Top End Boost Drop On Gt2530 Equipped Rb20

[reNEGaDe88]

Is the turbo just not running out of puff at high rpm cos its a tiny turbo? Good for mid range

[abu]

Any updates?

[femno]

Not yet, will most likely have results Wednesday.

[Fat_Tony]

My 2530 goes from 16psi to 12.5psi at the top. Got an EBC, but have a very quiet restrictive exhaust.

Even so, I think the turbo is just too small for top end power. Gives excellent response and mid-range.

[Russman]

No matter what we tried with the AVC-R we coun't get the wastegate to close at high revs. So we've still got drop at about 6500-7000 back down to about 16psi. It hits hard with about 20psi with exellent mid range though. I'll just have to learn to shift at 7000. Bit hard when I'm used to hitting it at 7900-8000 all the time!

We made just over 230rwkw's now so thats a 30kw gain from what I had at 14 psi. It pulls very hard now!

[Equinox]

Did you watch the wastegate on the dyno though? Is it actually open at 7000+ rpm?

[Russman]

Yeah it stayed open.

[Roy]

I think you will find there is so much back pressure at that boost level you need a monster spring to keep that bad boy closed. 230rwkws is a SHITLOAD of air and therefore back pressure in the that little housing whish will be jamming that wastegate open...

LOL or at least that the theory of these armchair critic

[femno]

Yeah nar youre right Troy, no matter what we did it remained open.

Another thing we noted is that as soon as the boost started to drop, the manifold started glowing slighty. Its being strangled....the turbs just isnt big enough.

230 is a pretty good number from that turbo...Russ is happy to sit on that for the moment.

Turbo or Engine upgrade Russ?

P.S Troy are you still going to Superlap? I cant see your name on the list anymore. (Maybe just blind)

[Roy]

Nah mate, i am stranded in Hyderabad, India. Car is still in pieces too

Surely the Garret geeks out there no of a larger housing that can go on the 2530? \ But in the back of my head i am thinking a 2530 with a bigger hot side will help extend the top end. Whether extrude honing and parting the gate flap is all band aids i dont know. Perhaps its easier to jsut go 2535, but then you have the larger compressor to overcome...i

[R31 POWER]

Strange. Maybe the hks gt2535 is just that little bit bigger. Mine holds 19/20psi to redline (7400) Once i get a better dump and coils it will be getting a retune with as much boost it will swallow.

[Equinox]

The HKS GT2535 is a fair bit bigger. Almost the size of the HKS GT-RS. 69mm vs the GT2530's 60mm.

They all share the same turbine however.

Edited March 26, 2009 by Equinox

[STATUS]

Hey guys,

Got a quick question.

We were on the dyno the other night with my mates 32, we upped the boost from 1.1bar (strong, flatline 1.1 with no dropoff) to 1.4bar had a nice increase in torque and power (around 220kw) but, after boost ramps up nicely to 1.4, it slowly drops all the way to 1.1 by redline. Its as if the turbo is running out of puff.

Currently running a HKS 2530 63T with 0.64 housing, Tomei 260 cams (timing unknown at this point, but EX looks to be retarded for nice midrange judging by the CAS), HKS Adjustable actuator adjusted to achieve 1.4 bar with no bleed off, PowerFC. We previously had a mech bleed valve with actautor set to 1bar, did the same thing.

After viewing plenty of RB20 dyno sheets it seems common that people have boost drop across the revrange, so im betting on an EBC but just thought id get some input cos theyre not exactly cheap.

Must we run a EBC to control the boost? Im doubting it but could it be the cam timing affecting the boost so dramatically? Should we '0' the cams? Theyre the only other thing untouched.

Cheers!

Mat.

common as hell on the GT2530, ive even gone to the trouble of fitting diff boost controllers and all taper off.

[Equinox]

Nah mate, i am stranded in Hyderabad, India. Car is still in pieces too

Surely the Garret geeks out there no of a larger housing that can go on the 2530? \ But in the back of my head i am thinking a 2530 with a bigger hot side will help extend the top end. Whether extrude honing and parting the gate flap is all band aids i dont know. Perhaps its easier to jsut go 2535, but then you have the larger compressor to overcome...i

Roy.

The HKS GT2530, GT2535 and GT-RS all run the same NS111 turbine and the same turbine housing. If it’s big enough for the GT-RS then surely it’s big enough for the GT2530. I think the problem lies in the compressor.

[femno]

So if we wish to maintain the hard midrange hit and grab a bit more power up top, what to do? Would hi-flowing the 2530 achieve this/be possible?

Or have a slightly bigger comp and wheel combo fitted?

This only needs the slightest upgrade...

[Equinox]

I’m in the exact same position with my SR20. I have a GT2860RS (GT2530 equiv.) and the midrange is amazing. Hits 19psi at 3000rpm, but it trails off to 15psi up at 7500rpm. It only needs the slightest bit more on the compressor side to give it that 3lb/min or so more flow up top. The problem is the next step up from the Garrett GT range is the GT2871R (GT-RS) and that’s too large for a 2L running only 18psi. There’s no middle ground.

I'm sure someone has found a custom setup for this situation. Hopefully someone sees this thread who is more knowledgeable about available turbos. *cough* discopotato03 *cough*

Edited March 26, 2009 by Equinox

[THENIG]

Here are 2 dyno graphs after tuning, first is with RB20, second is after rb25 conversion.

rb20 had gtr injectors, rb25 are stock, other than that both had same mods.

HKS2530 KAI kit (unsure which comp. housing it is but im guessing the most common one)

standard hks wastegate

Z32 AFM

FMIC (small, xr6 core)

hks dump into 3.5" lower dump pipe, into 5" stainless cat into 3.5" quiet TRUST exhaust

turbotech mech. boost controller

remap rb20 computer (no VCT controller on rb25)

standard airbox with paper filter

denso fuel pump (1JZ or 2JZ)

i am getting major boost drop after the conversion in the top end, i think it is a comination of problems, maybe a boost leak somewhere or maybe too much restriction on the induction side.

Edited April 1, 2009 by THENIG

[femno]

Well if you actually read the whole thread you would find that what has been discussed is that the 2530 is too small for the RB20 to achieve good top end boost.

What makes you think it will be any better with an extra half a litre to flow?

So any ideas on how we can modify the turbo to flow that little extra?

[wolverine]

possibly extrude honing the covers will give you a little extra but it would cost around $250 per cover plus the cost of removing it all.

if you only do the turbine cover it might work out ok but it would be an expensive exercise if it didn't achieve what you wanted.

[Equinox]

The compressor wheel needs upgrading to support the larger flow, however the only step up from the 63T 60mm compressor on the GT2530 is the 48T 71mm compressor from the GT2871R which is a bit too large for an RB20. (Would be great on an RB25 though)

Do Garrett have a catalogue of wheels somewhere?