GT30 Cam Selection

[masTers]

Currently building up a RB30-DET, and its come time to choose cam shafts, now against alot of peoples advice, im still running with a low mount GT30, and was just curious cam selection?

A few people have recomended the Tomei Poncam's but was wondering what others think. I defiently want to go Tomei, be it PON or PRO cam.

Im using the R32 RB25-DE head, so im limited to RB20 cams right?

[R31Nismoid]

If its an RB25 head, you need RB25 cams.

Although, with a GT30 on an RB30det, you will not need cams in the slightest.

Its gonna come on so early that in my opinion there is no need at all. Spend the $$ one something else will gain more benefit

[macka]

R31 could u explain why he wont need cams?

But if he were using an rb25 he would benefit more from cams?

I would be interested to know

[R31Nismoid]

The stock heads are fine upto 300rwkw, mine is going quite well now without problems.

Yeah cams might bring it on a bit earlier etc. But for the price i can spend it elsewhere and get more of a gain.

with a GT30 he wont be pushing much more than 300rwkw if that.

[macka]

So an rb25 Head is at its limit at 300kw or there abouts?

what do u do then?

Mine is ported and standard inlet manifold pushing 311rwkw

[masTers]

I dont seee how an N/A head is capable of 300rwkw? Dont forget that this is the R32 n/a head NOT the R33 one. According to CUBES guide and a few other sources, the cams and springs in this head are useless for boosted applications and are interchangeable with RB20-DET cams and springs.

I thought due to the VVT the R33+ RB25 Cams would be unsuitable?

[rev210]

I would strongly suggest a camshaft upgrade to cater for the larger displacement. There are far greater benifits again for doing this to a big breather like the RB30 hybrid. The Rb30 should quite happily live with larger cams than an Rb25 and the spread of power increase will be more than worth the expense. Even if you go for the pon cam 260deg 9mm lift units, which should not tax the factory springs much given the rpms are lower and the lift not too radical, and the gains will be substancial over the nanna grade cams the Rb25 has from factory.

Even if you had an Rb25 stocker a cam upgrade does wonders when it's set up right.

[R31Nismoid]

So an rb25 Head is at its limit at 300kw or there abouts?

what do u do then?

Mine is ported and standard inlet manifold pushing 311rwkw

how is it performing @ 311rwkw?

got a dyno graph for us to drool over

[180bfj20det]

R31 could u explain why he wont need cams?

But if he were using an rb25 he would benefit more from cams?

I would be interested to know

I think what he is saying is that the GT30 will already be at its limits with the flow capacity of the hybrid 30/25 and that increasing the flow with bigger cams would only change the power delivery more or less rather than outright power. Rather than cams, get at least a GT3540 or personally Id go bigger. Here you will make gains and then later down the track even more with cams but cams with a GT30 are a waste of time and money on that awesome high flowing hybrid. YOU NEED BIG TURBO for this engine....maybe seriously get another GT30, use 0.63 housings on both and youll want cams then....but youll make HUGE power tho with considerable lag I imagine (5.5k up). Im sure there is a GTR that has already this conbination making +400rwkW.

[Gradenko]

If its an RB25 head, you need RB25 cams.

RB20 cams (aftermarket or not) will fit.

Although, with a GT30 on an RB30det, you will not need cams in the slightest.  

Its gonna come on so early that in my opinion there is no need at all. Spend the $$ one something else will gain more benefit

Are you joking? Because I'm not laughing.

[Cubes]

Its an R32 RB25DE head.. You will need the R32 RB20DET cams.

Anything to increase the airflow and reduce the boost required is a good thing.

Increase only the lift and you will increase the average power under the curve, increase only the duration you will increase the rpm at where peak power is made.

Also larger duration hence slightly more overlap does not work well with a restrictive turbine housing and or exhaust.

The N/A stock cams are not useless, however the springs over 17psi are.

The N/A springs don't have enough seat pressure and cause valve float on the inlet.

Replace the springs with a turbo set of springs and the motor will be fine to run big boost.

There's a GT35 internal gate .82 on a Rb30det getting around on this board by the name of Sky30.

