GT2530 results update

[SLY33]

Id been having trouble holding boost, and bought a new wastegate actuator. When i went to remove the stock one, i found that even with the actuator rod fully in, the wastegate was actually about half a mm open!

Installed the new actuator, putting plenty of pretension on it so the gate was held firmly closed.

Fired it up and went for a spin. Once warm i gave it a 3/4 squeeze in 2nd from about 40km/h, the thing came on boost like never before and snaked beautifully up the road! I then realised that i hadnt changed my EBC settings, still set for the old actuator, and that i had just experienced 1.45bar! oops! but knock levels were well under 20 so i wasnt too worried. I adjusted the EBC and set between 1.2-1.3bar.

The car was now feeling better and crisper than ever, and was holding boost longer, but still falling to just under 1bar at the very top end.

Off to Morpowa for another tidy up tune, i was expecting good results.

This being the third tune so far, produced even LESS peak power, at 218rwkw. What had i done? I'd fitted a hiflow cat since the last tune, and it literally killed top end power. When having the cat fitted i was told id lose a few rwkw at most, but after seeing the power result i rang Exh Tech and was told that with the boost and turbo im running, it would easily cost me 10rwkw or so.

But after driving the car after this final tune, the peak power didnt bother me at all, as the car is by far the quickest its ever been. It now pulls like it did when i ran 1.4bar boost, lighting up second beautifully on a boosting roll on! Put it this way, if i was told that the car made 235rwkw id have believed it. (the original tune made 227 and it feels quicker now)

Just for curiosity's sake, i pulled the new cat for a test on a private road. Immediate obvious seat of pants difference. Spool up is noticably even quicker, especially in 3rd and 4th. It feels very fast but i couldnt rev it out, as i hit 100% inj duty cycle pretty much immediately after boosting!

I already have injectors on the way. Needless to say i will be exploring a "super" hi-flow cat option (some sort of custom arrangement) and when the new injectors go in we'll see how she goes.

As for the boost not holding to get a good peak power, ATS says its because the RB25 at 1.2-1.3bar creates too much exh flow through the turbine, which spins the compressor out of its efficiency range, and instead of pumping/compressing the air, it "chops" it, and causes boost to fall off. This problem is not apparent on an RB20. So i guess it could be said that this turbo is too small for an RB25, which i have argued in the past, but damn the thing is so punchy and torquey through the midrange, that on the street it is more than suitable.

the perfect example is the red 300zx i ran last night, he had 250rwkw vs my 218rwkw. I ate him, shifting at 6000rpm. If thats not a perfect example of how midrange torque and "AVERAGE" power is more important than "PEAK" power, then i dont know what is!

Overall very happy with this turbo, and i'm still confident that with a less restrictive exhaust, i hope to see easily over 230kw at the wheels.

[Ronin]

:headbang:

Sounds nice. I'm thinking of getting a 2530 for my r32, but i'm teh broke at the moment. What did the turbo setup cost you?

[Guest Robo's]

Nice, keep us posted

[knore]

So putting a Hiflow cat on made you loose power? That cant be right, is it a 3" high flow cat?

Im interested in how much it was too, what other mods have u got?

[Ronin]

A cat will always make you lose power, its a restriction.

[EnricoPalazzo]

of course puttin a cat on would loose power.

[rb20-calais]

i might get my cat done so its a 3" pipe through it, I am getting my car tuned atm with the hks 2530 on rb20

evan

[SLY33]

knore, when i bought the car it had a gutted cat. I replaced this with a new 3in hiflow cat. It just proved to be more restrictive than i thought. The car has all the usual basic bolt on mods. Exh, CAI and pod, FMIC, fuel pump, FC, clutch, EBC etc etc plus 2 way diff and upgraded brakes.

the turbo setup cost me $1800 + a few braided lines i had to get, so all up under 2grand. (also 170 or so for a tomei fuel pres reg as using std injectors)

Had some runs tonight against a GTR with twin GT2530's (you know who you are!). Off the line of course no chance, rolling run also of course no chance, but i was surprised how well the car hung in there, and i think so was he! Also played with a jap spec STi WRX running 1.8bar and possibly a bigger turbo. Wasnt even going to try off the line, but rolling run, see ya later!

