engine.

So far i've pretty much got the bottom end sorted out parts wise.

I have;

CP Pistons

Carrillo Rods with CARR bolts

Tomei oil pump

ATI Harmonic Balancer

ARP Main studs

ARP Head studs

Full gasket kit

N1 Water pump

Gates Belt

Few other bits and pieces.

No bearings as yet - engine builder will need to size them up

I'm trying to go as far as i can with this engine whilst keeping it relatively simple.

I'm chasing reliability, longevity, response and efficiency. Not necessarily raw power. Im going as far as i can oil control wise, i have that more or less sorted. Power output in mind 400rw kW.

So now i'm moving onto the head and what parts i should be looking at and what head work I should be looking at getting done.

Turbo; I've done a fair bit of talking to people and so far the GTX3076R with a .82 rear housing is what everyone seems to be suggesting to me so far. Most people with RB25's are running these or the 3071R with a .63 housing. But as i have an RB26 with a more efficient flowing head and i'm considering porting aswell. The .82 rear housing should suit nicely. Please do not suggest that i stick with twin turbos, i have made my mind up on a larger single turbo for several reasons.

Wastegate; This is something i'm really guessing now, I'm personally thinking something like a 48 or 50mm gate, brands?

Manifold: Garage 7 steam pipe

Cams: I'm looking at a pair of Camtech Cams. Ideally for what i'm doing, i should be going for maximum lift and not going to crazy on duration. So something like a 270, 278 or 280 duration with 10.8mm lift. Obviously its preferable to not machine the head to clear the bigger 11.5mm lift cams.

Here's their webpage so you can have a looksie; http://www.camtechcams.com.au/niss_6cyl_rb26.html

Head internals: Now, how far do i really go? I have Tomei gear set in my head, but do i really need to buy everything Tomei?

Oversize Valve

Valve springs

Valve guides

Valve Seats

Solid lifters

Valve spring shims

What should i really be replacing? Should i be replacing it all to have the best chance of a nice reliable engine that is able to easily make nice power for years to come. I've been told to replace the valve guides with bronze items, i've been told the factory exhaust valves tend to snap off at high revs. Valve springs will definitely need to be changed, but do i go type A, B or C?

What other brands could i be looking at that is comparable to Tomei, HKS etc? Maybe Ferrera Valves, Supertech Valve springs and valve guides etc.

And how far should i be taking my porting, just cleaning up the ports, such as removing the stud recess in the exhaust ports, or should i be really opening them up and gasket matching the intake and exhaust ports.

Any input will be greatly appreciated!

Cheers, Daniel.

[JonnoHR31]

stock

[kitto]

stock

I still to this day can't work out your fascination with keeping everything stock.... Stock shit doesn't always hold up....

[N1GTR]

First thing's first; a GTX3076 flowing mid 400rwkw?

[JonnoHR31]

not gonna happen, hence why i suggest stock bits. .82 gt30 housing isnt gonna flow anywhere near the limits of a standard 26 head

[R31Nismoid]

^ Ye +1

First thing's first; a GTX3076 flowing mid 400rwkw?

I can bet my balls i know where he is getting that "advice" from.

But ye, not a chance that turbo will crack more than a legit 360-380rwkw. 400rwkw is a dream. Plus it's RWD 400rwkw without some serious wide-body/overtyre action simply isn't going to happen.

Hy GTS-R was utterly undriveable with 370rwkw, was sideways coming onto boost in 4th. Without basically redesigning the rear end traction is not going to occur

Plus 278.280 cams are a bad choice for a turbo so small. Especially when "response and efficiency" are listed in the first post.

Such oversized cams are FAR too big to be responsive.

I still to this day can't work out your fascination with keeping everything stock.... Stock shit doesn't always hold up....

Well i have stock:

gearbox / plenum / block / piping / cooler / ignition / cams & valvetrain / balancer / rods & crank

Holding up high 300rwkw fine, as have countless other setups. Sees 8000rpm & the limiter regularly. Stock shit holds fine if you know what you are doing.

Infact i probably have more stock bits, thats all i can think of @ this hour of the morning.

[kitto]

Ok, maybe i should re-phrase this a little.

