GT2530 - Not impressed

[Cubes]

Yer sorry I meant to say 1.1bar...

Doughboy.. There is definately lots of potential left in that turbo if you can get the boost drop sorted.

[R32 Zilla]

I run a genuine HKS GT 2535 on my r32 rb20.

At a recent dyno day it made 206 rwkw at 19psi which is about 5 to 10 down on what i think it should make. The dyno used has a name for running slightly lower figures than most in sydney.

comp housing is .60

exhaust housing is .64

using matching split dump pipe

10 psi at 4000rpm (ABOUT) have to check tomorrow

19 psi at 4500rpm (ABOUT) have to check tomorrow

A bit laggy but great fun !

Tim.

[Merli]

Originally posted by JimX

I'm glad you said that. I'd never really thought about it much before, but I used to think that if you set the boost to higher than factory, it would get there faster. But after pulling my turbo off and having a look inside, it seems that the waste gate stays completely shut until the set boost is reached, and then it opens.  

That would mean it gets to a certain pressure level at the exact same time no matter what you set it to. It would just not go higher than the boost controller allows.

This would explain why I don't hit "full boost" until 4500-5000rpm. I've got the turbo set to 1 bar, so I don't think it's as bad as I first though. If it were set to factory pressures, it would probably get to "full boost" at around 3500.

It's late, and I'm tired, so perhaps I didn't quite understand that properly, but it seemed to me you contradicted yourself a few times in that post :confused:

Basically, in theory, the turbo spools up by exhaust gasses spinning the shaft... The more it spins the shaft, the more air the turbo will pump into the engine, and the more air will exit the engine, turning the turbo faster, in turn forcing more air into the engine, etc ,etc etc... As you can see, it's an exponential rise in power gain, which is theoretically limitless. Of course the size of the turbo and efficiency deems that incorrect, but you get the idea.

Now since we have an exponential curve, that means we need to limit the power somewhere along the line so we don't blow up our engines. In comes the wastegate. Basically all the wastegate should do, is wait until you have reached the desired boost pressure, then open up and let the EXCESS exhaust gasses bypass hitting the turbine wheel, prohibiting it to spin faster and making more boost. Pretty simple design. (Pity about wastegate creep )

So back to our exponential curve. The actual shaft speed is exponential, and hence the boost curve is exponential... This means that as you continue to spool up the turbo, the more boost your turbo is making, the faster the boost will increase.

e.g. At 0.1 bar, it would take 2 seconds to hit 0.6 bar

but at 1.2 bar, it would take only 0.5 seconds to make the same 0.5 bar increase to 1.7 bar.

Makes sense? Basically as you build boost, it will build it faster and faster as you go along (exponential curve).

Phew. So back to your original comments about boost, you're absolutely correct.

If you set your boost controller to 0.5 bar, it would take say 2 seconds to hit 0.5 bar.

If you set your boost controller to 1.5 bar, it would STILL take 2 seconds to hit 0.5 bar, and an ADDITIONAL 2 seconds to hit 1.5 bar... (Completely arbitrary values, but you get the idea I hope)...

You know what, I don't even know why I'm posting this. After re-reading what you wrote, I realise you already know all this. Oh well, I sure ain't gonna delete it, so I'm just gonna press the "Submit Reply" button now.

[DoughBoy]

But but but...

What if the flow of air (lbs/o2) runs off the x axis or goes above the surge line to obtain that 1.5 bar?

Will it take longer to get that 1.5 bar or just nevah happen?

Hehe just threw that in to see what reaction it would get from your tired state!

[JimX]

Originally posted by Merli

You know what, I don't even know why I'm posting this. After re-reading what you wrote, I realise you already know all this. Oh well, I sure ain't gonna delete it, so I'm just gonna press the "Submit Reply" button now.

Well, I didn't "know" all this, but it was pretty much what I had worked out in my little brain after I pulled my turbo off and had a good long think about it. It's good to see that I had the right idea about it all, so I'm glad you posted it!

I'm still not sure where I contradicted myself in my post though. If you can let me know where I went wrong, I would appreciate it.

[TokyoTaxi]

I spoke to Garrett directly yesterday and they assure me that they CAN supply a GT2530 core assembly equal to that of HKS.

So maybe I have the right core but using the R34 GT-T compressor and exhaust housings might be the problem.

Yesterday out at the Creek the turbo was reaching 1.4bar but once the engine spooled over 6,500rpm the boost dropped below 1bar and by about 7,500rpm it was at about 0.85bar and the engine was screaming like an N/A engine.

Is that along the lines of what anyone else is experiencing using a "real" GT2530 on an RB20DET ?

[EVOIV]

Yes, Garrett can supply the "core" of the HKS GT2530, but I am pretty sure that they can not replicate the HKS GT2530 turbo. Meaning that they can't provide you the HKS specific compressor trims. I believe that the turbine trims for HKS and Garrett are the same, it's just the compressor trims that are different. Or maybe I'm wrong? Are HKS turbine trims different too?

[Roy]

FAT32, your car is black??? I was wanting to have a look at your car but didnt see you in the pits.

[Steve]

Real HKS 2530 on rb20 - pulled at 1.2 bar to 8200rpm redline.

