Gcg Turbo Specs

[Jolinator]

i sent them this, and got the following reply, which i found a bit hard to beleive given were talking bigger wheels, and non ceramic.

Thanks for the enquiry. Answers to your questions are below:

is there a Difference using an rb20 or r25 turbos, given the 25 has a bigger exhuast housing?

No other differences at all.

do you offer anything slightly smaller in the way of highflows, im looking to make 210rwkw, max, on an rb20det, in a 32 gtst, my only concern is if i can get something smaller than what you offer as standard, with the rb20 being down in the torque department i need something that spins up as early as possible,

The high flow will come on boost, and respond exactly the same as a standard turbocharger, but make more power, so there is no need to worry about response with the RB20det.

Kind Regards

Michael Ramsay

[jazza08]

Id say you wouldn't get TOO much more lag on an rb25 with a standard turbo upgraded to the gcg hi-flow, however on an rb20 it would be similar to puttin an rb25 turbo on (more lag more power), but maybe not too much more laggy than a standard rb25 turbo on an rb20 if you get what im trying to say?

Its common ppl saying you won't notice any loss in responce so don't think he's trying to pull your leg but you will get atleast 1000rpm more lag for full boost from what ive heard/seen. Rb20 standard turbo wit supporting mods = 1bar @ 3000rpm, gcg hi-flow = 1bar @ 4000rpm (approx wit supportin mods obviously)

[Abo Bob]

I get 1 bar at 3200 with my highflow. It spools like stock so where I previously had 2-3psi I still have 2-3psi, where I had 12psi I still have 12psi.

I was going to say it's only a little laggier but then I compared all my old dyno sheets and was surprised to see them boosting at the same level at the same rpm.

[discopotato03]

Not hard to work out really , the RB20 and 25 std turbos Ive seen use different sized turbine housings so if they modify what was the RB20 version the gas speed will be higher than with the RB25's housing .

Cheers .

[chrissso]

Here's a diagram of what I interpreted from discos other post...

[chrissso]

Im on 7 lbs at about 2200rpm - stock turbo. 11 pounds is about 2500.

I would expect that to jump up another 1000rpm. Thats the same lag as an sr20det - pretty reasonable.

I get 1 bar at 3200 with my highflow. It spools like stock so where I previously had 2-3psi I still have 2-3psi, where I had 12psi I still have 12psi.

I was going to say it's only a little laggier but then I compared all my old dyno sheets and was surprised to see them boosting at the same level at the same rpm.

[Sydneykid]

Im on 7 lbs at about 2200rpm - stock turbo. 11 pounds is about 2500.

I would expect that to jump up another 1000rpm. Thats the same lag as an sr20det - pretty reasonable.

With the GCG ball bearing high flowed RB25DET turbo on the RB20DET we see 1 bar at 3,000 rpm in 3rd, 4th or 5th gear. And it will rev happily to 8,000 rpm. It sure as hell doesn’t feel laggy.

There is a lot in how it is tuned and how good the boost controller is at keeping the wastegate firmly shut.

Off boost, it’s a 2 litre engine with 8.5 to compression ratio and 180,000 k’s on it. I don’t expect the same torque as a fresh RB31DET with 9 to 1 compression ratio.

cheers

[jazza08]

show off

As you can tell by Gary's responce tuning can make the world of difference

[chrissso]

With the GCG ball bearing high flowed RB25DET turbo on the RB20DET we see 1 bar at 3,000 rpm in 3rd, 4th or 5th gear. And it will rev happily to 8,000 rpm. It sure as hell doesn't feel laggy.

cheers

Wow. That's good!m Why is it so good? Cams?

I didn't mean to imply that it was a little laggy. By saying pretty reasonable, I meant, well, great.

[Bass Junky]

hmmmm

I don't see full boost until more like 4000 rpm or later sometimes.

I have a rattle in the exhaust at idle and AlexCim told me he had the same rattle and it was a loose wastegate actuator allowing the wastegate flap to rattle. Hence it was open at low boost levels, hence he had long spooling times. He also had the same GCG highflow.

Mine sounds the same he said.

Maybe I need to pull my bloody inlet tract apart and play with that wastegate.

Maybe I'll be boostin much earlier.

SK, ever heard of a GCG having this problem?

[JD-33]

Hey all,

am planning to get my rb25 turbo hi flowed soon..

are GCG the best ppl to go with? ... what other places are there out there (which you recommend) to get a turbo high flowed?

On average how much kw increase can you expect from a high flowed turbo?? (i.e. dyno with standard turbo, get it high flowed, then dyno with hi-flowed turbo)

Cheers,

-JD

[Dale FZ1]

GCG offer a rebuild using the stock core - retains OEM oil and water lines. Makes it a straight bolt-in proposition, and has a very good reputation for achieving results.

Other suppliers tend to use a complete Garrett cartridge and mate up the stock comp/turbine covers. Also very good, but requires custom oil/water.

The upside to going this way (perhaps) is that if you do lots (and lots) of reading/research you can opt for a turbo that is built to your spec. Costs tend to even out however.

cheers

[Bass Junky]

Well Holy Crap Sticks Batman.

Remember I told you about my rattling exhaust and stuff?

Well....

I just "ghetto" modified my waste gate actuator shaft.

I driled another hole in the wastegate shaft just to the left of the standard hole. Took me a while to get the shaft back onto the waste know, but we got there in the end.

Drove the car and holy hell, the response is magnificent. I now have full boost in every bloody gear by 3000 rpm!!!!!

The thing is a bloody boost monster!

coming onto boost in 2nd now results in wheelspin and massive pushing back into seat antics.

BUT, and this is a big but.

The MASSIVE preload I have put on the shaft now means the power FC calls no joy when the boost spikes as it comes on, even with with like 20 in the gains on the boost controller setting.

I get to 4000rpm, and the thing just goes start/stop in a split second makes my guts hurt.

So, tomorrow I will be re-modify the shaft buy heating it, bending it and only giving it a smaller amount of preload but still enough to keep away that bloody rattle and keep the thing closed and boosting.

I simply cannot believe the difference. The thing is a total animal now!

BRING ON DECA BABY!

[Bass Junky]

Bass is giggling like a little school girl.

How much preload in mm is enough....

right now I have like 10mm which is obviously too much.....

[Abo Bob]

Hmm, gotta pull my turbo off soon to check it out so might do this at the same time.

[R31Nismoid]

Nice work Pete.

yours wasnt "un-responsive" in my book, but if its coming on nearly 1000rpm earlier and better... thats just even more ammunition for the GCG hi-flow being a spot on upgrade for a street RB25DET

[paulr33]

good stuff, well done. yeah the pfc boost kit has boost cut if it spikes over 0.25kgcm2 above the desired pressure level

[Bass Junky]

I had a play this morning.

I sete the desired boost on the PFC to 1.2 bar.

Car pulled hard as a rock, boost levelled out and away she went.

Crikey it's quick now.

Shame I can't use it on the road though.

DECA HERE WE COME

My rear tyres are shaking in their boots!

[Abo Bob]

I thought you got detonation above 1 bar? Be careful mate!

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