Gcg Turbo Shot.

[skylinecouple]

Well,after 100,000km my gcg turbo has enough shaft play to warrant replacement.After reading every post totaling 10 casillion I am close to deciding which way to go.The rebuild for the hi-flow is out of the question as it won`t flow enough air without cams as is the slide hi-flow for the same reason.For my R33 GTST with R34 motor I am chasing 240rwkw but at no more than 16lbs of boost.I also want to be able to bolt it on in the garage without having to chase custom parts over a week.I know GCG also do a mounting kit for the GT 30`s ie:3071,3076 but maybe the 2535 or GTRS?The idea is to have 240 or even 250 but not beating the air so badly the intercooler works overtime in three laps of wakefield.And no,my car is not a money pit so $3000 or under please and no cams as previously stated.There are some very clever people here so I hope you can help since my holidays start soon and I need to have it all ready to go by then.

I have all the goodies.PFC,injectors full 3" and split dump.Nismo pump.Front mount.

[skylinecouple]

Just leaving for dinner date but will be back in an hour.

[CEF11E]

I think you will get VERY close to your power goal with the hiflow. I am making 240rwkw on an RB20 with a slide hi flow at 18psi.

I am sure there are guys making this on RB25's with 16psi?

just checked RB25 turbo upgrade thread. there is 1 person making 265rwkw at 17psi and another person making 235rwkw on 13psi

[benl1981]

thats bad about the high flow.. It musn't be that much more than 4 years old, since they haven't been making them that long. I would expect it to last a lot longer than that..irrespective of km..

[BAMR33]

$3k!... go HKS if your installing yourself

[skylinecouple]

Yes I must admit I don`t know why the shaft would have so much play but I have a standard turbo with 32,000km on it sitting on the bench and there is zero play in any direction.If I pour a little vegie oil in it and spin it,goes on for a few revolutions.Same thing with the old hi-flow and maybe one rev.I`m very worried if I get a slide stage 3 or rebuild the GCG I`ll not come close to 240.Imagine going to all that trouble and you end up back where you started from.

[paulr33]

you should be able to get 240rwkw with 16psi on a highflow.

it should be even easier on the neo 25t.

you wont need cams for 240rwkw, i wouldnt expect so.

normal ball bearing turbochargers (well nissan ones) i think have rebuilds at 100,000 kms so it sounds fairly normal. its usually that most survive past this. i would be interesting to check say an s15 service schedule from an aus nissan dealer.

[skylinecouple]

Nic,I think there was one guy making 265 but I really think that would be with cams.What about the 2535 is that direct bolt on? Brett,is that the GTRS your talking about? That is one option I`m really considering but there are so many differing power figures from similar setups from that turbo.

[skylinecouple]

Thats the trouble Paul,I know I SHOULD be able to make that power but what if I don`t? The hi-flow I have now only made 220 after I got the injectors and only made 1.5 to 2kws for every pound of boost after 14lbs.I had 18lbs in it to get the 220.That isn`t very efficient.Bear in mind perhaps my hi-flow bing so old may be an early attempt by GCG or they used a RB20 rear housing.

[paulr33]

sounds like a restriction somewhere

do a dyno run with the dump pipe dropped off

see how much power it makes

what are all the mods?

got a dyno sheet ?

[skylinecouple]

Will try to post up dyno sheet but I`m totally useless as I work constantly.Though there was a huge dip at around 5 to 5,500.Just put in biggest metal cat I could find.I have been thinking Paul,that maybe I will do that as I made the dump myself and only used 1" pipe for 10" then blended in to 2" pipe. I think I`ll make another one with 2.5 and 1.5".

[Bass Junky]

for $3k you could get the cams and a new highflow, which will be cheaper because you don't need the machining..... Just new wheels and bearing.

[Dale FZ1]

Thats the trouble Paul,I know I SHOULD be able to make that power but what if I don`t? The hi-flow I have now only made 220 after I got the injectors and only made 1.5 to 2kws for every pound of boost after 14lbs.I had 18lbs in it to get the 220.That isn`t very efficient.Bear in mind perhaps my hi-flow bing so old may be an early attempt by GCG or they used a RB20 rear housing.

Well my high flow has the smallest trim 48T 2871 core fitted. Still made 295hp (219kW) @ 14psi which dropped to 12psi by max power rpm. There is marginal scope for improvement, but plots show that it will quickly head into choke as you've described if I try to push it beyond 15psi. I have a 14psi actuator going on, and will be happy with whatever it yields.

