What Turbo To Match 0.86 Pro S Housing

[grepin]

I have a spare 0.86 Pro S exh housing that I am considering matching a turbo to.

My current 2835 ProS on RB 25 is running out of puff and need something with a larger compressor.

I am considering fitting up either a GT30/35 turbo to it.

What are peoples thoughts. I am currently making 300rwkw but the turbo is working hard and dropping boost badly up top. Pobably producing suerheated air. I basically have a GTR head and heaps of flow.

Does anyone recommend any workshops. GCG is one that comes to mind.

Edited June 11, 2006 by grepin

[T04GTR]

that little turbine wheel would be choking pretty hard.

from my memory it is 2.22/2.11 inch dimensions 90trim

one problem with the nice gt series turbos is the dont benifit to much from "high flowing" but rather exhaust housing changes.

im sure discopotato sp? woulkd agree with me here.

i was gonna get a gt35-66 (with the 63trim (66.7mm comp wheel) but i was talked out of it from my turbo suplier as the did a back to back test on a 13b turbo with a gt35r then a gt35-66 and lost 30hp at the wheels. with a backpressure gauge the 66 wheel was out flowing? the turbine wheels capabilities chocking the motor.

336rwkw to 314rwkw on the same boost. 1.2bar with the 1.06 rear housing

[Cubes]

What boost are you running Grepin,

I remember a few years ago Steve was running a HKS GT3037S on his RB25 with real mild cams & headgasket to drop comp down to 8.6:1. That made 323rwkw on 23psi. Hrmm thats testing me.. I'm 99% sure it was 23psi.

He was running the PowerFC ebc and said it held boost perfectly.

So what you want to do is have the 2835pros turbine housing machined up to suit say a gt30/40 or something similiar?

If thats the case it may be worth seeing what you can get for your pros turbine housing and buying in a 3037pros turbine housing from the states. Then drop it on the rear of a gt3040 and have just that little bit more compressor flow. If it would work better in practice than a similiar hks spec'd gt3037 is questionable. How the 3037s works so well with its compressor is beyond me as on paper it doesn't flow all that much compared to the 76mm gt30 comp wheel.

[T04GTR]

or do what cubes said.

[grepin]

What boost are you running Grepin,

I remember a few years ago Steve was running a HKS GT3037S on his RB25 with real mild cams & headgasket to drop comp down to 8.6:1. That made 323rwkw on 23psi. Hrmm thats testing me.. I'm 99% sure it was 23psi.

He was running the PowerFC ebc and said it held boost perfectly.

Running 21 psi which drops off to 15 psi up top. I have tried everything from heavy actuators, extra springs, dual actuators but the wastegate gets pushed open. Dont get me wrong I make heaps of power with it. Probably beyond its potential. I even bolted up a 0.86 exh housing thinking more flow but still does it. I lost some mid range but got 320rwkw.

Now I have the extra housing I am thinking I could sell off the 2835 match up a turbo to the extra housing which matches my dump etc.

Pobably considering the GT35 turbo with the HKS housing. It may need machining however maybe.

[Cubes]

Hows it spool now as R31Nismoid ran a GT3040 .82 and it was coming on strong around 4k.

Is that what you want?

Clint32 made 338rwkw and 580hp on the engine dyno with a GT3040 .82 That was running some where in the mid 20psi range, big cams, plenum, motec all the good bits. I believe Morpowa tuned it.

The GT2835ProS runs the same comp wheel but smaller turbine.

I wonder if it drops boost due to the lack of shaft torque required to drive the big gt40 82mm comp wheel.

I think the next step is a GT35R. But with that comes lag, on the rb25 I believe they get going around 4.5k.

On the RB30 the .82 GT35R feels suprisingly nice, comes on strong from 3500rpm+.

Maybe something to look at one day if you really want to start nudging 400rwkw.

Pair the rb30 up with with a oil pump crank drive collar and nice aftermarket balancer and they have no issues reving reliably.

Or as one of the blokes has done here (and I believe he's in Adelaide too) used an rb26 block. rb26 rods, custom pistons, destroked rb30 crank for 2.9ltrs. So no block height issues or engine number problems.

[discopotato03]

Grepin a couple of cause and effect issues here and some unit number information for others .

It looks like you've run your GT2835 Pro S beyond what its designed to cope with air and exhaust flow wise . High turbine inlet pressure is what's forcing your integral waste gate flat valve open . Wastegates are generally regulated by boost pressure so if you factor this plus the actuator spring rate and lever ratios of the linkage + arm the turbine inlet or exhaust manifold backpressure if you like must be pretty high .

