GCG or HKS 25** Turbo

[sweetr33]

ok and we are getting back onto the track of whether a 2530 2nd hand or a hi flow gcg item is the wiser choice when????..............................

[hoo@h]

taken from HKS japan site, might be interesting for some.

* The ball bearing which is adopted for shaft support:It decreases the friction, contributes to response rise.

* New development compressor wheel:Until recently, it is not and actualizing the compressor efficiency which is superior. Decrease of efficiency showing power little even at the time of high boost.

* New development turbine wheel:Low to be superior in operation characteristic vis-a-vis wide-ranging gas flow rate from the rotary limits to the high rotary limits, energy of the exhaust without wastefulness collection.

* Exhaust housing of HKS original design processing Circular section scroll form of advanced design. High efficiency it raises the flux of the exhaust with the microminiature housing and actualizing response rise. Large aperture tapered preventing wasteful anti- pressure rise with turbine exit form of condition.

perhaps, HKS get their turbo parts from Garrett and improve on it by their own design or it could just all be a maketing gimmick.

[knore]

ok and we are getting back onto the track of whether a 2530 2nd hand or a hi flow gcg item is the wiser choice when????..............................

For real, last time i checked this thread wasnt Garrett VS Hks

Even tho its been a good discussion

Ive said it before and ill say it again, i dont think you can go past the GCG highflow in terms of value for money and simplicity. Almost anyone can take their turbo off, send it away, and get it back brand new highflowed and wack it straight back on. Ofcourse the HKS 25xx competition will have better response and MAYBE a little more peak power, but for an extra $1000-1500 it really isnt worth it.

There has been a few GCG highflowed standard internal RB25s making on or over 250rwkw, so they certainly have no problem making the power with correct tuning and support systems. And seriously, for $1500 can u really fault it?

[Abo Bob]

$1800 but agreed with Knore.

[knore]

Well yeh ultimately it would be $1800 on the car.

I know a few people who got stage 1s from GCG for $1550

[Roy]

There has been a few GCG highflowed standard internal RB25s making on or over 250rwkw, so they certainly have no problem making the power with correct tuning and support systems. And seriously, for $1500 can u really fault it?

Not wanting to cast dispersions about GCG, more a generasl question regarding high flows. I am sometimes conerned about quality control. If we took one of these 250rwkws cars and bolted 3 exactly the same hi-flows from the same supplier on, would they all make the same power?

[Sydneykid]

Not wanting to cast dispersions about GCG, more a generasl question regarding high flows. I am sometimes conerned about quality control. If we took one of these 250rwkws cars and bolted 3 exactly the same hi-flows from the same supplier on, would they all make the same power?

Good question Roy, the cores are a Garret standard part, as are the compressor, turbine, seals and gaskets. Assuming Garrrett quality is consistent, the only variable is the machining of the covers and balancing. We have had 3 now and they all perform much the same, the engines are different (RB20, RB25 and Neo)so I can't really say that they are EXACTLY the same. I will be putting the one off the RB20 on an RB25 shortly so that might answer that question.

I know, we need a turbo dyno, sorta like a backwards flow bench............

[Roy]

Good question Roy, the cores are a Garret standard part, as are the compressor, turbine, seals and gaskets.  Assuming Garrrett quality is consistent, the only variable is the machining of the covers and balancing.    

Thats the way i see it, the whole machining aspect, what is the level of automation, tolerancing, quality control. Thats my only concern with high-flows, the toolerance between the wheels and housing not being optimal

[SLY33]

I went to GCG today and spoke with Colin (the head guy there?)

He told me that their high flow units offer the same response as the standard turbo. He said something about as they upgrade both comp and exh sides of the turbo proportionally that response is the same. (or something along those lines, cant recall exactly)

But in my mind i didnt think this was possible, to get the turbo making more power, surely something has to be sacrificed in the response??

Then he handed me a ceramic turbine, and it was real light. He then took it back and handed me a steel wheel turbine, and fu(k it was heavy in comparison!! This made me think even more that this thing is definitly gonna take longer to spool up!

