R34 Gtr - Between 300rwkw & 350rwkw

[adamp2403]

Hi folks.

Am new to this site, although have owned 2 great Skylines over the past 8 years or so;

I now have an R34 GTR '99 non V-spec;

• Recently fully rebuilt engine (UAS Sydney), as previous owner(s) was not a believer in oil changes.
  
• Nitto 20thou o/s pistons & rings.
  
• Apexi Power FC D-Jetro.
  
• Nismo oil cooler kit.
  
• Full 3.5" stainless system from turbo's back.
  
• OEM turbo's fitted with metallic turbines.
  
• Nismo 600cc injectors.
  
• OEM intercooler.
  
• Boost peaks at 19psi and then drops off to approx. 15-16psi at the very top end.
  
• 520Nm @ rear wheels (4400rpm).
  
• 316rwkW.
  

Low range torque & punch not as good as my earlier single turbo RB25DET R33.

Considering a modest turbo upgrade to see if we can achieve perhaps around 350rwkW and additional midrange torque, but don't wish to suffer much further lag. Not interested in only chasing kW's at the top end, but still have a meaty torque curve.

The Garrett "-5" twins have been recommended, although some say the added lag and potentially less midrange may disappoint me after spending the thousands $$. Had a nice HKS GTRS turbo on the R33, and it was lovely. Don't really want to fork our extra for twin HKS units above the Garretts unless it is truly justified.

Have reviewed quite a few posts on this site on the RB26DETT turbo upgrades, although personal requirements differ, and even similarly spec'd cars seem to get measurable differences/results.

Any constructive advice would be greatly appreciated.

Thanks fella's.

Cheers

Adam

[Deano 1]

your gunna find it very hard to not get any lag diffrence when goin to a bigger turbo than factory mate. id just go the -5 and have someone tune it well, get your self a pair on cam gears, you can get em to come on alil earlyer with the stardard cams.

[R31Nismoid]

Same as the bloke who asked a similar question not 2 days ago:

http://www.skylinesaustralia.com/forums/Tu...ss-t346302.html

You NEED to read the thread that FULLY goes into detail about these turbos. This has been covered so many times that it's getting quite tedious.

No TT combo is going to be as responsive as a single GT-RS on a RB25. You are talking 250-260rwkw of turbo vs 300-340rwkw, its simple impossible.

If you want outright response on a 2.6ltr "-5s" are a stupid recommendation.

You want -9s (GT-SS). They are the most responsive you can get other than stock turbo's. They start building boost hard from 3300rpm give/take.

[fatz]

you have 4wd, traction smooths out the power delivery and you don't feel as fast but in reality you are going faster

[Touge Kyousou]

Pretty easy to get traction with GTRS turbo though..

[DVS JEZ]

and also the added weight.

do you have a dyno sheet with your current setup?

you could try adjustable cam gears to bring the power on earlier although if your max torque is at 4400RPM 520NM thats already pretty early, my RB26 has max torque around 5500

[R.3.2.G.T.R]

Gt-ss + e85 = 350kw

[adamp2403]

Same as the bloke who asked a similar question not 2 days ago:

http://www.skylinesaustralia.com/forums/Tu...ss-t346302.html

You NEED to read the thread that FULLY goes into detail about these turbos. This has been covered so many times that it's getting quite tedious.

No TT combo is going to be as responsive as a single GT-RS on a RB25. You are talking 250-260rwkw of turbo vs 300-340rwkw, its simple impossible.

If you want outright response on a 2.6ltr "-5s" are a stupid recommendation.

You want -9s (GT-SS). They are the most responsive you can get other than stock turbo's. They start building boost hard from 3300rpm give/take.

Digger.

Like I said, I am new to this site, and yes I did spend quite some time on Google searching for info. I'll have a look at the above thread - thanks.

Yes, I already have adjustable cam gears - forgot to mention that initially.

Cheers

Adam

[Harey]

If you liked the HKS GTRS on the RB25 then you are a response man, its good to work this out before you start purchasing. People can have very different opinions on the same turbo.

Get some -7 or -9 turbos and you will have very close to the same response you do now, but with more mid and top end. Then add E85 as said above to make even more power!

[bradsm87]

Garrett -9 turbos will do the trick. They are the same as HKS GT-SS but cheaper. Great turbos. RB25's have 9:1 compression and VTC as well as being a lighter car which is prob why it was faster.