Help Me Choose A New Turbo Setup

[Mr. Keets]

Adam, I have the same turbos as you all be it not on a built engine like yours ; both combos are tuned by Ant.

If your chasing 450whp just go a little more boost, mine makes 430rwhp all day no probs...yet lol. As for the response; I would go for some smaller cams. Ultimately Johns' step 1 HKS kit looks the way to go...again tuned by the same guy on the same dyno. John is making 100whp more than mine at the same speed with essentially the same turbos, 2530/2860-5.

In the end there is always a trade off between response and power...unless you have one of those freaky bespoke Racepace strokers...2.95 combos SR rods on a custom billet crank...

ooops edit the capacity of the Racepace. Cheers Steve

[Crans]

If im reading that chart correctly HKS 2510's will do around 440hp atw??

I have them on my gtr but havnt driven it yet due to some problems. What what i have heard there response is amazing while still making good power

[badgtr34]

i just had tomei poncams in my gtr and changed them back for stock rb26 cams.. running -5's and got better response and boost came on slightly earlier which you want want with those turbos.

[Slide]

  NickR33 said:

damn you Slide

how would these compare to the T517z 8cms?

Purely a theoretical question because I'm not planning on changing turbos... anytime soon

back on topic, I would listen to what Ash said about cams... your cams would be setup for making peak power well over 6000rpm... they have massive overlap

We have only ever had the 10cm's and they achieve 350awkw at around 18 pound without head work.

They hit that boost pressure at roughly 4400rpm

With a 2.8LTR Tomei kit we have achieved 400awkw at 1.6 Bar

Boost at 4000 with poncams.

Its a good kit.

[NickR33]

I have 8cms and they make 360rwkw at 20psi... hits 20 by about 4000rpm... would be nice to have another 100kw at the same rpm lol... it has Procams in it so it has a very strong top end but it could do with a change to smaller cams but I'm going to leave it as is for a while and see how it goes

[discopotato03]

Does anyone know the actual valve timing numbers for these "272" cams ?

I was just looking at Tighe rally Subaru cam specs recently and they were ~ 270 degrees , I think the valve timing numbers were about 25-65 67 23 . This gives an overlap of 48 degrees and not surprisingly the engines run like chaff cutters .

I wouldn't expect an RB26 with numbers like these to pull hard in the lower mid range no matter what turbos it had .

To make torque you have to have sufficient cylinder pressure in the relevant engine rev range and if you use longer duration cams with lots of overlap the trapping efficiency of the valves/cylinders is nowhere until the mass of the gasses carries them in the right directions .

I reckon use milder profile cams and see what happens with the turbos you have .

BTW -9's are the GTSS's not -7's .

Turbo wise if you wanted to build bitzers from Garrett cartridges the one I'd look at is the one from the SR20 spec "GTSS" GT2860R . These have the NS111 turbine found in GT2860RS's/GT2530's etc but the compressor wheel is the 60.1mm 60T . They are intended to be a mild bolt on for an SR20 but with GTR style housings they would be just a little tamer than a 2860RS or 2530 .

Three things pull the bottom end up with GTR spec GTss's/-9's compared to 2530's .

Firstly their turbines are 10 bladed 62 trim where the better NS111 ones are 9 bladed 76 trim .

Secondly their compressor wheels are 59.7mm 56 trim where the 2530's are 60.1mm 63 trim .

Thirdly the compressor housings are T3 dimensionally where 2530s are supposed to be T04B .

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