HKS GT2540s for GTR...how laggy?

[BoOsTeD_RB26]

Just as the topic states,

I'm really close to purchasing a pair of GT2540s, but the only thing I have to ask is are they really that laggy? There has been much speculation on these turbos about how they are too laggy and the 2530 is the way to go?

The car is a street car but surely the 2540 can't be that bad considering the 2530 and the 2540 share the same size exhaust wheel.

When could I expect full boost considering that a standard GTR will be around 4000rpm???

Can anyone shed some light?

Thanks

[gtr13]

Whats full boost? i have HKS 2540's on my R33 GTR hits 1 bar at around 4800rpm 1.5 bar at around the 5600 to 5700 it all depends what your used to im told 2530's are usually around 800 to 1000 rpm less laggy. The 2540 are meant to run slightly more boost then the 2530 that said mine are normally on 1 bar which iam quite happy with on the street, i dont think there as bad as what every one makes out . Another thing i find is when driving on the street iam not always on boost where as with the 2530's it might be a problem as far as police or fuel consumption is concerned. But if you want it for a circuit car go the 2530's but for the odd drag event or dyno comp the 2540's.

My car also has standard cams and manifold only have the HKS dump pipes so iam looking at getting cams and some work done to the heads and maybe a 2.8 ltr kit down the track which will help it come on boost alot quicker. At 1.3 bar the car was dynoed with 320 rwkw and has run an 11.4 qtr .

[BoOsTeD_RB26]

so for the street, are they alright?

I am used to my car (with stock turbos) to hit 1 bar at around 4500rpm.....so the 2540s are not much worse than that?

I just dont want to fork out for these and the car turn into a pig to drive on the street as the car is a daily driver.

Thanks for ur help

[gtr13]

PM sent

[BoOsTeD_RB26]

Check ur PM again

[Sydneykid]

Hi BoOsTeD_RB26, we had 2530's on our GTR and took them off and installed 2540's, we wanted just a bit more power. Very bad move, couldn't wait to get them off, and I know of 3 others with the same opinion.. The 2530's were much more responsive and the average power from 4,000 rpm to 8,000 rpm was higher with the 2530's. For an all round usage GTR for street, strip and track I can't think of anything better than a pair of 2530's. The N1's come pretty close though.

Hope that helps

[whytry]

if you guys thought the 2540's were laggy you should try the 2540R's even more laggy and top end is awesome.(an extra 20-30hp more)

although the new HKS GTR-S would be perfect, with the midrange+response of the 2530's but with the top end to match the 2540's. i personally think the GTR-S are the best turbo's (for low mount that is) HKS have made. they are rated at 400ps, so strap 2 of the buggers on and hold on, just don't forget to tune and upgrade the fuel system.

otherwise if you still want the 2540's, just add stage 2 cams (HKS, TOMEI, etc) + adjustable cam gears a little bit of head work (port, polish+same on exhaust side port+polish) it'll help boost the 2540's up nice.

or add say 50hp nitrious system and forget what i just mentioned above.

:)

[Sydneykid]

Hi whytry and others, following are the dimensions and trims of the range of HKS turbos in this area;

.....................Compressor......................Turbine

....................Trim...Inducer....Exducer...Exducer...Inducer....Trim

GT2530..........63____1.860____2.344___1.883____2.098____76

GTRS.............52____1.997____2.773___1.833____2.098____76

GT2835..........52____1.997____2.773___2.020____2.204____84

GT2540..........46____2.016____2.972___1.833____2.098____76

As you can see the GTRS is merely a 2835 compressor (and cover)with a 2530/40 turbine (and cover). In my opinion, supported by experiences, the 2540 is badly mismatched between compressor and turbine (ie; either the turbine is too small or the compressor is too big). This why they have good top end power but are very slow to get there, particularly on a 2.6 litre engine. A bit better on a 3.1 litre, but not enough to account for the restriction from the smaller turbine.

It is my belief that HKS recognised their mistake with the 2540 and introduced the GTRS to fill the gap created by this failure.

To achieve this they have simply used a 2835 compressor with a 2830/40 turbine. BTW if you wanted to upgrade your 2530/40 to GTRS it is simply a matter of buying a 2835 compressor and having the 2530 cover machined to suite or, in the case of, 2540, buying a 2835 cover.

So now let's get to the question of GTRS producing more top end power than a 2540. I simply don't see how that is possible, the turbine is the same size, so no power advantage there. The compressor is smaller, so definitely no advantage there either. The only way I can see a GTRS producing more top end power than a 2540 is by using higher shaft RPM to create more boost. But it is still going to tip over the efficiency hump (make air hot) same as a 2835. So to take any advantage of it you are going to need a bigger intercooler.

Me, I'll stick with the 2530's on the 2.5, 2.6 & 2.7 litre engines and 2835's on 3.0 & 3.1 litre engines.

Hope that explains my position a little better

[DoughBoy]

What about the GT-SS turbos? Had any experience with them?

[Sydneykid]

Sorry DoughBoy, I haven't measured a GTSS. In fact I can't say as I have even seen one. But you can bet it will be another HKS "mixed bag of Garrett bits". They will pick a different combo and make reasonably valid claims for its performance.

But until they move up to the current generation of turbo technology, that's about the best they can do to generate publicity. Launching a "new" product always guarantees publicity from the "lateast is greatest" magazines and keeps the cash register ticking over.

That's business.........

[Freebaggin]

Sydneykid,

You mention, ..."until they (HKS) move up to current generation turbo technology"..., does that mean other manufacturers are using newer generation turbo tech. than HKS?

Who are they? Is for example a GT30/40 CHRA from Garrett current gen. tech.?

Cheers,

Freebaggin

[Sydneykid]

Hi Freebaggin, I think the Evo VIII N1 turbo is pretty much current generation.