Opinions please - Time for a turbo for my GTSt

[Blade]

Love it how people can say if i change my turbo from this to that ill get 250rwkw and 300rwkw, of course the larger the turbo the greater the boost the larger the gain, but u cant assign a figure to the turbo you get...your engine could be rooted maybe reach 300rwkw or 250 rwkw and u hammer it a couple of times...boom blown piston

it depends on ur engine condition, and dyno conditions

Anyone can tweak a dyno reading, best way to see what power your car is pulling is take it to a track, dyno is really only good for tuning imho.

[Sydneykid]

Love it how people can say if i change my turbo from this to that ill get 250rwkw and 300rwkw, of course the larger the turbo the greater the boost the larger the gain, but u cant assign a figure to the turbo you get...your engine could be rooted maybe reach 300rwkw or 250 rwkw and u hammer it a couple of times...boom blown piston

it depends on ur engine condition, and dyno conditions

Anyone can tweak a dyno reading, best way to see what power your car is pulling is take it to a track, dyno is really only good for tuning imho.

Ahhhhh no! :dump:

"the larger the turbo the greater the boost the larger the gain" that's not correct, if I choose the right turbo I can actually have more power at lower boost levels. Boost is a measure of restriction, airflow is what makes power. :idea:

If I do a leak down test, check out the internals with a bore scope, drain the oil and have it annalised, I can tell what condition your engine is in, pretty much spot on. If I use a Dyno Dynamics dyno running in Shoot Out Mode, it is very difficult for me to a get false result, one that is impossible to pick anyway. :angel:

This is much more reliable than taking it to "the track" where driver skill, suspension set up, tyres, ambient conditions etc etc make much more of a difference than a tricked dyno. :headspin:

And if you get "boom blown piston" then put that down to poor tuning and diagnostics, it's got absolutely nothing to do with "hammer". Exceeding the limit of the metalurgy will also do it just as effectively. :innocent:

There is much to learn, that's why I come here. :aroused:

[Blade]

Nah mate...i was just sayin how people rekon by buying a big arse turbo theyll get 300+rwkw...they flash their dyno readings around with big figures, which can be bs yeah? i heard from someone that dynos can be tweaked to show false readings

I also heard that ur power output in the end really is determined by ur engine cond, fine having a dyno sheet with a big number but wat does it prove...Damnit...ah well ...better stop typing or ill get myself into a bigger hole

[Blade]

I know a blown piston is due to overtuning/badtuning

But i heard from my mechanic, customers who hear about these turbos outtputting large hp, they undertune for a reason, customer is not happy wonders why he aint gettin more, takes it to another tuner to get more power, thinks hes great with a big reading, 2 days later car is on a truck with a blown piston

/waits for sydneykids smackdown :Oops:

[dojobi]

Honestly MIC33R, I have no idea what the specs are, it is an off the shelf GCG RB25DET ball bearing hi flow.  If I had to guess it feels like no bigger than a 0.64 A/R Turbine Housing with around a 76 trim turbine in it.  The Compressor Housing looked to around 0.70 A/R with maybe a 48 trim compressor.  But all that is really guess work, I have deliberately never measured one.

Thanks SydneyKid. A guess at its size is better than nothing to me That size sounds like it'd be nice and responsive on a 2.5L Neo.

Cheers,

Michael

[Blk33]

We have an R34 GTT that makes 265 rwkw with the following;

GTR fuel pump (SAU forum)

3.5" exhaust ((from Performance Metalcraft)

HKS POD with heat shielding and large CAI (SAU forum and self made)

R33 GTR standard intercooler (SAU forum)

RB25DET turbo with ball bearing hi flow (by GCG)

Split dump and engine pipe combo (from Performance Metalcraft)

Hi flow cat (SAU forum)

Power FC with boost control kit (Nengun)

Tomei Poncams 256 @ 9.2 mm (Nengun)

Nismo fuel pressure regulator (Nengun)

Tomei Injectors (Nengun)

Hi SydneyKid

I have read a little about the GCG hi flow RB25DET. Look like good value for money.

What sort of loss in mid power over a standard turbo would you expect and does that outweigh the increase in top end?

I love the mid range power available with 12psi on the standard turbo.

I am worried it will be a dog with the high flow.

[Roy]

It has more power EVERYWHERE than standard, so it has awesome average power.  It gets driven everyday

With cams it looks as though it doesnt lose anything in the midrange

Get a copy of HPI #22, it has a dyno printout of an R34 with PFC, exhaust, intercooler, filter, with std turbo, then GCG hi-flow overlayed on the same print out

[Sydneykid]

I know a blown piston is due to overtuning/badtuning

But i heard from my mechanic, customers who hear about these turbos outtputting large hp, they undertune for a reason, customer is not happy wonders why he aint gettin more, takes it to another tuner to get more power, thinks hes great with a big reading, 2 days later car is on a truck with a blown piston

/waits for sydneykids smackdown  :Oops:

Your wish is my command :slap:

Your example is somewhat valid exept there are 2 problems;

Mechanic #1 should have told the owner why he undertuned (your word), I prefer "left a margin for safety".

