2000 BNR34 new owner

[Joe_Way_Jose]

Hello all...I've consumed many threads from you all for quite some time and figured I may as well going the fray.  I recently purchased a 200 R34 that is pretty much stock aside from a HKS mushroom intake and tomei extreme ti exhaust.  I currently live in Japan and have been talking with mine's and Garage Yoshida to have it overhauled.  Mine's usually goes with the gt2860-1 and -2 turbos from gcg turbo Australia.  My question would be are there better options that are a bit more modern such as gtxs?  I can even source the Nismo R3s for quite a bit less than the cgc kit.  I know there's a hell of a lot more that goes into it than just turbos, but if I am looking for 500-600 whp on a daily driver, what twin turbo setup makes since nowadays?  I know there are exhaustive posts about making this type of HP, but I haven't seen much discussing gtx or Nismo R3s as options.  

[Joe_Way_Jose]

*2000 R34...I shouldn't have used the desktop version of the site on my phone...lol

[PranK]

Welcome!

I'm absolutely *not* the expert in this area so I'll leave others to give more info on your q's.

Its pretty cool to me that Mine's use Australian turbos.

[choyda]

Are you sure you want to stick with twins?

[Joe_Way_Jose]

I think for the sake of hopefully avoiding too much harassment when I import it back to the states and then depending on what state I end up in that staying twins is the way to go.  I'm in the military, so I could end up in some nanny state that gives me grief.

[Predator1]

Congrats..  its compulsary for GTR ownership to stick a big single and a sequential. 

[GTSBoy]

And if you have to drive it in a civilised (or excessively woke) US state, find a way to register and insure it in a redneck state, so you can roll coal in it without worrying about legalities.

[joshuaho96]

On 9/29/2024 at 10:09 PM, Joe_Way_Jose said:

Hello all...I've consumed many threads from you all for quite some time and figured I may as well going the fray.  I recently purchased a 200 R34 that is pretty much stock aside from a HKS mushroom intake and tomei extreme ti exhaust.  I currently live in Japan and have been talking with mine's and Garage Yoshida to have it overhauled.  Mine's usually goes with the gt2860-1 and -2 turbos from gcg turbo Australia.  My question would be are there better options that are a bit more modern such as gtxs?  I can even source the Nismo R3s for quite a bit less than the cgc kit.  I know there's a hell of a lot more that goes into it than just turbos, but if I am looking for 500-600 whp on a daily driver, what twin turbo setup makes since nowadays?  I know there are exhaustive posts about making this type of HP, but I haven't seen much discussing gtx or Nismo R3s as options.  

GTX2860R Gen 2 is an option. No, it doesn't actually do much. The basic problem with wanting 600 whp out of the factory twin turbo setup is a few things. One is that the twin turbo piping is just so, so inefficient. The front and rear turbos are not actually working evenly. The rear turbo is always moving more air than the front. On top of this the OEM rear compressor inlet is rubber that likes to collapse causing a huge intake restriction. The merge doesn't even wait until the intercooler to happen, and it happens at a 90 degree angle. This is why you see some discussion about "turbo shuffle", where in certain conditions one turbo can actually force air to go backwards into the other compressor and stall it out, then once the other turbo recovers it stalls out the first turbo in a cycle until you do something to break out of it. The other issue is that the RB26 is just not that efficient an engine. It needs a surprising amount of ignition timing to reach MBT for a given cylinder pressure so all that time in which the cylinder is pressurizing before TDC is just wasted energy. An N54 might be around 10 degrees BTDC on a stock turbo getting into the boost. An RB26 is closer to 25 BTDC. Net effect is a turbo roughly the size of what HKS uses on the GTIII-SS (smaller than the R3/GCG Japan "GT2860-1" -7s) is only good for maybe 550 crank hp or low 400 whp while a roughly comparable turbo on an N54 can deliver something like 700 crank hp and obviously drivetrain losses are greatly reduced when you aren't burning a bunch of power on keeping a hydraulic pump + transfer case preloaded all the time.

