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Hks Gt-rs - Rb25det

justin911

By justin911,
in Engines & Forced Induction

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R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Fark paying trade paul, no need...

When did you get that quote? I have just been informed that Garrett have raised their prices. Can you please confirm the price.

:mad:

Garrett GT28 series have been that way for donkeys. There has been no price rise at all.

$1674

http://www.horsepowerinabox.com/HPIAB2/prod414.htm

The GT30 add around i think $100 an so on. They are all very similar.

Considering i paid $3300 landed for twin HKS turbos.. 2.7k for just one is pretty painful

Abo Bob Grand Master

Abo Bob

Posted
Posted
Hey Abo Bob,

Thanks for your e-mail, i appreciate your input.

Just one question:

Between 2k-5krpm how much timing are you running?

You also mentioned an issue with porting, but the example you used related to an rb26. I personally would not touch the head of a 26, as they were engineered for race purposes, apart from port/manifold matching as stated. The rb25 on the other hand is totally different and i still believe gains are had from porting, provided it is done by a profesional porter.

I run stock R33 S1, rb25det, compession. (i think it is 8.5:1 or 9:1??????)

Hey mate. Ignore that last pm obviously.

I was going to say that I don't know what timing but I went out to the car and took it for a run and logged the data for you.

Porting is still an issue. Bigger ports will always give the escaping gas a lower velocity and your turbo needs high velocity, high energy gases to spin it quickly.

Stock compression ratio is 9:1. Are you sure this didn't change when you had the head work done?

Run_1.zip

Interloper Veteran

Interloper

Posted
Posted
I think this turbo in any version is a POS and you can do better . Sure the compressor may push enough air for ~ 400 Hp but the 53.85mm turbine in a .64 GT28 housing - very sceptical . HKS claim 300 wheel PS out of their own demo Silvia - they would claim more if they could ....

Cheers A .

They claim 294kw out of the GTRS with 256 cams on their website for the SR20. But is it rwkw? probably not....

sr20_graph.jpg

Al Grand Master

Al

Posted
Posted
Hey mate. Ignore that last pm obviously.

I was going to say that I don't know what timing but I went out to the car and took it for a run and logged the data for you.

Porting is still an issue. Bigger ports will always give the escaping gas a lower velocity and your turbo needs high velocity, high energy gases to spin it quickly.

Stock compression ratio is 9:1. Are you sure this didn't change when you had the head work done?

THANKS!!

Really appreciate all your help. I asked my mechanic today what timing my car is running at mid to low rpm and he stated 24-26deg, so this may be my problem with lag. Where the recorded runs done at full throttle?

I understand your view on porting but i do not regret my decision, as a experienced porter will know how much to remove and where it is required. When discussing porting with the technician, he always stated that the best porting is done when you know what NOT to remove and what to leave alone.

The guy i used has been in the trade for years........ and ports heads for the V8 supercars, as well as other forms of motorsports.

Abo Bob Grand Master

Abo Bob

Posted
Posted
THANKS!!

Really appreciate all your help. I asked my mechanic today what timing my car is running at mid to low rpm and he stated 24-26deg, so this may be my problem with lag. Where the recorded runs done at full throttle?

I understand your view on porting but i do not regret my decision, as a experienced porter will know how much to remove and where it is required. When discussing porting with the technician, he always stated that the best porting is done when you know what NOT to remove and what to leave alone.

The guy i used has been in the trade for years........ and ports heads for the V8 supercars, as well as other forms of motorsports.

V8 don't have turbos that need high velocity gas to turn them though. Anyway, enough about that. WE understand each other.

Those runs were done at full throttle. I think there is a tps value in the spreadsheet somewhere??

Sydneykid Grand Master

Sydneykid

Posted
Posted
Porting is still an issue. Bigger ports will always give the escaping gas a lower velocity and your turbo needs high velocity, high energy gases to spin it quickly.

Not if the ports are restricting the flow. By opening them up you get more flow.

You also mentioned an issue with porting, but the example you used related to an rb26. I personally would not touch the head of a 26, as they were engineered for race purposes, apart from port/manifold matching as stated. The rb25 on the other hand is totally different and i still believe gains are had from porting, provided it is done by a profesional porter.

If I put an RB26 and an RB25 cylinder head side by side you would be hard pressed to pick the difference (without looking at the stud patterns). RB cylinder heads are not as good as some people claim, grossly obverrated. The basic design is good, but they are still a mass produced, cast alloy production car part, designed in 1988 and made to a price.

:) cheers :O

Al Grand Master

Al

Posted
Posted

I realise V8's require different flow capabilities, just was pointing out the level of skill/experience/reputation my porter has. He also explained the differances between porting n/a heads and turbo heads.

Thanks again for the data, will really come in handy.

Sydneykid, thanks for you last post, as i feel more justified that i decided to port the head.

  • 2 months later...
R33-Lovr Enthusiast

R33-Lovr

Posted
Posted (edited)

might help..

i've got da HKS GT2835R on my rb25 that did 248.3KW at 15psi.

engin mods

front mount

3.5" exhaust

hks f-con v

hks Electronic valve controller, i played with this when i got it and i think i might of fked up the fuel ratio and sht cause on the dyno, the fuel and air ratio was all over the place, i'll have to take it to BD4s who can program the F-con V, and by that i know i can get more out of it.

stock coils

i mean 250kw is more then enough

i hope this helps in a way

Edited by R33-Lovr

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