If they say it is equal - they are just being pedantic, equal in what way? What are the trims/wheels size etc. I am quite sure they may say it is equal (which could mean it is rated at the same peak hp - and nothing more another example would be to say that a VG30 is equal to a RB26 because they put out the same power, not telling a lie, but not the whole story either if you get what I mean). HKS would love to know that garrett are selling their design turbo to the rest of the world - would be in breach of agreement and leave them wide open to be sued?

Ask the guy how exactly it is equal, and how it doesnt breech the agreement with HKS if it is equal - might throw a bit more light on the subject, even better, ask him for it in writing or e-mail - then forward it to HKS and see what they say:D

[TokyoTaxi]

Originally posted by Roy

FAT32, your car is black???  I was wanting to have a look at your car but didnt see you in the pits.

Yep that was me driving around the track swearing at my turbo the whole way ! I met you in the pits but I was in the garage with the drift monaro's ( my friends ) waaaaay down the other end.

[TokyoTaxi]

Originally posted by Steve

Real HKS 2530 on rb20 - pulled at 1.2 bar to 8200rpm redline.

If they say it is equal - they are just being pedantic, equal in what way?  What are the trims/wheels size etc.  I am quite sure they may say it is equal (which could mean it is rated at the same peak hp - and nothing more another example would be to say that a VG30 is equal to a RB26 because they put out the same power, not telling a lie, but not the whole story either if you get what I mean).  HKS would love to know that garrett are selling their design turbo to the rest of the world - would be in breach of agreement and leave them wide open to be sued?

Ask the guy how exactly it is equal, and how it doesnt breech the agreement with HKS if it is equal - might throw a bit more light on the subject, even better, ask him for it in writing or e-mail - then forward it to HKS and see what they say:D

Not gunna stir up mountains of sh!t. I just want to fix my turbo problems and know what's going on for a change with regards to what I've got and what I need and what I have to do to get it and fit it. :uh-huh:

[Steve]

FAT32, sorry for the digression in your thread - bloody thread whores:)

I did a bit of research about HKS turbos, specifically the 2530 and it appears the only bits that are stock garret are the cartridge and the turbine wheel. The compressor wheel and housing and the turbine housing are HKS only items, that probably explains why they are stamped with HKS

Getting back to it - I know this isnt the best answer, but one option may be to see if you can buy a clagged HKS 2530 for a few hundred dollars and swap the cartridge from your turbo, then sell the compressor housing and wheel and the turbine cover?

May not be the most realistic answer, unless you know of a clagged 2530 going cheap?

[R32 Zilla]

Checked my psi at rpm figures today, they are

10psi at 3700 rpm

18 psi at 4400 rpm

All done in in 3rd gear.

Tim.

[DoughBoy]

Uh FAT32, if I had known you were at EC I would have suggested having a ride in each others cars just to see the diff between a Garrett 25/30 and a HKS 2530. Would have been interesting.

[TokyoTaxi]

Japsix,

Thanks for those stats. I'll check mine now.

Steve, That's an idea that's already crossed my mind

DoughBoy, I saw quite a few people out at the Creek but would have liked to meet more / all. Nissky came out for a ride with me and he can attest to the fact that my turbo was a dog on the day, HOWEVER, over the weekend, I found that the gasket on the outlet side of the turbo was cracked and it looks like pressure was leaking out. I fixed it and drove the car down to get the front pipe & dump pipe fitted and then took the car out for a quick blat and the boost climbed to 22psi and lit up the rears ! Since I didn't have much time after that I put it back in the shed and I'll re-investigate this issue further. Maybe the problem ain't so bad after all

[nissky]

yeh your car was slow ;p

do you want to swap turbos?

my boost controller stopped working after the second session, so i was running 7psi for the rest of the day , stupid r34 actuator!

i hope you fixed and it was just a leak, i want a real ride :burnout: next time

[rev210]

Originally posted by FAT32

Yesterday out at the Creek the turbo was reaching 1.4bar but once the engine spooled over 6,500rpm the boost dropped below 1bar and by about 7,500rpm it was at about 0.85bar and the engine was screaming like an N/A engine.

Is that along the lines of what anyone else is experiencing using a "real" GT2530 on an RB20DET ?

sounds like the wastegate actuator is still the stock unit. Get yourself one with a heavier spring thats rated to your desired boost level.

[Guest turbogtst]

Why would someone put a GT2530 on a rb25 when you need two for an a rb26, they are way to small, those idiots at GCG should not have sold you that turbo, t3/t4 is the only way to if you want to make some real kw's

[DoughBoy]

Originally posted by turbogtst

Why would someone put a GT2530 on a rb25 when you need two for an a rb26, they are way to small, those idiots at GCG should not have sold you that turbo, t3/t4 is the only way to if you want to make some real kw's

Depends on application and personal tastes. I don't think that a GT2530 is too small for an RB25, great response and nearly feels like a naturally aspirated motor.

[Cubes]

Originally posted by turbogtst

Why would someone put a GT2530 on a rb25 when you need two for an a rb26, they are way to small, those idiots at GCG should not have sold you that turbo, t3/t4 is the only way to if you want to make some real kw's

They didn't put a GT2530 on a RB25. It was a RB20.