So yes, you can make a lot of power but there's a reason why people go single turbo for the numbers you're asking about. Don't forget that the RB26 can't even do a straight line pull without oil starving on the stock oil pan either. Baffles can help, but really you just need more oil capacity.

Edited October 2 by joshuaho96

[GTSBoy]

12 minutes ago, joshuaho96 said:

where in certain conditions one turbo can actually force air to go backwards into the other compressor and stall it out

Mmmm. Perhaps more correctly stated that the one turbo doesn't actually force air back down the throat of the other. All it does, and all it has to do, is be pumping a little harder than the other turbo (which is an effect of how the turbos are getting driven by the exhaust and inherent resistance to output air flow that each turbo sees up to the merge). If the turbo that is not flowing quite as much then nudges the stall line (because it gets pushed there by the higher flowing one stealing the limelight and moving its own operating point further from the stall line), then you get the behaviour described by Josh. There is no need for air to move backwards in any way. It just needs to be less air moving forwards than is required to stay to the right of the surge line.

[Joe_Way_Jose]

Okay, with all that being said about sloppy blowing from twins, I happily acknowledge the superiority of a single turbo setup on the RB; however, I still plan on double trouble.  I know the -9s were quite popular for some time because they seemed to meet that sweet spot between the -7s and 5s, would introducing VCAM and/or stroking to 2.8L provide the additional displacement/flow to push twins closer to the 500-600 goal?  Does it make more sense for a daily to just do an engine overhaul, slap some -7s on it and enjoy a bit more reliable power?  Has anyone driven a mine's overhauled and tuned engine?  I know they certainly don't approach the power numbers that you drag monsters do down under, but for daily street usage, I just want it to be fun and healthy.

[Predator1]

20 hours ago, Joe_Way_Jose said:

Okay, with all that being said about sloppy blowing from twins, I happily acknowledge the superiority of a single turbo setup on the RB; however, I still plan on double trouble.  I know the -9s were quite popular for some time because they seemed to meet that sweet spot between the -7s and 5s, would introducing VCAM and/or stroking to 2.8L provide the additional displacement/flow to push twins closer to the 500-600 goal?  Does it make more sense for a daily to just do an engine overhaul, slap some -7s on it and enjoy a bit more reliable power?  Has anyone driven a mine's overhauled and tuned engine?  I know they certainly don't approach the power numbers that you drag monsters do down under, but for daily street usage, I just want it to be fun and healthy.

Just realised your profile. Are you in Japan? I'm in Tokyo currently. hit me up if you're in Japan man.

[joshuaho96]

21 hours ago, Joe_Way_Jose said:

Okay, with all that being said about sloppy blowing from twins, I happily acknowledge the superiority of a single turbo setup on the RB; however, I still plan on double trouble.  I know the -9s were quite popular for some time because they seemed to meet that sweet spot between the -7s and 5s, would introducing VCAM and/or stroking to 2.8L provide the additional displacement/flow to push twins closer to the 500-600 goal?  Does it make more sense for a daily to just do an engine overhaul, slap some -7s on it and enjoy a bit more reliable power?  Has anyone driven a mine's overhauled and tuned engine?  I know they certainly don't approach the power numbers that you drag monsters do down under, but for daily street usage, I just want it to be fun and healthy.

VCAM doesn't really increase peak power, it just widens the powerband. So if you were giving up power with adjustable cam gears to get better low-end response yes in theory it "increases power" but otherwise not really. Stroker kit might put you in a more efficient region of the compressor map which will get you more power but at say 7000 rpm I'm not sure that much will change.

The original HKS GT2530, -5s, and GTX2860R gen 2 are all roughly the same kind of turbo. If you want 600 horsepower those are the turbos you need. So 500 whp. Just expect to spend some quality time trying to figure out intake/exhaust piping. The "twin turbo" pipe is an obvious place to start. Make sure the actuator preload and all of that fun boring stuff is set up correctly. Throw a VCAM step 2 at it if you want good response, 2.8L stroker too.

If you're not actually wedded to 500 whp all the time you can barely get there with -7s or Nismo R3 turbos, you just have to run E85 or race gas and run them hard: