HKS GT2535 - Optimum efficiency band ?

[BigDatto]

Hi everybody,

Are there any gurus here who can tell me the peak efficiency band of this particular unit ?? Steve, I'm told you have an honorary Degree from HKS University for voluntary community services ??

On the HKS site they rate all GT25xx's power outputs at 1 bar. It's widely known that HKS compressor trims are more efficient at higher boost pressures. But I can't find diddly on this one

any help is sweet goodness !!

[SeriesIIGTST]

sorry to be the bearer of bad news but in general HKS do not publish their compressor maps for the general public. I don't believe you even get one when you buy the turbo new from HKS! It seems to be one of those moot points amongst purchasers of aftermarket turbos...

[Steve]

Sorry BigDatto, cant help with specifics, here is a link to comparison dynos for 2510, 2530, 2535 and 2540 :http://www.hks-power.co.jp/products/turbo/...c_gt/ac_gt.html

might find it interesting. The 2510s on there are tested at 1.2bar, the 2535 though at 1 bar.

I think you may find it will vary for each car/engine, depending on setup. things like cams, porting, exhaust etc all seem to have an impact on where optimum boost pressure will be.

When the car is on the dyno, just keep turning up the wick until the returns are minimal for the increase in boost. Grepins 2835, when originally tuned used 1.65bar, as that was where it was producing optimal returns. He found boost leak, fixed that, now he finds 1.3bar is optimal. I was running 1.7bar, after changing exhaust, I am running around 21-22 psi. I know another guy who was running a 3037 on SR20, he found optimal boost was around 1.4bar, but was making the same sort of power that I had at 1.2bar on my RB25.

I would imagine there is an optimal boost pressure for each turbo in a perfect world, but my experience has been that there is no such thing as a perfect world.

Sorry I cant be of much help.

[BigDatto]

Guess I'll just have to suck it and see when it's fitted...

Thanks for your input guys.

[SLY33]

thats a cool link steve, i wish i saw it before i got my 2530! as it clearly shows a healthy 250kw produced by an rb25 with a 25"40", which is ideally what i should have got...!

Those dyno graphs are rear wheel kw right? if so then HKS rate their turbos in rear wheel PS. That is interesting, as lots of people bag rwkw claims made with these turbos by saying "well its only rated at 3xxPS at the engine, so it cant possibly be making a true xxxrwkw"

is that right?

[T0nyGTSt]

But SLY,

Look into what the general consensus is in regard to the 2540.

I do not believe they are as bad as people make them out to be but I do think they are perhaps a more 'hardcore' turbo which needs cams to restore the same driveability.

T.

[Steve]

SLY33, not really sure how HKS rate their turbos, except that I have heard from a few souces that the power quoted on their turbo comparison charts are based on the turbo alone, ie, their compressor maps (that they wont release), and are 10% lower than what the turbos actually make.

This is where it gets confusing, as they are rated at 1 bar (on the turbo chart) so it is hard to tell what they will do when you turn the wick up. Fortuneately most of their turbos have been around long enough that it isnt too hard to find real world figures of what people can achieve with the right support systems.

I think if you were chasing around 250rwkw, the 2835 would be a better choice than the 2540. grepin is making 275 at 1.3bar, it comes on boost quite early and is very responsive.

Even my 3037, with a 0.61 turbine housing was making 256 at 1 bar, and hitting 1 bar at around 3000rpm. Just no good once you wind in any more than 1 bar boost, as with the small housing it would come on boost too easily and throw the back end sideways very easily - not good for traffic and meant I could only have 1 bar boost dialed in for daily driving.

The 2540 from every thing I have read, and all those I have spoken to concur that it is really only ok for drag applications, as it doesnt really do much lower in the revs - even in single form.

[BigDatto]

 Fortuneately most of their turbos have been around long enough that it isnt too hard to find real world figures of what people can achieve with the right support systems.

Unless you have a GT2535 and can't read/speak nihongo.

[Steve]

Well I havent heard anything bad about them (unlike 2540) so thats a good thing:)

[rbs13]

zoom were doin a thing on a commo and putting a rb20 in it with 2535.. they say its good for 250rwkw or 260rwkw.. prolly at 1.5 bar.. but i guess.. always pick a turbo that suits you.. hard to tell when not many ppl have these turbos etc.. but if your chasing 250rwkw and want a streetable set up.. id choose the smallest turbo that can produce that amount of power and boost level your happy with etc. but if you get bored.. the bigger turbo comes out better.. to be safe i think the 2835 would be a better choice.. run at 1bar.. be happy for 3-4 months. then turn the wick up and enjoy it more.. but then youd get to as far as you want to push that.. then you should pick the 3037.... oh here we go.. have fun.

[BigDatto]

That's some very cool info - thankyou.

I'm chasing a reliable 220-230@ the treads on an RB25, which is soon to get the Skylinegeoff rebuild, in accordance with Jedi Master Sydneykid's prophecy for a club/streeter that won't terrify the neighbours and the missus can drive.

So I reckons this turbo should be the mutt's nuts for response & squirt on 2.5L with the .64A/R turbine.

Steve didn't your GT3037S have the same housing ?? Where did it run out of puff ??

I'll post some findings when it comes together.

[treads]

HKS turbos are very good turbos thats why your paying the price for them and they work better on more boost for 250atw the 25/30 is good enough as it has hid and high end torque the bigger u go the more mid range you'll start to loose

[Steve]

BigDatto, I had the 0.61, but that was on the 3037, so the exhaust wheel would be a bit larger. It should come on boost pretty hard - too much so with the 3037, but should be great with a 2535.

I didnt really try and see how far I could push the 0.61, it was tuned to 256 at 1 bar, and at 1.2bar it was unstreetable due to how hard the boost hit. With the 0.87 housing that I have now, it made 270 at 1.1 bar and 285 at 1.2 bar.

It will be interesting to find out how it goes, I just hope when you fit it you dont expose other problems, such as I did. Became very frustrating, but it was very worth while now that its sorted.

[Fitzy]

hi all so do u think the 2540 is good for a race car circuit the car is never to be driven on the streets ur help would be great

Fitzy

[SLY33]

as shown in the link steve posted up the top, the HKS dyno graphs show the 2540 to really perform past 4000rpm, but loses out below that to the 2535. With cams to fill the midrange it looks like it could be a good street turbo, and im considering it as i like its top end, and my little 2530 strugles to get a good peak power figure!

[Trust33]

Hi everybody,

Are there any gurus here who can tell me the peak efficiency band of this particular unit ?? Steve, I'm told you have an honorary Degree from HKS University for voluntary community services ??

On the HKS site they rate all GT25xx's power outputs at 1 bar. It's widely known that HKS compressor trims are more efficient at higher boost pressures. But I can't find diddly on this one

any help is sweet goodness !!

Just curious big datto....How did it all pan out for you and the 2535???

[ix9]

yes!

Please enlighten us about the 2535!

[Trust33]

I think the last time he was on the forums was a couple of months ago.

[discopotato03]

Common fallacy . HKS do not make compressors or turbines , Garrett do theirs for them . HKS generally option the compressors with free flowing turbines so that the engine can have less exhaust restriction when operating in a pressurised environment . Always remember when our engine inhales more air to burn more fuel to make more HP it also puts out more exhaust , which has to get around the turbine .

[knore]

Common fallacy . HKS do not make compressors or turbines , Garrett do theirs for them . HKS generally option the compressors with free flowing turbines so that the engine can have less exhaust restriction when operating in a pressurised environment . Always remember when our engine inhales more air to burn more fuel to make more HP it also puts out more exhaust , which has to get around the turbine .

:werd: