.86 & .64

[STATUS]

How's this one Trent? PU MAX high flow Profile .63

And you need to start answering people's phone calls man. Ring you lots times for a tune never get answered.

Not bad but i dont like the idea of the actuator stoppers, im worried the excessive exhaust manifold pressures will cause damage down the track.

Only those people that don't listen to our voicemail have issues and honestly if they cant take the time to write emails or leave messages i dont have time for them simple, i run a very busy shop and the customers who do the right thing by listening to the voicemail and reading our website get looked after and booked in quickly and efficiently. I cannot answer a phone and tune at the same time....

[GTScotT]

Cmon play nice..

Lets discuss that actuator stopper, I think its fine. if the actuator was fully open all the time there would be no boost. The same as if it was to hit target boost and sit fully open boost would fall off.

The wastegate flap is constantly regulating at a high rate, and would hardly be open fully to hold target boost, if even open for longer than countable seconds at a time. Therefore I see the wastegate stopper as a means to prevent sudden changes in pressure. The actuator could be reacting too slow as the revs rise and with an obvious increase in manifold pressure I can see how the flap would be pushed open too far and cause it to drop boost.

The issue of pressure in the manifold should be something that could be worked out mathematically AFAIK. We are talking CFM in and CFM out after all.... considering flow = power more or less, as long as the turbine can flow the gas through it at those shaft speeds, I dont think there could be a problem.

Id leave that for Stao to answer tho, he is the one who quote engineers these turbos.

[SimonR32]

I also don't see the difference between a "Wastegate controller" holding the actuator flap closed or something like a stronger HKS actuator holding the flap closed... both will cause increased exhaust manifold pressure

Edited May 18, 2010 by Cerbera

[hypergear]

The wastegate stopper has been changed. I want to give people the full extend of boost control as possible in what ever size engines as possible while still retain the long term sustainability. The new one doesn't work the old way, Please refer to the current PU boost reading compare to the SS-2 reading.

[STATUS]

Cmon play nice..

Lets discuss that actuator stopper, I think its fine. if the actuator was fully open all the time there would be no boost. The same as if it was to hit target boost and sit fully open boost would fall off.

The wastegate flap is constantly regulating at a high rate, and would hardly be open fully to hold target boost, if even open for longer than countable seconds at a time. Therefore I see the wastegate stopper as a means to prevent sudden changes in pressure. The actuator could be reacting too slow as the revs rise and with an obvious increase in manifold pressure I can see how the flap would be pushed open too far and cause it to drop boost.

The issue of pressure in the manifold should be something that could be worked out mathematically AFAIK. We are talking CFM in and CFM out after all.... considering flow = power more or less, as long as the turbine can flow the gas through it at those shaft speeds, I dont think there could be a problem.

Id leave that for Stao to answer tho, he is the one who quote engineers these turbos.

i think you got me mixed up, i send ALOT of customers to stao for budget turbos.

These are prototype turbos and my issue is not with his turbos in general, i was just explaining i dont like the idea of using a band aid fix which forces gas through the turbine side of the turbo. The stopper limits the amount the actuator can open which in turn forces it through the turbine this sky rockets heat and has been known to damage the turbos turbine and more worrying exhaust valves over time.

[hypergear]

Those stopper part no longer exist. I've found out more effective ways to archive better results.

But in another hand. If I run 24psi out of .63 turbine with a high pressured external gate, won't I be expecting the same sort of heat and back pressure problems? considering the amount of air bleed out through the external gate is equivalent to the amount taken out by “limited flow” internal gate keeping up with inlet manifold pressure requirements?

[SimonR32]

But in another hand. If I run 24psi out of .63 turbine with a high pressured external gate, won't I be expecting the same sort of heat and back pressure problems? considering the amount of air bleed out through the external gate is equivalent to the amount taken out by “limited flow” internal gate keeping up with inlet manifold pressure requirements?

Similar to the point I was trying to make

[GTScotT]

Similar to the point I was trying to make

pretty similar to what im speculating also

[jjman]

Digging up an old thread here but im searching my balls off here for the last few months and even touching base with turbo technicians and builders n still cant seem to nut this one out.

Essentially im still trying to decide on this .64 v .86 issue as well as the overall turbo.

Basically i want as good a turbo response as possible on my RB25DET (R33)- while room for a bit more up top. Iv currently got the stock turbo maxxed at 1bar (14.7psi) which of course drops to 12psi at redline. It is pushed hard and has 300hp atw and is a dream to drive. Obviosuly it wont last forever (or long for that matter, but its been over 12 months now n no probs) so im sorting the upgrade before the turbo lets go, also id like to back the tune off a bit as its pushed pretty hard to go like it does right now.

At the moment im looking at the Garrett GT2871R with a .64 rear housing (in a 6 bolt t3 so it goes straight in housing-wise to my R33). From all i can ascertain this is the turbo that is the basis for the RB25 HKS GTRS

This would include either a 50mm compressor with 48trim, or 54mm compressor wheel with 56trim (tho this will perhaps be a bit laggy and run into surge?)

In theory this should retain near stock responsiveness and deliver another 5-10% power up top (perhaps see 15psi to redline).

anybody care to give me some info on this as every builder/tuner seems to have their own niche that they dont want to think out of. e.g. several that wont think anything less than GT30 tho ive driven these and for the street is not my cup of tea.

im not fussed about the boost dropping off in the higher revs. I just want great response for a great street car (without shelling out massive $ for a HKS GTRS or 2535)

comments from people who know and even better from people who have done it??...

Edited June 21, 2011 by jjman

[simpletool]

The T25 turbine isn't the right shape for the T3 rear housing. You can match the exducer size but typically it doesn't work so well (from what I have READ...no experience here). You want the T25 housing matched to the T3 footprint - which the HKS housing GTRS has and that is what makes it sooo good. They typically make 240rwkw when setup correctly. With 1 bar at 3200rpm or so and will hold almost entirely to redline.