Mechanic #2 deserves the suing (and bad rep) that he is going to get. :wassup:

If you hang around here and read enough you will find a lot of information that, as a car owner, will help stop this happening to you. A dyno read out with A/F ratios, ignition timing, boost and a few others will help you (and other willing helpers) diagnose exactly what is going on. You will know what mechanic #1 has done and it will also help you stop mechanic #2 from doing something stupid.

As I said, much to learn around here, worth the time though as it is priceless.

[Sydneykid]

What sort of loss in mid power over a standard turbo would you expect and does that outweigh the increase in top end?

As Roy posted

With cams it looks as though it doesnt lose anything in the midrange

and he is absolutely correct. We found that we get more power EVERYWHERE, on boost, off boost, even at idle it has more power. But we never just stick a turbo on, there are lots of other things that make a dfifference, refer previous list.

[specialk]

which GCG turbo is it, the stage 1 or 2.,..

and what boost level?

cheers

[Guest Robo's]

With cams it looks as though it doesnt lose anything in the midrange

Get a copy of HPI #22, it has a dyno printout of an R34 with PFC, exhaust, intercooler, filter, with std turbo, then GCG hi-flow overlayed on the same print out

What was the dyno print difference?

[Sydneykid]

which GCG turbo is it, the stage 1 or 2.,..

and what boost level?

cheers

Hi specialk, we only ever use the 450 bhp spec (Stage 1), personally I believe the 500 bhp spec (Stage 11) runs too close to the surge limit on an RB20/25 for my liking.

Re boost, you need to remember that boost is simply a measure of restriction to airflow. It is airlfow itself that makes power, boost is pretty much irrelevant. If you remove the restrictions in your engine, then you can make more power at lower boost levels. Noting thta we never simply bolt a turbo on, we always do other things, stuff like this on our R34GTT;

GTR fuel pump (SAU forum)

3.5" exhaust ((from Performance Metalcraft)

HKS POD with heat shielding and large CAI (SAU forum and self made)

R33 GTR standard intercooler (SAU forum)

RB25DET turbo with ball bearing hi flow (by GCG)

Split dump and engine pipe combo (from Performance Metalcraft)

Hi flow cat (SAU forum)

Power FC with boost control kit (Nengun)

Tomei Poncams 256 @ 9.2 mm (Nengun)

Nismo fuel pressure regulator (Nengun)

Tomei Injectors (Nengun)

None of the above is any use unless you can get the power down, so;

OS Giken twin plate clutch (SAU forum)

Plus it has to be reliable;

Oil cooler and remote filter (Earls)

It has more power EVERYWHERE than standard, so it has awesome average power. It gets driven everyday, does some circuit work and the odd drag strip (11.9@120 mph) and has been for almost 2 years.

So, at ~1.4 bar, it doesn't run a lot of boost compared to what I see others running for less power.

Hope that answered your questions.

[OREX]

Let me jump in here guys.

My RB20DET runs a HKS stainless manifold, HKS 2530 with HKS wastegate actuator and small internal 'gate, big fuel pump, big injectors, Apexi front mount, HKS cams and gears, big exhaust, old school AVCR and RSM as well as an Apexi fuel computer. with an exhaust leak i made 291.5kw and 1039Nm. i won't say where but does this sound good to you. boost hits hard on 12psi at roughly 4500rpm. makes for interesting driving. good luck.

[Marlin]

Well after having driven quite a few upgraded 33's, I'd go with a HKS 3037S kit, it just has a fantastic balance of power versus response. Seems to make the power without montrous boost too.

[BOOSTD]

Let me jump in here guys.  

My RB20DET runs a HKS stainless manifold, HKS 2530 with HKS wastegate actuator and small internal 'gate, big fuel pump, big injectors, Apexi front mount, HKS cams and gears, big exhaust, old school AVCR and RSM as well as an Apexi fuel computer. with an exhaust leak i made 291.5kw and 1039Nm. i won't say where but does this sound good to you. boost hits hard on 12psi at roughly 4500rpm. makes for interesting driving. good luck.

What the... 291.5kw @ 12psi hmmnn

[Marlin]

What the... 291.5kw @ 12psi hmmnn

Yeah..........

[Sydneykid]

Let me jump in here guys.  

My RB20DET runs a HKS stainless manifold, HKS 2530 with HKS wastegate actuator and small internal 'gate, big fuel pump, big injectors, Apexi front mount, HKS cams and gears, big exhaust, old school AVCR and RSM as well as an Apexi fuel computer. with an exhaust leak i made 291.5kw and 1039Nm. i won't say where but does this sound good to you. boost hits hard on 12psi at roughly 4500rpm. makes for interesting driving. good luck.

Wow that's fantastic! That's the most powerful standard internals RB20DET I have ever heard of. Care to put up the dyno sheet?

[OREX]

Yes i do understand what you guys mean. i didn't keep the dyno sheet, but i also didn't pay for the session. just wanted some feedback dudes. i'm thinking like 200-250 HP topps, don't know what the dyno guy was on!

[OREX]

oh and i forgot to say this car was bought this way, with many unknown mods.

[Sydneykid]

Time for a reality check, the Gibson RB20DET made 460 bhp for qualifying at 2+ bar, but they turned it down so it would last for the race to 420 bhp (that's ~260 rwkw). Admittedly that's with a circuit race power band, not a dyno queen one. I suspect 291.5 rwhp (215 rwkw) might be closer to the mark. :idea:

But I could wrong.