HKS Turbo

[4 Doorz]

Or all you guys done twin turbo conversions on your rb25's?

[EVOIV]

I am pretty sure that twin GT2530s are much bigger than a single GT2835. 2 x GT2530s are more likely equivalent to a single GT3240. But yes, a single GT2530 is TINY for the RB25. A good choice for the GT2835, although I would be tempted to go the GT3037S

[Turbo Tits]

HKS GT2530's are not at all too small for RB25's... on what info and prior experience are you guys basing this comment on? for those with only moderate power ambitions, this turbo on the RB25 is capable of making considerably more power over the standard item, spooling at almost identical RPM to standard and with its steel exhaust turbine can support increased boost pressure. having bought one myself, ive done the research. i have all the support systems and will be installing once the car comes back from the painters. i will be happy to post dyno charts for those who are more sceptical. btw, the HKS manual that came with the turbo kit has an application chart on the front cover, where the RB25DET in clearly mentioned. i think they should know.

[EVOIV]

I am only guessing that a GT2530 would be too small for a RB25. If you say that this turbo can make upto 230kW@wheels on a RB25, then that is only a minor upgrade from the stock turbo as can't the stock turbo produce near 200kw@wheels already? Maybe even more? Once again, only a guess as I'm not a skyline owner.

From personal experience, I used to run a GT3037S (56T) rated at 480PS on my EVO4 (2L). It was laggy, with boost coming on at around 3500rpm. But on a 2.5L, I would expect lag to be produced at 3000rpm, or maybe even earlier? I know that a 3037S on a 2L can produce up to 300kw@wheels, or so I've read in many places.

[Freebaggin]

Agree with Turbo Tits, 2530 on RB25 would be a very reponsive package capable of 220rwkW for sure.

Also hardly anyone does twin turbo conversions on RB25, there is no advantage doing it.

[EVOIV]

Responsive, yes...not much gain though. For small upgrade, the 2530 may be good, for moderate I'd go the 2835 or larger. So for a 2L engine, what would be the equivalent turbo? The 2510? That's the smallest turbo HKS make isn't it? Or smaller?

[franks]

evoiv you're correct when you say its probably not worth it to get a 2530 when you're realistically only gaining 50kw on top of a standard turbo.

but having that said, i am on the same notion as turbotits...i only want 230 or 240rwkw because i want to:

a) keep it highly responsive

B) i think anymore power in a rear wheel drive, whilst being utterly fun, is utterly pointless! traction would be an absolute joke.

c) whilst its only potentially a 50kw gain on a standard turbo, you know reliability at this level is far greater than that of a standard turbo.

[DoughBoy]

I dunno, seems like alot of people want a Mac truck turbo capable of flowing 5,000 lbs of air at 1,000 rpm shaft speed.

2530 has incredible throttle response, only place it really loses out is above 150km/h - how often are you going to be doing that?

[EVOIV]

The 2530 is a very responsive turbo, but after a while a small turbo car just feels like an ordinary car with more power. Whereas a larger laggier turbo car has less power off boost, then the power really surges and you can feel it all the way to max boost. It's a totally different experience. But a smaller turbo car will feel faster on the street, because there is less lag. I guess what I'm saying is it depends whether you like linear power or a peaky power curve.

[ex_zero]

how is it like to have 200rwkw power on the street anyway?

[SLY33]

my car currently reels off 199rwkw at 12psi with std turbo. This power sounds insignificant when seeing all these 300rwkw monsters. BUT the reality is that my car with "only" 200 rwkw is a pretty mean street car! being in adelaide, most of the speed limits are pretty low, so i only really drag up to maybe 150kmph tops around the city (late at night!). 1st gear cannot be fully used even at 200rwkw due to loss of traction, and any more power would make 2nd gear pretty much the same.

