What turbo to pick for an RB25DET-NEO in a 34 GT-T

[adznight]

****I know it’s been discussed a lot already so don’t flame me ****

Ok I'd like to upgrade the standard turbo on my 34 and am hoping to have between 250kw-300kw at the wheels. I've got a Power FC, AVC-r and am looking to also upgrade fuel system (If I need to?) and exhaust system to a turbo back. At this stage I've been looking at the HKS 2530 and the HKS 2540. I know there has been a LOT of discussion about these turbo’s on RB25's but not much on RB25 NEO's from what the search brought up. I’d love to hear form people that know a bit about after market turbo's on 34's so I can make a better decision and just get a better general knowledge of them – Cheers!

[franks]

planning on doing the same with the same car! power output for me is targetted slightly lower though - 250rwkw? but im looking for lots of bottom and mid range.

for 250-300rwkw, neither the 2530 or 2540 will get you there. you are looking at atleast a low mounted HKS GTRS (i reckon good for about 250-270rwkw) or a top mounted 3037 or 3040. both should get you there..

are you okay with a top mount? you will need a custom manifold made up for it.

as for fuel mods, definately! there's a general formula used to calculate the required injector size for the power levels you want i think 480 or 550cc injectors will be good enough for me, if you're looking at more, you'll need 750cc i reckon. you'll also need a bigger fuel pump and possibly rising rate fuel regulator.

you will most definately need to budget a clutch and larger air flow meter and possibly throttle body.

[benm]

Yup you'll deffinetly need a larger flowing fuel pump. As a guide the Bosch 040 cost me $340 fitted.

*Std GTST pump is 135 litres per hour and supports 300 bhp at standard pressure

*Std GTR pump is 190 litres per hour and supports 420 bhp at standard pressure

*Bosch 910 pump is 200 litres per hour and supports 450 bhp at 73.5 PSI # 0 580 254 910

*Bosch 975 pump is 228 litres per hour and supports 500 bhp at 73.5 PSI # 0 580 254 975

*Bosch 984 pump is 228 litres per hour and supports 500 bhp at 73.5 PSI # 0 580 254 984

*Bosch 044 pump is 330 litres per hour and supports 730 bhp at 73.5 PSI # 0 580 254 044

*Bosch 040 pump is 235 litres per hour and supports 520 bhp at 73.5 PSI # 0 580 254 040

[adznight]

Hey guys, thanks thats a great start. Chances are I'll be looking at a custom manifold anyway for better flow and less heat. Yeah I forgot to mention the clutch and injectors You think I may need an AFM too hey? Apart from the mounting location of the turbo, what differences are there between hightop mount and standard mount apart from oil lines etc?

[adznight]

I was reading a lot of old theads last night and one good point was raised by Sydneykid that people go out and spend a lot of money on a new turbo but dont budget for the follow up like fuel system, clutch etc and end up with thier car running like dog. One person also said that it's possible to eliminate the AFM and replace it with a MAP sensor, wonder if the Power FC can do that?

[Steve]

Buy some back issues of HPI, all your questions will be answered.

For turbo, HKS 2835 (new can be had for 3.5k, second hand around 2-2.5 in good condition) very good repsonse and builds boost quickly or something like a TD06 - bush bearing, wont spool up as quickly but will be cheaper and can be rebuilt.

Or, you could read boostds thread about his home made high flow. Basically a stock turbo with a larger compressor wheel and a vg30 turbine housing that has been opened up.

Once again though, a bit more lag than a something like the 2835.

[adznight]

Yeah I prefer to go for a HKS purely for thier response and reliability. I've got a couple of the older issues, how far we talking? Maybe 230-250 rwkw is a more realistic figure for the momment

[rob77]

I'm making about 250kw @ wheels on a td06-20g with a 16cm exhaust housing. With a good exhaust manifold and ecu it should spool up by 4000rpm (currently spooled by 4300rpm on the stock exhaust manifold) and people say that with an adjustable exhaust cam gear it should spool up by 3500rpm. Power delivery is silky smooth, do a search for "trust td06 stage" and you'll find a copy of my before and after dyno curves (before ecu and after), the difference a good fully tunable computer makes is huge. However to get closer to 300kw @ wheels, I'm gonna need a new exhaust manifold (will be done eventually now cos the stock one is going to break one day) and some good pistons so I can crank the boost up to 17-18psi, even then I think I'll max out around 280-290kw dont think I'll quite hit 300kw.

[adznight]

Are there many differences between Trust and HKS turbo's? I'd imagine there would be. You have it mounted on the stock manifold hey? I didn't think the td06-20g could go on a stock manifold.