Stock cams, stock exh. manifold, gtr valve springs made 290rwkw @6000rpm on ~19psi.

He has a set of Tomei PonCams 260duration coming.

It will be very interestering to see the boost drop and power go upwards.

I have a .82 ARB machined exhaust housing to suit a GT35R, it has provision to bolt an external gate on and bolt up to the stock exh. manifold. It isn't optimal.

The same exhaust housing on another RB30DET with 18-19psi it made 306rwkw. With a garrett gt35r .82 exhaust housing, aftermarket manifold setup properly with the wastegate it made an extra 20rwkw on the same boost.

Obviously the GT35R's love the high boost 25psi range. They are rather efficient up that are of the compressor map.

You select a turbo to suit your power requirements.

If up to 300rwkw is what you want then select a GT30R, if you want over grab your self a GT35R.

The trick with the RB30 is to get a nice free flowing exhaust and turbine housing.

A bare minimum of a .82 exhaust a/r and a 3.5" exhaust (nice big center resonator & rear muffler) will work well with the RB30DET.

[R32-GTS]

The rb30det i know of is making 490rwhp with the r32 rb25na head so they must flow quite well. I have just ordered him rb20 tomei 270 degree cams with 8.8mm lift which makes them a straight bolt in. As the r32 rb25 head has no variable cam timing you have alot bigger choice of cams.

[NickR33]

I would strongly suggest a camshaft upgrade to cater for the larger displacement. There are far greater benifits again for doing this to a big breather like the RB30 hybrid. The Rb30 should quite happily live with larger cams than an Rb25 and the spread of power increase will be more than worth the expense. Even if you go for the pon cam 260deg 9mm lift units, which should not tax the factory springs much given the rpms are lower and the lift not too radical, and the gains will be substancial over the nanna grade cams the Rb25 has from factory.  

Even if you had an Rb25 stocker a cam upgrade does wonders when it's set up right.

It sure does:)

and Ash, your car really sounds like its got aftermarket cams?

[RS500]

 

 

I have a .82 ARB machined exhaust housing to suit a GT35R, it has provision to bolt an external gate on and bolt up to the stock exh. manifold. It isn't optimal.

The same exhaust housing on another RB30DET with 18-19psi it made 306rwkw. With a garrett gt35r .82 exhaust housing, aftermarket manifold setup properly with the wastegate it made an extra 20rwkw on the same boost.

 

dude,

in my experience with a Garrett GT3040R (ARB exhaust housing), i would recommend u get rid of it as it poses a great restriction to the flow of the turbo's gasses.

i would recommend using a genuine GT exhaust housing which was designed for the flow and dynamics of the GT35R exhaust wheel.

the reason i say this is b/c when i had my A/R .82 ARB housing on my turbo (as above), i couldn't make any decent power, even at 20psi, and the back pressure was high (almost 2:1), whereas with the genuine GT A/R .63 housing, we saw the back pressure drop dramatically (almost 1:1) and power picked up noticably.

it's only my opinion, but yeah it's based on my own experience.

[Cubes]

I've since decided to get my self a HKS3037ProS from japland.

It will make the power I want and give me the look I want.

If it wasn't for the police here in SA I would most definitely go for an external gate etc etc.. After having the hood popped the other night It's really made me thing I should step back and go the 3037 with its 45mm internal gate.

The ARB exhaust housing works and makes the power but obviously isn't optimal.

Any 1 want to buy it?

Its got the flange to bolt on a external gate so it will allow you to bolt a GT35R up to the stock exhaust manifold.

[R31Nismoid]

It sure does:)

and Ash, your car really sounds like its got aftermarket cams?

stock RB25det head on my car.

no head work at all

[Cubes]

Ash, Adj. Cam Gears?

Little more overlap? I know the RB30DET with the N/A cams sounds ever ever so slightly cammy. Well compared to the rb20det.

[R31Nismoid]

nope. totally stock down to gears and everything.

Only changed the bottom end gear which isnt power gaining, just power withstanding

I kinad sounds like i have cams just before it comes onto boost/gate as thats where the VCT comes in and when its just feeding in 17-24psi it gives that impression