As a direct comparison to bigger turbos, ive run big external gate turbos on the street, and honestly, they suck 0-100. I murder them off the line (no one exactly runs nittos around here!) and by 120k's im on the brakes already, race over, and won! being in a 60 zone why would i want to run any faster than this? -its when im finished and on the brakes that these things come screaming past with ext gate barking. I cant see the point in a "pure" street car unless you have super traction, or slicks on the strip.

ex-zero, in my opinion 200rwkw should be enough for most on the street!

that all said, im also getting a 2530. As im running std internals, i dont want or need power over 250rwkw, plus what hasnt been mentioned is that while the 2530 only offers some 30rwkw PEAK power, the torque factor needs to be considered. From what ive been told the small HKS will give me significantly improved torque where i need it.

[SLY33]

btw not bagging big turbos, they obviously have their place and would be awesome fun, but on the street i would say its more about having a punchy, usable, and reliable package, and that a quick street car is certainly not defined by its peak power, but by its average power (ie the GT2530 might make less peak power, but more "average" power -and hence be quicker- than something bigger that has a higher peak figure.)

[EVOIV]

I used to have over 200kw@wheels on an AWD 2L and I never broke traction changing through the gears, but it's AWD I guess. I can't say I've driven an equivelant powered car in RWD. Interesting post (above). That does seem a fair comment for a street car and street drags. But if you are thinking of going to the drags, then I don't think it'll cut it. A GT2530 is way too small and I am guessing on an RB25 the car will probably run high 12s? At best. All depends on the application: street, street & occasional drag, street & occasional drift, full drag, full drift...etc.

[EVOIV]

I agree that for street a responsive turbo is better suited, and laggy peaky turbos aren't as great in a street drag. But I was just thinking that a GT2530 is a little too small, why not the GT2835? It will be laggier, but have more top end. But then I don't know HOW much laggier it is?? Is there a GT2830?

[EVOIV]

If you're going to stick with your standard internals, it would be better to go for a Garrett GT25 series turbo over the HKS GT2530. Reasons being: The Garrett is cheaper, and Garrett turbos are more efficient at around 1.0bar whereas the HKS turbos are more efficient at around 1.5bar. If you've got standard internals, you won't be running much more than 1.0bar. HKS turbos are only particulary good when running high boost with forged internals.

[ex_zero]

will the Garrett GT25 series turbos have the same punch as the equivalent HKS turbo? i.e. in the midrange, would both turbos be making the same sort of power?

e.g. a Garrett GT25 turbo similar to a HKS GT2530, running 1.0 bar boost, running against a HKS GT2530, at 1.5 bar of boost, which would make more midrange grunt?

[EVOIV]

A Garrett GT25 at 1.0bar boost will produce less torque/power as an HKS GT2530 at 1.5bar boost. There is a difference between power and efficiency. What I meant was that both turbos at 1.0bar, the Garrett would probably produce more as it is more efficient in that range of boost. At 1.5bar, the HKS would produce more power than the Garrett at 1.5bar as the HKS is more efficient at that boost range. It depends how much boost you want to run. Both turbos are efficient at different levels of boost.

[ex_zero]

ahhh, right ok, get ya now

[SLY33]

there are people on both sides of the fence. Some say with HKS your just buying the name and that equivalent garrets will perform the same at cheaper cost, where as others will say "you simply wont get HKS numbers using garret stuff" (quoting martin donnon). I dont think its worth getting into unless we have a member who has done a back to back turbo comparison on the same engine. Otherwise this thread will just be pages of back and forth arguments, which is a waste of time if a conclusion is not met!

evoiv, i plan to run 1.1 bar at first and hope to get around 230rwkw (its been done many times on RB's, showing you dont really need to run 1.5bar boost to get good power), then later on if i desire more power, change head gasket to drop compression (and inspect the tops of pistons and bores for condition while the head is off) and run maybe 1.3 bar.

std turbo's are capable of high 12's, so i would hope to see mid 12's if traction can be achieved.

dont take this the wrong way im not having a go at you evo, but it doesnt sound like you have any RB or skyline experience and are throwing down info on turbos that you dont really know about! It is well proven that a GT2530 is an excellent upgrade for an RB25. Evo's are awesom, but are very different horses for very differnt courses (compared to our RWD RB's)

[SLY33]

ex-zero, if you can wait a couple of months, ill have my car up in sydney with the HKS GT2530 fitted and tuned, ill take you for a spin and you can make your own opinion first hand.