From the HKS spec sheet I have it seems the 2835 Pro in RB20/25 version ie having the T3 flanged turbine housing uses that cropped GT30 turbine ie 56.6mm diametre in 84 trim only . It shows the T28 flanged version (bored out .86 AR ratio GT28 turbine housing) as using the 90 trim version of the cropped 56.6mm turbine .

Also the GT Pro 2835 uses the largest trim version of the GT35 compressor ie 71mm 56 trim .

I should start from the base line with the 2835 series turbos or it gets confusing .

They are offered in five versions and four power ratings ie 380 , 400 , 410 and 420 PS . The straight 2835 can have three compressor trim options - 48 , 52 and 56 . These three have the same turbine and trim - 56.6mm 84 trim (51.8mm exducer or outlet diametre) . They can have the GT28 integral gate exhaust housing in .64 or .86 AR ratios . Or they can have the GT28 flanged external gate GT30 housings in .61 , .73 , .87 , 1.01 and 1.12 AR ratio .

The next step up is the Pro version with 84 trim turbine for T3 flanged Skylines or 90 trim for GT28 housings for SR20/CA18 etc . Remember 56 trim compressor .

Last type is the GT2835R which gets the 90 trim turbine and 56 trim compressor standard . It can have the 86 AR ratio GT28 exhaust housing or the T28 flanged GT30 housing in 61, 73 , 87 , 1.01 and 1.12 AR ratio .

Anyhow your GT Pro version probably hasn't got the 90 trim version of that turbine which is only 1.8mm larger in exducer diametre at 53.6mm .

There are a few ways you can go depending on what result you want to end up with .

I have to dash ATM but will get back on this later on , Cheers Adrian .

HKS_GT2835_Pro_S_.67_ARR_housing.bmp

[R31Nismoid]

What boost are you running Grepin,

I remember a few years ago Steve was running a HKS GT3037S on his RB25 with real mild cams & headgasket to drop comp down to 8.6:1. That made 323rwkw on 23psi. Hrmm thats testing me.. I'm 99% sure it was 23psi.

He was running the PowerFC ebc and said it held boost perfectly.

Here is the thread, solid details

http://www.skylinesaustralia.com/forums/in...=steve+3037+hks

Hows it spool now as R31Nismoid ran a GT3040 .82 and it was coming on strong around 4k.

Is that what you want?

Ye i was on around 4200rpm, that was the bigger GT30, the 600hp variant thats now residing on a car down in Tazzie

Externally gated though

It was 270rwkw - 17psi @ RacePace 98 octane, it was really quiet and it felt lazy

Then 330rwkw - 24psi @ RacePace with 104 octane, same timing as 270rwkw run... The extra few psi really really woke the car up. The fuel at this stage did ok, just stopped some misfiring.

Its hauled ass is the only was to describe it. Traction was on the limit aswell. Anymore and it would have been unstreetable

I made more power @ Auto salon, 369rwkw, same boost/fuel but with massive crank of ignition timing for the dyno run. Surprisingly not a hint of detonation either so we just wound more and more timing in till the final number.

And that was just insane, the fuel really woke the car up then with the extra timing and stuff that we played with on the day.

I drove it home and by god... great fun

Ah, RB25 memories of love

[discopotato03]

Ok , the 90 trim cropped 2835 style turbine probably won't make enough of a difference to bother with though this and or the .87AR ratio 2835 Pro S housing are the last steps for that family of turbos .

After them the next turbine/turbo family is the GT30 series meaning the full sized or 60 x 55mm 84 trim UHP turbine . They are available with 71 , 76 and 82mm compressor families (GT35 , GT37 and 82mm GT40) series compressors . Examples would be Garretts GT3071R , GT3076R and GT3040R .

If you just wanted to uncork the turbine side the GT3071R could be used as its basically the same deal but with the non cropped turbine . These will fit into the GT3037's Pro S type turbine housing .

If you want more compressor flow then the 76mm GT37 compressors can do it and probably get close to 500Hp depending on compressor trim and turbine housing AR ratio . The options are Garretts GT3076R unit no 700382-12 or HKS's GT3037 of which there is a Pro S version using the same cartridge and wheels as Garretts GT3076R - identical cartridge (CHRA) pt no 700177-7 .