So yours should be capable of at least similar - do you know if your ignition timing was really conservative - it was amazing to see the power numbers rise as the ignition was progressively advanced over consecutive runs

RB20 and R33-spec RB25 turbine housings and impellers are the same size.

If going for something high flowed for the Neo motor, you would be mad to use anything other than the OP6 turbine housing. Bigger flow + deeper breathing through the improved variable cam timing setup will give the potential for both a better mid range and higher top end.

Do a search on high flows for jmac - he got some pretty tidy results on a R34 last year. Try around 250kW @ 16psi or so.

Alternatively with 3G to spend, I'd consider a Slide unit + cams and still come in well under.

Edited March 5, 2007 by Dale FZ1

[skylinecouple]

I was quite impressed with your result Dale and congratulations.But I really need to go quite a bit bigger to get the 240 I`m looking for.To be honest,I have thought about cams if for nothing else than the angry idle. However,I really would like that bigger number without the cams as I hate opening up a perfectly good engine.

By the way,the turbo I have that came with the new engine is in fact a series 11 as the engine was from the very last of the series11.They started using them towards the end of the run with the series11 turbo,DAMN.

[skylinecouple]

Forgot to mention the timing is limited to 15 deg. at the top end.Tuner can`t put any more into it which leeds me to believe the turbo is way to small and causing a restriction.

[MANWHORE]

That's pretty bloody ridiculous if you ask me. Either there's someting wrong with that particular turbo (faulty bearing cartridge) or something wrong with all of the bearing cartriges that they use.

Skylines running the stock turbos have done well over 150-200 000 ks still running the same turbo.

Edit: I just htought of something else. Perhaps there might be a reason why your turbo has worn out so quickly. Do you have an oil supply problem? What oil do you use? brand and viscosity. How often do you change it?

How much boost have you been running? how do you drive it? track? etc.

I'm just suggesting that perhaps, you have a look to make sure that the motor itself and oil supply is actually ok, so that the new turbo deosnt' do the same thing.

Edited March 5, 2007 by MANWHORE

[MANWHORE]

PS: the gcg turbos are great turbos. sydneykid has reached 265 rwkw on an rb25 (with cams).

Without cams, It should do 240 easily. Whether it does it at 16 psi I don't know. Is there any reason why you're worried about putting an extra 1-2 psi into it?

A vg30/gtt turbo gcg highflow will do it even easier with less boost.

[Dale FZ1]

I was quite impressed with your result Dale and congratulations.But I really need to go quite a bit bigger to get the 240 I`m looking for.

Agreed.

If you've got R33 spec housings, I would suggest using the 56T 2871 core. It will provide the airflow required to make 240 (not too hard) - 250 (a bit harder), without the risk of surge.

My full load ignition timing is at 24 degrees up to 4000, then drops-rises-drops -2, +2, -1 in the remaining range up to 6800. If your base settings are right, then you are missing out on a lot of power if you have 15 deg at full load.

With your budget I'd be aiming for the cams specifically to make the power without having to use high boost levels. And yeah, the more urgent exhaust note is an added bonus.

[skylinecouple]

Manwhore,oil is changed every 3000km.It is a mystery why it has so much slop.If I can locate a vg30 housing I might give GCG another go.Dale,that 56T 2871 could be good as long as I don`t have to find a heap of parts all over Sydney to do it.If I move away from the hitashi core I might as well go to the 30 series though.

[Slide]

Nic,I think there was one guy making 265 but I really think that would be with cams.What about the 2535 is that direct bolt on? Brett,is that the GTRS your talking about? That is one option I`m really considering but there are so many differing power figures from similar setups from that turbo.

mickR33 is making 265 without cams at 17 psi OP6 rear housing so it still has a bit in it.

Dyno Sheet

Modifications for his car are: Power Fc, FMIC, full exhaust, Nismo reg, Bosch 040, Z32 AFM and using

a turbotech boost controller.

Best results:

279rwkw on vg30 max oversize 19psi

268rwkw rb25 housings with stage 3 max oversize turbine 19 psi

262rwkw rb25 housings with stage 2 turbine 19 psi

249rwkw rb25 housings with stage 1 turbine 18 psi (much smaller major diameter - used when asked to mainly on RB20)

Nic holds the best power rating for RB20 241rwkw stage 2 turbine at 19psi

Results would have varied slightly from DYno to Dyno.

Our Dyno will hopefully be installed at the end of this month then the real in car R&D will begin on the same car for best results.

18psi is the best for psi vs gain