[Sydneykid]

Hi Adzmax, as the guys have said, there is huge difference in cost between 250 rwkw and 300 rwkw. Almost all the support stuff on an RB25 reaches it's limit around 250 rwkw. It will easily cost double to go over 250 rwkw, you will need stuff like injectors, exhaust manifold, camshafts, fuel pressure regulator, BOV, wastegate, fuel pump, dump pipe, hi flow cat, 3.5" exhaust, radiator etc

My suggestions would be For around 240 to 250 rwkw, ball bearing hi flow your standard turbo. Plus a split dump, 3" exhaust, Tomei 256 Poncams, POD with heat shield and CAI, Power FC ECU with boost control kit, standard GTR fuel pump and a standard GTR intercooler. That's about $10K worth.

For 300 rwkw simply double the cost. If you want to spend $20K then I can give you the list for that in another post.

Hope that helps

[adznight]

Hey thats what I wanted to hear, thanks thats great! Yeah I see your point with the high power figures, I think 250rwkw might be the go. I already have the Power FC, GTR Front mount and AVC-r so I'm well on the way.

You wouldn't belive it but I was soooo close to picking up some Tomie Poncmas at a great price the other day, I'm gonna be kicking myself all weekend now. Not the 260's huh? I was thinking a fuel regulator too?

With the high flow standard turbo that involves changing a housing and the rotor yeah? So it would be a hybrid. Is it purely a cost thing not going for an aftermarket bolt on or you just dont see enough of a performance gain?

[adznight]

This may sound dumb but whats the CAI? What about a panel in the standard air box?

[benm]

Cold Air Intake (ie an air feed ducting straight into the pod box.

I'd just throw in a K&N Panel Filter leaving the standard airbox intack.

[Sydneykid]

Hi Adzmax, CAI = Cold air intake, but a panel filter in the standard box is OK. You're right, I think the Tomei cams are 260 for the R34, we use alot of 256's in R33's and R32's so I get them mixed up.

Regardless of whether you are going to use a POD or a panel, make sure the inlet hose from the AFM to the turbo is in good condition (not soft). We have seen a couple of R34's suck them closed at high airflows. A problem that is very hard to trace, as soon as you stop to check where the power went, it expands to its normal shape and you can't see anything wrong.

I can't speak for all hi flows, but we use GCG and they do ball bearing (most cheaper hi flows are plain bearing) upgrades. Turbo gets a full recondition, new seals, shaft, micro balance etc. The fit larger stainless/inconnel steel compressor and turbine wheels and machine the standard housings to suite. It's great way to do it as everything bolts straight back up and looks standard.

Hope that helps some more

[adznight]

Ah damn it it WAS those cams. Sh*t. lol.

[adznight]

Apart from cost is there much of a difference between a hybrid rebuilt R34 Turbo and a HKS turbo? I mean spool times, flow and performance?

Thanks very much for your imput guys! Much Appreciated

[rob77]

Originally posted by Sydneykid

Hi Adzmax, as the guys have said, there is huge difference in cost between 250 rwkw and 300 rwkw.  Almost all the support stuff on an RB25 reaches it's limit around 250 rwkw.  It will easily cost double to go over 250 rwkw, you will need stuff like injectors, exhaust manifold, camshafts, fuel pressure regulator, BOV, wastegate, fuel pump, dump pipe, hi flow cat, 3.5" exhaust, radiator etc

My suggestions would be For around 240 to 250 rwkw, ball bearing hi flow your standard turbo.  Plus a split dump, 3" exhaust, Tomei 256 Poncams, POD with heat shield and CAI, Power FC ECU with boost control kit, standard GTR fuel pump and a standard GTR intercooler.  That's about $10K worth.

For 300 rwkw simply double the cost.  If you want to spend $20K then I can give you the list for that in another post.

Hope that helps

I agree and disagree with some of this sydneykid. I'm making 253kw @ rear wheels. I had my stock injectors taken out, cleaned and then tested for flow to make sure they were up to the task and then put back in. With a bosch 910 fuel pump upping the pressure the stock injectors are only at 70% of their flow (another car is making 274kw @ wheels with the same injectors, pump and a fuel reg and it seems it still has a bit of headroom left). I cant make anymore power until I change the exhaust manifold as that is holding up my flow badly now so I agree with that point.

[r34nismo]

i ran out of ECU map at .85 bar running different intercooler i was getting 0 degree retartdation.

[Guest INASNT]

Originally posted by r34nismo

i ran out of ECU map at .85 bar running different intercooler i was getting 0 degree retartdation.

wtf does that have to do with the price of fish??

Adzmax

u should drive your car and get used to it before considering upgrading it!! Has it landed in Australia yet?

[Guest RedLineGTR]

as inasnt stated give the car abit of a drive before u start playing with the turbo..get the mods on and shit...leave the turbo till last..dont know if its the best thing but for a turbo upgrade maybe hiflow the stock one, or a 2530 abit small but spools up nice and will have u abuot at the 240 230rwkw mark. Your money man your choice.