Just on those Pro S exhaust housings , I'm not certain that the 2835 and 3037 versions use the same castings even though the AR ratios are the same - .68 and .87 . If you look at the outlet side of your 2835 pro housing you'll see how thin the casting is in the area between the turbines outlet and the scolloped out section venting from the wastegate flat valve . Its hard to imagine there being enough room for the 84 trim GT30 turbines 55 and a bit mm outlet to fit without "daylighting" the casting between turbine and wastegate outlet paths . If I could not be certain I'd be hesitant to machine it out for a GT30 turbine as these housings are not cheap to buy .

If your not happy with the 2835 Pro it may be a better idea to sell it complete and buy the turbo you want . The burning questions are always what mounting flange and integral or external wastegate . If you are seriously going to push the power envelope a better than std exhaust manifold is probably needed and HKS do a good one for the RB20/25 . External gates always remove the exhaust housing dramas and make it easier to get the hot side working properly - in a high power setup .

Basically the sky is the limit , only you know how much you want to spend and how incognito you want it to be . I don't think I would go beyond a 3037 Pro on the std manifold or a GT3076R (basically non gated Garrett equal) on the HKS manifold . At this stage many feel they are losing the lower mid range where its important for a street car to work well .

I wouldn't bother with a GT3040R , the large trim GT37 compressor (3076R/3037) is already beginning to overstretch the GT30 turbine so going bigger again to the 82mm GT40 I think is a step backwards . An almost 500 Hp turbine is not suited to driving a 700 + Hp compressor IMO .

Lets know what you think , Cheers A .

[grepin]

Ok , the 90 trim cropped 2835 style turbine probably won't make enough of a difference to bother with though this and or the .87AR ratio 2835 Pro S housing are the last steps for that family of turbos .

After them the next turbine/turbo family is the GT30 series meaning the full sized or 60 x 55mm 84 trim UHP turbine . They are available with 71 , 76 and 82mm compressor families (GT35 , GT37 and 82mm GT40) series compressors . Examples would be Garretts GT3071R , GT3076R and GT3040R .

If you just wanted to uncork the turbine side the GT3071R could be used as its basically the same deal but with the non cropped turbine . These will fit into the GT3037's Pro S type turbine housing .

If you want more compressor flow then the 76mm GT37 compressors can do it and probably get close to 500Hp depending on compressor trim and turbine housing AR ratio . The options are Garretts GT3076R unit no 700382-12 or HKS's GT3037 of which there is a Pro S version using the same cartridge and wheels as Garretts GT3076R - identical cartridge (CHRA) pt no 700177-7 .

Just on those Pro S exhaust housings , I'm not certain that the 2835 and 3037 versions use the same castings even though the AR ratios are the same - .68 and .87 . If you look at the outlet side of your 2835 pro housing you'll see how thin the casting is in the area between the turbines outlet and the scolloped out section venting from the wastegate flat valve . Its hard to imagine there being enough room for the 84 trim GT30 turbines 55 and a bit mm outlet to fit without "daylighting" the casting between turbine and wastegate outlet paths . If I could not be certain I'd be hesitant to machine it out for a GT30 turbine as these housings are not cheap to buy .

If your not happy with the 2835 Pro it may be a better idea to sell it complete and buy the turbo you want . The burning questions are always what mounting flange and integral or external wastegate . If you are seriously going to push the power envelope a better than std exhaust manifold is probably needed and HKS do a good one for the RB20/25 . External gates always remove the exhaust housing dramas and make it easier to get the hot side working properly - in a high power setup .

Basically the sky is the limit , only you know how much you want to spend and how incognito you want it to be . I don't think I would go beyond a 3037 Pro on the std manifold or a GT3076R (basically non gated Garrett equal) on the HKS manifold . At this stage many feel they are losing the lower mid range where its important for a street car to work well .

I wouldn't bother with a GT3040R , the large trim GT37 compressor (3076R/3037) is already beginning to overstretch the GT30 turbine so going bigger again to the 82mm GT40 I think is a step backwards . An almost 500 Hp turbine is not suited to driving a 700 + Hp compressor IMO .

Lets know what you think , Cheers A .

Certainly a bit to think about there.

I currently have an aftermarket exh manifold, Greddy plenum, Q45 thrott body, Z32 afm, 3.5 inch exh turbo back, Head with HKS GTR 256 cams bigger valves variable cam timing etc etc

Currently not keen to spend too much more money.

Just that currently I do have an extra HKS 2835 ProS housing as well as a whole turbo setup.

If I thought I could sell my turbo and make use of the extra housing for little extra dollars I would do it.

Sounds like the 2835 Pro S housing will be no good for oversizing because as you say there is no meat to the wastegate side.

At this stage I am not too keen to play around with external gate setups.

All I want to do is setup a turbo that gives me my current 300rwkw and holds boost, as cheaply as possible utilising some of what I have. To keep the current exh housing would have been good as it matches a u-bewt dump I had made with seperate wastegate side etc.

Currently having issues with high knock values as well possible due to solid lifters however may start another thread on that.

Just thinking that the turbo if starting to blow hot air may not be helping.

Edited June 12, 2006 by grepin

[discopotato03]

Often the exhaust flow ceiling is the weakest link . It may sound silly but you could try lowering the boost to a point the turbo can live with and concentrate on tuning cam timing and the ECU itself to get the most from its air and fuel . My opinion only but many power graphs look like the side of Mt Everest and while riding the boost / torque wave may seem like a good idea remember that radial compressors have a useful speed range and the more pressure you ask of it the narrower the band will be . I'd be interested to know what sort of engine revs you have when the turbo cries enough . If its short of the engines std rev limit by a fair margin I'd try less boost and more revs .

I'm only guessing but I think the 2835 series are a bit compromised by their 56.6mm turbine , I think it was done to give a bit of low to medium range response at the expense of the very top end . Its very difficult to have it both ways . This is why I keep harping about the benefits of generous turbine and housing capacity and using compressors of adequate capacity and no more . I did mention that Garretts propper GT3071R uses the largest 71mm 56 trim compressor with the full sized or 60mm GT30 turbine . Garretts long overdue T3 flanged integral gate GT30 turbine housings should be available in late July and one of these with the GT3071R should do 300Kw (400Hp) because it has the gas flow capacity on both sides of the turbo . The word is that these T3 flanged housings will be in .82AR ratio so may not thump you in the back at 2500 rpm but should be very controllable . The RB25DET's having 9.5CR (or is it 9.0) would like a turbo that doesn't boost off the starter motor and give the opportunity to screw some advance into it before the boost threshold .

I think I'd be finding out what sort of money you could turn your turbo into and what the dough could buy that worked better .

One thing I don't understand is you say you have a spare ".86 Pro S " housing , if T3 flanged it should be .68 or .87AR ratio . If its .64 or 86 it would be a T28 flanged GT28 housing .

Since you mentioned GCG I would be talking to Brett about my above suggestion . Some of the more recent GT BB turbos are going the healthy turbine medium compressor route and it can pay off if its efficient airflow your after rather than high boost numbers .

Cheers A .

[grepin]

Often the exhaust flow ceiling is the weakest link . It may sound silly but you could try lowering the boost to a point the turbo can live with and concentrate on tuning cam timing and the ECU itself to get the most from its air and fuel . My opinion only but many power graphs look like the side of Mt Everest and while riding the boost / torque wave may seem like a good idea remember that radial compressors have a useful speed range and the more pressure you ask of it the narrower the band will be . I'd be interested to know what sort of engine revs you have when the turbo cries enough . If its short of the engines std rev limit by a fair margin I'd try less boost and more revs .

I'm only guessing but I think the 2835 series are a bit compromised by their 56.6mm turbine , I think it was done to give a bit of low to medium range response at the expense of the very top end . Its very difficult to have it both ways . This is why I keep harping about the benefits of generous turbine and housing capacity and using compressors of adequate capacity and no more . I did mention that Garretts propper GT3071R uses the largest 71mm 56 trim compressor with the full sized or 60mm GT30 turbine . Garretts long overdue T3 flanged integral gate GT30 turbine housings should be available in late July and one of these with the GT3071R should do 300Kw (400Hp) because it has the gas flow capacity on both sides of the turbo . The word is that these T3 flanged housings will be in .82AR ratio so may not thump you in the back at 2500 rpm but should be very controllable . The RB25DET's having 9.5CR (or is it 9.0) would like a turbo that doesn't boost off the starter motor and give the opportunity to screw some advance into it before the boost threshold .

I think I'd be finding out what sort of money you could turn your turbo into and what the dough could buy that worked better .

One thing I don't understand is you say you have a spare ".86 Pro S " housing , if T3 flanged it should be .68 or .87AR ratio . If its .64 or 86 it would be a T28 flanged GT28 housing .

Since you mentioned GCG I would be talking to Brett about my above suggestion . Some of the more recent GT BB turbos are going the healthy turbine medium compressor route and it can pay off if its efficient airflow your after rather than high boost numbers .

Cheers A .

Correct it is 0.87 ar housing.

I can actually physically see the wastegate opening around 5000 rpm.

I have crudely measured the pressure in the housing to be 40 psi at around this point.