[Steve]

sounds nice Sly, shame the cat is hurting. I saw a comparison in '21st Century Performance' a book by Julain Edgar, and he came to the same conclusion as you - high flow cats dont flow that high.

will be good to see the results with a higher flow cat fitted. What ATS are describing to you is compressor surge, which is a pretty violent sort of thing to happen, and would be accompanied with violent boost fluctuations and a feeling that the car is hesitating/loosing power? is that what you are getting, or am I missing something?

congrats again, the R&D, whilst consuming time and money, can be pretty rewarding - and if nothing else, helps others going down a similar path to you:)

[N/A®]

Thats some amazing story about the actuators. I might get a set from HKS just to see. Not expensive anyway. They are all the same right? No specific models to get.

We should go looking for more runs next time Take u for a spin next time. :headspin:

Btw, next time ill make sure we match boost for boost. As u know, those GT turbos are only efficient after 1 bar! Youll be suprised what mine does at 1.2bar.

[SLY33]

hi steve! yeah shame about the cat, if hiflows are this restrictive id hate to see a normal non-hiflow cat! I dont get compressor surge, which is where the compressor tries to pump more air than the engine can swallow. From what Bill from ATS said its a problem with the comp wheel spinning out of efficiency and losing ability to pump. I dont think the wheel on a 2530 is big enough to cause comp surge.

Im actually surprised at the amount of R&D that im forced to do! I thought that with all the tuning places around doing these cars nowdays that they would pretty much have a full understanding of these little "mystery" problems such as ive had/having, and ended up costing me much more than i budgeted for! But it definitely helps those who want to go the same road!

N/A, yeah i know, they go sick after 1 bar! I can imagine it would be like a jet!

[knore]

Was $1800 brand new?

Im thinking about going the turbo upgrade for my rb25, either 2530 or 2835

I want something thats a good jump in power, but its not that big i need to upgrade internals or wait till 5000rpm to hit good boost.

Whered you buy it from?

[Guest Robo's]

I like it too, with a straight bolt in and out procedure and no high mount turbo.

Imagine getting pulled over by a cop with a high mount

[RBSleepR]

Sly, a "super" high flow is basically a straight thru pipe in a cat housing with no internals - sounds like that's where you started b4 u put on the high flow cat .

If the engine needs to breathe, u will usually see about 10kw difference between a straight thru and a high flow

Don't know much about RB25's, but u could be right that 2530 is too small - hence exhaust flow problems

lets face it, 2x 2530's on RB26 is magic for 300 - 350 kw applications

good luck with the continuing developments - sounds like u need those bigger injectors :-)

[DJ_L3ThAL]

i have been tending more towards a 2530 myself now too as i wanna keep motor stock, so i think going fuel pump, injectors and a 2530 would be the go in my case, do you guys think 230rwkw is obtainable with a pwoerfc trust fornt mount full exhaust and EBC is obtainable with a 2530 on a 33 using the standard AFM too ? or would i need a Z32 ?

[knore]

A descent 2530 setup will make about 250rwkw

Im thinking more along the lines of 2835, its a little bit bigger, not too much .. just right

[Guest Robo's]

250 rwkw would be awesome

[N/A®]

Sly is it a HKS unit or a garret one? Im thinking 2540 for the 34. Majority of the tuning shops in japan recommend 2530 for GTR but 2540 for RB25. Must say something for the topend.

See u on the streets.

[king_kw13]

Hey Sly33 - do u think u could post some dyno tune graphs of the 2530 in action? I want to see how hard the turbo kicks in when its on boost.

[knore]

250 rwkw would be awesome

For sure

And with the right things in the other areas, you should be able to pull some constant 12sec passes