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Need Some Turbo Advice.....

ido09s

By ido09s,
in Engines & Forced Induction

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ido09s Mentor

ido09s

Posted
Posted

Who doesnt want advice these days :)

Been out of the game for nearly 4 years now and have NFI what to do with the turbo on the RB26.

We are currently running a T78 drag kit ie the bigger T88 exhaust manifold and gate, and want some more power.

Its been on the dyno at Unigroup a couple of times over the last 4 years and we are kinda wondering why it wont make more power.

Engine runs on Caltex E85, which is currently E70, and has recently made 400rwkw on a conservative tune and about 18psi. Its got a set of 264/272 degree 9.15mm lift GReddy cams in it with a Tomei 1mm head gasket. Head has been ported quite thoroughly by Pete at Advan. Has seen near 2 bar of boost but Yavuz said it seems to hit a wall and wont make more power. Yavuz likes to keep us in the dark and lets the drag strip do the talking and with consistant runs over 135mph i can see why, car weighs about 1460kgs with me in it, we dont know what power it has made on near 2 bar boost unfortunately. We are beginning to think it may just be running out of puff as i guess the car would be making close to 650 odd hp at the crank. It comes on full boost by a little over 4000rpm but we want more with the same response if that can be had nowadays which i am sure it can. The less boost we need the better but i do understand that to make power you need boost ;)

Can it be had and what would you use? We would prefer to keep the manifold and gate, the rest would need modificationss no doubt. Are the cams too small?

Unfortuately curently only having internet access at work makes it hard for me to search and see things as work blocks certain free picture hosting sites :(

Any advice is appreciated

Brad

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GTSBoy Grand Master

GTSBoy

Posted
Posted

A couple of things spring to mind. The FP GT35 stuff might be of interest. And you might like to have a look at the Hypergear thread, especially the more recent pages where Stao has been fiddling about with a VNT system. There is a lot more response to be had in the power level where you are now, and both the above areas are worth a look. Even if Stao hasn't got something ready right now, he could probably work something up for you if you were willing to guinea pig it a little bit.

From what I can see from the recent FP thread, there are also some really big turbos in their lineup too, if you want a significant increase in power range.

34GeeTeeTee Grand Master

34GeeTeeTee

Posted
Posted

A couple of things spring to mind. The FP GT35 stuff might be of interest. And you might like to have a look at the Hypergear thread, especially the more recent pages where Stao has been fiddling about with a VNT system. There is a lot more response to be had in the power level where you are now, and both the above areas are worth a look. Even if Stao hasn't got something ready right now, he could probably work something up for you if you were willing to guinea pig it a little bit.

From what I can see from the recent FP thread, there are also some really big turbos in their lineup too, if you want a significant increase in power range.

This :yes:

Lithium Grand Master

Lithium

Posted
Posted

why are you all suggesting a new turbo isn't a t78 good for 500killerwasps anyway?

That's kindof what I was thinking too - need more specific details if we're going to suggest anything, even if a suggestion is "keep the turbo and try and work out why the setup isn't performing as it should". >135mph is pretty broad (145mph is 135mph+), and 650hp @ crank on alcohol is not that flash for a T78.... also, full boost at just over 4000rpm is pretty surprising too. Are you still running 2.6litres? I'd say a PT6766 or HTA3794 won't spool that well, but then I wouldn't expect a T78 or T88 too either so makes me wonder if there is a chance detail is missing? And how much are you likely to spend?

At this stage going face value that you currently have a T78 and want more power and as good spool as possible I'd be leaning towards a PT6466 but depends on if more detail comes to light :)

GTScotT Grand Master

GTScotT

Posted
Posted

Am guessing this is a T4 twin scroll, so PT6466 would be my choice.

But... Like the others im concerned that the T78 A: should make more and B: should be laggier.

maybe a cam timing or some sort of electrical ignition based issue.. maybe not triggering right and can't get enough timing into it.

ido09s Mentor

ido09s

Posted
  • Author
Posted (edited)

What sort of detail do you need?

the head is pretty heavily ported and far from standard hence the reason it comes on early. Its not the first engine with a T78 Advan has built that works this well either.

Dollars wise this is where it gets tricky. Given we already have a pretty decent set up i would like to spend as little as posible. I really do not want to have to sell the turbo kit and start fresh so ideally would like to keep the manifold and gate. I know the dump will probably need to be modified and a new intake pipe and some cooler pipework fabbed up but thats ideally where i would like to stop.