I know 400kW in a RWD vehicle is going to be a handful, i'm aware of this. Realistically it will be tuned for 350kW. I want to build this engine so that say in 5 years time i decide to buy a GTR, i can put this engine straight in, slap on a larger turbo, change the cams and injectors if need be and push out 400kW+ if i decide to do this.

So i'm trying to do all the internals now so that i dont have to open up the engine later on down the track.

I know the GTX3076R wiht a .63 housing can make 366kW on an internally stock RB25 NEO. (Simon Michelmore's S14). The same tuner will be tuning my engine once it is built.

I do believe that simon is not actually running the turbo in its proper efficiency range, I dont think he's making full use of the turbo.

So lets be realistic then, lets say i chase 350 - 380kW for my RWD car. Firstly, Turbo, is the 3076R with a .82 housing going to be a good choice? Or are there some other turbos you would suggest? That then brings us to external gate size and brand once turbo choice has been made.

Cams, yes i had a feeling anything over 270 duration is going to be far to aggressive. Should i be going a pair of 264's with as much lift as possible or even sticking with stock cams? I already have adjustable cam gears.

I'd really like to do some sort of head work. It will be getting revved hard and for long periods of time, so valve springs are a definate. It would be nice to at least clean up the ports and match them a bit better. I know oversize valves may not be necessary but after talking to several reputable engine builders, a few have said the exhaust valves tend to fail at constant high RPM. This was not something i was aware of. Valve guides is another one that was suggest to change to bronze items. That then brings us to valve seats and lifters. I'm sure the factory lifters will be fine, as long as they are not worn out. Of course they will need to be re-shimmed.

[R31Nismoid]

366kw @ the hubs, don't forget that isn't @ the wheels. No way a .63 makes that power @ rear wheels, 320rwkw would be more realistic (on E85)

You need a GT35 with a .82 rear end, tried and proven to do exactly what you want. I believe Dan/Noel have been doing work with a GT3788 (and other VCT stuff) however I'm yet to see them post results but it sounds like interesting developments. Hopefully he can comment further. I think they make closer to 400rwkw however.

After 5 years of racing a motor, if you are pulling it out and putting into another car. Without question you should be pulling it down and rebuild/refresh it anyway mate. No doubt a fresh set of bearings and rings at the very least just for the bottom end.

What RPM are you looking at using? A 650-700hp turbo (.82 rear is required) you really wont need more than 8,000rpm.

There are countless GTRs here with stock valves/cams and making between 330-380rwkw. And these heads have been rebuilt so springs replaced and so on - so they aren't old.

Are they "tending to fail" on 10-15yr old heads? Cause without a doubt i would agree in that instance its a reliability issue, any 15yr old head would be.

I guess at the end of the day what is your overall budget? That is always a good starting point, even if it is @ the end of my post

I say this because if you settle for say 320-330rwkw now, why not save money now and then add on extra stuff when you freshen up in 4-5 years time? It wont really cost you anything extra given it's getting refreshed anyway. That's exactly what i would be doing IMO.

[XRATED]

Evening all!

I'm trying to go as far as i can with this engine whilst keeping it relatively simple.

I'm chasing reliability, longevity, response and efficiency. Not necessarily raw power. Im going as far as i can oil control wise, i have that more or less sorted. Power output in mind 400rw kW.

So now i'm moving onto the head and what parts i should be looking at and what head work I should be looking at getting done.

Wastegate; This is something i'm really guessing now, I'm personally thinking something like a 48 or 50mm gate, brands?

Manifold: Garage 7 steam pipe

Cams:

Head internals: Now, how far do i really go? I have Tomei gear set in my head, but do i really need to buy everything Tomei?

Oversize Valve

Valve springs

Valve guides

Valve Seats

Solid lifters

Valve spring shims

And how far should i be taking my porting, just cleaning up the ports, such as removing the stud recess in the exhaust ports, or should i be really opening them up and gasket matching the intake and exhaust ports.

Any input will be greatly appreciated!

Cheers, Daniel.