A 0.86 housing will make more torque, a 0.64 housing will make torque earlier but won't support that size compressor. If I did it I'd get the T3 > T28 adapter (and machine it to fit the flanges well) and use a 0.86 T28 housing and the 56 trim compressor. It'll prob make the same power.

...............but it won't be as responsive as the genuine RB-specific GTRS.

Edited June 21, 2011 by simpletool

[hypergear]

If you run standard T2x turbine in generic T3x flow tunnel it won't perform. But if you turn it other way around it works out ok. How ever turbine housing must be specifically made and modified to suit. If every thing is engineered correctly you can get 2530's response with 3071's torque and power (Ie. SS-1 combination):

http://www.skylinesaustralia.com/forums/index.php?showtopic=55845&view=findpost&p=5715683

[R31Nismoid]

I hope you realise that if your turbo lets go, and the compressor wheel disintegrates... You could potentially destroy your motor?

Running that much boost it quite a risky decision if you don't intend to rebuild as it has happened before in a few instances to users on this forum. Big gamble for the sake of 3-4psi and 15rwkw or so.

So with that out the way if you want the most responsive it's gotta be HKS2530 style, but limited to power.

Is there a power goal or is it simply response is the ONLY desire?

[hypergear]

That turbo is very specifically engineered with lot of parts beefed up and custom made. Turbo won't let go unless engine goes. Generally you would run 18psi of stock engine making around 250~260ish. But the response is there.

You can call it T3x based CHRA working with none standard .64 rear housing.

Back on the topic, if you are going to use a 2871 you might want to modify your stock setup to suit its original .64 rear housing for the best result.

[R31Nismoid]

I was talking about his stock turbo @ 14.7psi which is beyond risky when it can kill a motor in half a second.

[hypergear]

My apologies I miss referred your reply. I think that’s the reasons of why they made later versions out of plastic. So the materials are unlikely to do too much damage to the motor once sucked in.

[jjman]

I was talking about his stock turbo @ 14.7psi which is beyond risky when it can kill a motor in half a second.

yeah did my homework before i did this. I have the series 1 turbo with the alloy compressor wheel which I could not find any evidence of it letting go. I only found evidence of the plastic/composite Series 2 compressor wheels letting go in the fashion you highlight and destroying motors.

the ceramic exhaust wheel is another matter of course but doesnt end up in the motor requiring a rebuild.

[jjman]

The T25 turbine isn't the right shape for the T3 rear housing. You can match the exducer size but typically it doesn't work so well (from what I have READ...no experience here). You want the T25 housing matched to the T3 footprint - which the HKS housing GTRS has and that is what makes it sooo good. They typically make 240rwkw when setup correctly. With 1 bar at 3200rpm or so and will hold almost entirely to redline.

A 0.86 housing will make more torque, a 0.64 housing will make torque earlier but won't support that size compressor. If I did it I'd get the T3 > T28 adapter (and machine it to fit the flanges well) and use a 0.86 T28 housing and the 56 trim compressor. It'll prob make the same power.

...............but it won't be as responsive as the genuine RB-specific GTRS.

If you run standard T2x turbine in generic T3x flow tunnel it won't perform. But if you turn it other way around it works out ok. How ever turbine housing must be specifically made and modified to suit. If every thing is engineered correctly you can get 2530's response with 3071's torque and power:

http://www.skylinesa...dpost&p=5715683

thanks heeeeaaaps for that guys. This is the piece of the puzzle i think i was missing in making sense of all the contrary opinions on how these would perform- the whole t2x t3x housing and how it affects the flow based on what the turbine was setup to do. I always thought that it was really just to do with the flange design to the manifold and otherwise it was the size that counts (oh yeah, i went there). Turns out its more technical then...

hahahaha, this makes more sense for the GTRS then. It really is like an ultra hot chick that performs in every sense but will only come to the party if you blow copious amounts of money on her. You can spend less but you wont be getting the same...

hmmm, back to the drawing board then.

Unless, stao. Can you theorise how either of these 2871r turbo's with .64 or .84 t3 rears would perform? will it still go pretty well or is it just going to be an ugly turbo combination that will dissapoint? which I guess is a pretty redundant question based on the above statement on the GTRS- which is a .64 rear housing...

otherwise, the HKS 2535 might be a good bet?. One is up for sale on here second hand so maybe that is the best option right now (no matter what im not spending money for a HKS GTRS)

Edited June 21, 2011 by jjman

[hypergear]

If you run 2871R in original .64 rear housing it should perform ok. But if you install it into a T3x .63 or .82 housing it still works but won't perform as well. .86 T2x rear housing will add lag, but not so much in power or torque. the HKS 253x housings are T3x housings with T2x flow tunnels made for an easier Bolton option.

[discopotato03]

The other option is to track down an OP6 Hitachi turbine housing and have it machined to suit your turbine .

Your calls but IMO you cannot compare a 0.64 and 0.86 AR GT28 turbine housing in the same way you'd compare 0.63 and 0.82 AR GT30 turbine housings . The difference with the GT28 housings flow wise is not as great as with GT30 housings even though the AR numbers are similar .

Like I said earlier the 0.86 GT28 housing still brought my GT2860RS up reasonably early on my old FJ20ET .

I wouldn't hesitate to use a real T3 flanged GT28 0.86 AR turbine housing on an RB25 if such a thing existed , sadly they don't and I think the closest thing is the OP6 turbine housing of Z32 single turbo VG30 four cam engines and some R34 GTt turbos .

A .

[jjman]

HKS it is- 2535

iv always liked the damn hot girls so i might as well apply my rule here too