I am probably asking for too much, but having been out of the game for 4 years i was simply wondering if there was anything out there that may fit my bill now.

The timing is definitely right. The new Ross Balacer trigger setup for RB26 was developed on our car and we have the prototype on it still. There is most definitely no timing issues.

Spark wise its all sorted. We did have issues but since going after market ignitor its made a world of difference.

Edited by ido09s
Lithium Grand Master

Lithium

Posted
Posted

Detail - I guess some confirmation it is DEFINITELY a T78 somehow, and that you have a T4 twin scroll flange like is being assumed, and really it's a shame there are no ACTUAL dyno numbers/curve and that it is definitely a 2.6 litre still.

If all that is true, I actually don't know how you are getting full boost at just over 4000rpm. I've met a T78-33D 2.6litre GTR before and it was laggy as hell - guessing yours may be a 29D?

If it is a 29D, you're trying to save money, and want make a bit more power and keep optimal spool then maybe one of these might be worth looking at: http://www.extremeturbosystems.com/Precision-PTE-6266-CEA-Billet-Turbocharger.html

The 6466 would be better, but they are a good amount more expensive.

ido09s Mentor

ido09s

Posted
  • Author
Posted (edited)

Definitely a 33D, definitely a 2.6 and yes a twin scroll manifold. Its the stock T88 GReddy manifold. They called it the drag kit BITD as it was esentially an 88 kit with a 78 turbo.

I guess this thread has gone a bit off track as people are looking too heavily at the dyno number and not at the turbo being used.The T78 is an air pump thats rated to about 750hp but would like to know what is a step above that isnt a hop step and jump ahead.

Garrett only make a GTX35 and then a GTX4202 which is a huge jump. I could go a Garrett T51 SPL but as i cant find someone who has one fitted to a similar setup its hard to make a decision.

I havent looked at Precision turbo's so i may have a chat with GAS to see they reckon and what they can supply

I may consider a new pair of cams but time will tell. A bit more duration and lift may help but at what cost?

Edited by ido09s
Lithium Grand Master

Lithium

Posted
Posted

Definitely a 33D, definitely a 2.6 and yes a twin scroll manifold. Its the stock T88 GReddy manifold. They called it the drag kit BITD as it was esentially an 88 kit with a 78 turbo.

I guess this thread has gone a bit off track as people are looking too heavily at the dyno number and not at the turbo being used.The T78 is an air pump thats rated to about 750hp but would like to know what is a step above that isnt a hop step and jump ahead.

Garrett only make a GTX35 and then a GTX4202 which is a huge jump. I could go a Garrett T51 SPL but as i cant find someone who has one fitted its hard to make a decision.

I havent looked at Precision turbo's so i may have a chat with GAS to see they reckon and what they can supply

I may consider a new pair of cams but time will tell. A bit more duration and lift may help but at what cost?

OK I will just assume it is a T78-33D air pump and trust you have the rest of the setup optimised then :)

Garrett make a GT4094R, GT4294R and GTX4294R which respond and flow between those two turbos - though I'd sooner see something like the Super94 HTA, which is currently $1899US which is VERY good value for the performance it offers. FP only have .85 T3 listed there, but if you got in touch with them there may be a chance they can sort out a T4 housing for you... I honestly don't know. Good thing about it is you are unlikely to ever need to upgrade beyond that, despite it not being GT42 sized! In essence it'd be like have a GT4202R that is more in the realms of the T78-33D in spool.

A Precision PT6466 BB is the other option - a step down in lag and spool from the HTA and the most conservative option - definitely has T4 twin scroll option.

Those two are basically the magic units for upgrading from the performance balance you are currently getting IMHO. If you went up to the lag level of the 6766 then you may as well go HTA (so long as you can get the T4).

  • 2 weeks later...
ido09s Mentor

ido09s

Posted
  • Author
Posted

Thanks for all the advice guys

Looking like a 6466 is going to be the go as its got some rear housing options to enable us to muck around with things and it should keep us happy for a while ;) The GAS R34 has one on it and they claim they are seeing boost at 3000rpm and making around 550kw atw's which is definitely a step up from the T78 that we are looking for

Now to try and find some dyno graphs

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