Basic tidy up of the ports/casting marks, nothing crazy... leave the exhaust humps alone! re-fresh anything that needs it eg, valve seats/guides/seals etc.. Don't bother with oversize valves ffs! 260deg pon cams will be more than enough. Maybe some supertech guides, valve spings and retainers for peice of mind.

26 heads have solid lifters allready...

50mm turbosmart progate. Dosn't really matter, just dont buy a dodgy copy pos.

Arp head bolts

If you want it to last longer... keep the power range optimised around 350-380 rwkw anf the revs down around 7.5/8k

J.

[GTScotT]

You need to pick a bigger turbo, and I cant even be bothered to suggest one.......

400kw is a bloody hard number.. And its not of GT30 range..

Please read the over 400kw thread...... Please.

[kitto]

366kw @ the hubs, don't forget that isn't @ the wheels. No way a .63 makes that power @ rear wheels, 320rwkw would be more realistic (on E85)

Ah yes, good point, well my car will be tuned on the same dyno. Wheel dyno's are so hit and miss so who really knows how much power x car makes on x wheel dyno.

You need a GT35 with a .82 rear end, tried and proven to do exactly what you want.

Ok, so maybe a GT3540 with a .82 rear housing? I can't say i've compared the specs closely of the 3540 and the GTX3076R, but i'm assuming i'll have a little more lag with different turbine and compressor trims.

What RPM are you looking at using?

8,500RPM max, limiter will be set slightly higher than max power. So it may make full power at 7,200 or whatever. So limiter might be set to 7,500RPM

And these heads have been rebuilt so springs replaced and so on - so they aren't old.

But have the valves and and valve seats been replaced, as they are commonly overlooked.

I guess at the end of the day what is your overall budget?

Well i'm going to well and truely blow my $12k budget for the long engine. So i'm not so sure anymore haha.

leave the exhaust humps alone! Don't bother with oversize valves ffs!

Why and why?

26 heads have solid lifters allready...

Yes i know this, i'd only need the Tomei solid lifters if i were putting it rediculous lift cams yes? As the base circle diameter of the cam changes on the larger lift cams.

Arp head bolts

Already doing them...

[black bnr32]

consider a twin scroll turbo and exhaust manifold

[tk80]

am building mine right now also, but mine has -5 turbo's.

i'm already running poncams (260 9.15mm) and going to test out how they go in the new motor.

about to order the supertech head gear.....valves, springs (dual), retainers and locks. My goal is also 400awkw for a reliable track car and have been told that is all i'll need. Unsure what 'cleaning up' work the builder is going to do while he's in there.....but will let you know.

on another note i'm trying to have the compression ratio around 9:1 (vs std 8.5:1) to help with response as even -5's are a bit laggy at times. might even go higher if the engine builder thinks it's doable as i'll be running e85 so i won't run into any fuel issues.

Edited August 2, 2011 by tk80

[usmair]

I know there was a whole hoo haa over their dyno numbers so even if you take 20-25kw of the number is still around the 350rwkw mark

this would be the .82 housing though

[NYTSKY]

Nice thread dig, you will find that to achieve that power boost was well into the 30psi area.

[GTR_JOEY]

consider a twin scroll turbo and exhaust manifold

you can add another 2-3 grand to your bill if you wanna take that path

[BLITZ-26]

Refresh head, fit pon cams and cam gears new valve springs dont bother with over size valves will increase top end but non bottom.... focus your money you would have blown on the head on the turbo setup my pick would be a twin scroll gtx35r 1.06 rear with twin tial 44mm gates

[SimonR32]

I know there was a whole hoo haa over their dyno numbers so even if you take 20-25kw of the number is still around the 350rwkw mark

this would be the .82 housing though

See the nice thing down the bottom right of the graph saying "Temp Probe Fault"?

Correction is a wonderful thing

[R31Nismoid]

[kitto]

Wow at the thread revival.

Since this thread i really did change my plans

NOW RB25DET NEO

Mild head porting

Heavy duty valve springs

Factory cams (keeping VCT)

Factory valves and guides

Garage 7 steam pipe manifold

GTX3076 w/ .63 rear housing

Ill be happy with 320-350 kW @ the hubs which this will shit out on E85.

My RB26 build came to a screaming hault for many reasons.