Any thoughts on this response issue?

Also GCG are adamant that their units will see 440HP at the engine. Doesnt this mean that the little standard highflow will produce more power than a relatively large HKS 2835ProS rated at only 420PS??

im a bit confused and really need to go for a ride in a GCG highflowed R33!

My HKS2530 equipped car only has 220rwkw, yet running at WSID against a Garret equipped R33 with 260rwkw, we were literally neck and neck the entire strip! Both cars were dynoed in shootout mode on DD dynos, can someone explain how i stayed with him?!

reason im interested is that i want more power and considering a highflow for 250rwkw, but if im even with a 260rwkw car that may have less reponse, i may actually go slower with the GCG 250rwkw turbo?!!?!

With the current 2530 setup ive run a best of 12.5 at 115mph, with a 2.08 60fter. I reckon if i can sort the launch for sub 2sec 60fts that a low 12 is possible. Those of you with GCG's, what times and mph do you run?

[discopotato03]

SK are the compressor wheels on the "Hi-Flow" cores seven bladed , well seven full and seven splitter (lower) blades . If this is the case then the wheels must be TO4S and hardly a high performance item .

Turbonetics and Innovative cores seem to be mainly old school turbos with the annular contact ball bearings using ceramic ball dividers . The results here in Australia have not been good due to bearing failures .

It is wrong to believe that all the performace gains are from the bearing system . With Garretts GT series a lot of effort went into reducing the mass of the rotating assembly particularly the turbine . If you look at the turbines closely they use (mostly) less blades of thinner section and a greater tip height or B width . You could also call this the inducer section , some have described them as open or paddle shaped . Now take a look at its matching turbine housing from the cores side . The channel (nozzel) section that feeds into the turbine blades is generally far wider than T3/T4/std Hitachi (RB 20/25) turbine housings . Now turn it around and look down the turbine inlet (into the mounting flange) and note the cross sectional shape ot the passage . Most GT housings have a pronounced capital "O" shape though parallel vertical sides . Compare this to earlier housings with the narrower chanels and a more "V" shaped volute section . You don't have to be Einstein to see how Garrett has achieved quite high gas flows through compact turbines and housings . Both turbines and compressors are mechanically stronger meaning that they can withstand far higher rpm's without disintergrating . Also Ahh32 the GT2530 does not use the old school T3 compressor wheel . It is a 63 trim 60mm GT wheel . There are three very closely related wheels in this family . The best from an efficiency point of view is that on the GT28RS , 62 trim with slightly greater exducer tip height which gives a few points heigher efficiency in the TO4B cover . The Skyline GTR upgrade GT28 turbo uses a wheel fractionally smaller (inducer) compared to the 2530 . I think they are 47.2 , 47.5 , and 47.7mm . The HKS GT2530 has been around for a while and wheel development is an ongoing thing .

[Sydneykid]

I posted this on another thread, but I think it answers a few of Sly's questions;

We have an R34 GTT that makes 265 rwkw using a GCG ball bearing hi flow of its standard turbo. It has what I call a full bolt on kit (no internal mods though);

Tomei 260 Poncams

Split dump

Hi Flow Cat (very hi flow)

3.25" exhaust

Pod filter

Heat shield

CAI (big one)

R34 GTR standard intercooler

Tomei injectors

Tomei fuel pump

Power FC with boost controller

Low/rear mount exhaust manifold (like an R31 GTSR)

Electric fan

OS Giken twin plate (very light chrome molly flywheel)

Oil cooler

It runs 1.3 bar (all the time, none of this hi/low boost crap)

Fitted over 2 years ago, done 50,000 k's and still going strong. Did an 11.9 at 120 mph on Goodyear Drag Slicks last year. I am not enthused by drag racing, so I only run when I have too. I have tried a couple of turbos on it and this one is my favourite for daily driving, bit of circuit work and the occasional drag session.

Hope that helps