Hks Gtrs On Rb20

[tp1gts2]

i decided to put my car on the dyno to see how much power it had.

mods are

standard rb20

gtrs turbo

power fc

550cc injectors

cooling pro fmic

3" exhaust turbo back

do you think my gtrs should make more boost earlier than this?

i have a turbotech bleed valve on the hks adjustable actuator. can i just run the actuator by itself without the bleed valve? what would be better?

here are the air/fuel graph and torque graph

im interested on hearing your opinion's as im not right up with this kind of stuff

[PM-R33]

Max boost at 6000ish rpm? That doesn't seem right man. Best bet, put the car back on the dyno, wire the wastegate flap shut and see how quickly it ramps up boost, if it hits full boost a lot earlier than most likely your wastegate is opening a bit early and leaking off exhaust gases. Maybe invest in an electronic boost controller if thats the case to try and hold the gate shut.

[Roy]

What state are you in? How well do you know your tuner. On the face of things there is something masively wrong with the results you are getting. It could be tune, it could be boost control, could be the CAS. It could be a collapsed catalytic converter.

Could be lots of things, but i would assume your tuner would have given you some feedback on wht you are makign so little power from a 450hp turbo running that amount of boost, and why it is so slow to build boost

[GtstCoupe]

Definalty check your Gate and Controller.

[Adz]

It is a big turbo for a 20. But yeah id keep checking.

[abu]

interloper runs a GTRS turbo on his RB20 and he was getting full boost around the same time as my HKS2535, both internally standard RB20 motors

Maybe send him a PM and he will be able to give you some more details since he has first hand experience

Oh and I was getting around 18psi by 4,000rpm if I remember correctly, thats with HKS cam gears though

[116.hks]

hey mate. i had a plan bearing precisions turbo gt37 on my stock rb20 and made boost abit earlier then u have and i made 280hp on 11psi. check to make sure the exhaust is not blocked e.g. cat's not collapsed.

[limpus]

Something is definitely wrong there looking at those graphs...i'd give everything a once over...check for restrictions and leaks all over...perhaps have a look at the wastegate actuator too...GTRSs come with adjustable wastegate actuators yeah? if so i'd start there...

[nizmonut]

280 hp is 208 kw, give or take the variance in the dyno and there pretty much the same out put.

you two chould go to the strip, be a close race.

[tp1gts2]

thanks alot guys!

last night i took the bleed valve off and put the line from the front of the turbo straight to the actuator, went for a run, it didnt change a thing, it weas exactly the same as before.

just then i wired the actuator shut, went for a spin, boost up heaps earlyer about 4500 by the looks of it.

so what does this mean? is my actuator falty?

my line is picked up off the nipple on the front compressor housing like the stock rb20 turbo was, then straight to the actuator

what do i do next? replace the actuator?

thanks alot guys, you've been a heap of help

[Adriano]

Adjust the actuator, give it a bit more preload, and see what the results are

[tp1gts2]

well, ive just adjusted the actuator shaft as far as i could in(shorter about 10mm) that should preload it right?

took it for a drive like that and it still boost's to 18psi and does it slowly like on the dyno graph

mates are putting the pressure on to go external gate, i want to hold off on that in case there is a easy fix for this actuator

[PM-R33]

Hmm so for some reason the actuator is pushing the gate open and leaking off exhaust gases. What dump pipe you running?

[tp1gts2]

im running one of the jjr split exhaust/wastegate front and dump pipes

it cant be the cat converter as there isnt one, and there is no mufflers so i cant see the exhaust being restrictive

and its perfectly ok to pick my pressure line for the actuator up from the nipple on the compressor housing?

Edited July 30, 2008 by tp1gts2

[PM-R33]

Yeah mine is on the same spot man so thats cool.

There's two things that i could think of that may narrow it down a bit more.

a) If you can borrow a dump pipe off of some one that is an all in one bellmouth pipe and not a split dump pipe. I had dramas with my split dump pipe and went to an all in one bellmouth one. I remember reading some where that some people have had their wastegate flap "pulled" open by a vacuum caused in the pipe from the wastegate by the exhaust gases flowing past it down near the cat when the wastegate is shut. It's a long shot but you never know.

b) Try an electronic boost controller and see if it can keep the wastegate shut. Have a look for Trents (URAS) thread from a couple of days ago about electronic boost controllers, kind of explains a bit there.

Other than that it seems to be a faulty actuator that has lost its spring pressure or something and is opening the wastegate early. Did you buy the kit new or second hand?

[tp1gts2]

so... my cheapest option would be to chop the wastegate pipe off screamer spec and block the hole left in the exhaust?

other than that going external gate with the stock manifold might be a idea, what size gate would i need for this?

the kit is brand new, had to wait ages for it to get made

the whole idea of my dyno run was because ive got a plazmaman plenum on the way and wanted to see how much difference it makes, glad i done it now, should go heaps better with proper boost and the plenum haha

thanks alot PM-R33, you might be on to something there

[discopotato03]

Have you tried screwing some extra low and part load ignition advance into your RB20's PFC ?

The std Hitachi RB20 turbine housing and turbine are much more restrictive than the HKS turbine housing and Garrett turbine wheel .

I'd be looking into this first , cheers A .

[Roy]

Before changing hardware i would be talking to your tuner. Having tuned it he should have a feel for why it isnt performing as expected. It coul dbe the tune, it could be the fact he is scared of pushing any more because of the perceived condition of the engine...it could be he simply lacks the talent to tune the thing...Or it could be something mechanical

[bluer_32]

im running one of the jjr split exhaust/wastegate front and dump pipes

it cant be the cat converter as there isnt one, and there is no mufflers so i cant see the exhaust being restrictive

and its perfectly ok to pick my pressure line for the actuator up from the nipple on the compressor housing?

From memory the JJR split dump pipe has a seperator plate that is designed to protrude into the cavity if the standard turbo's exhaust housing to keep the gases of the wastegate seperate, you would of had to grind that bit off to fit if the GTRS came with a HKS T3 exhaust housing i would presume, the wastegate flap on the HKS exhaust housing protrudes further than the standard one, therefore it may be hitting metal and not opening fully, the proper HKS dump pipe is designed to allow for this, (see pic)

I would bet that dump pipe is contributing to your problems.

[NWR31]

i may have the wrong end of the stick here, but if the flap is not opening enough it will cause higher boost/boost creep & his issue is the opposite.

could be possible the flap is hitting something & not closing properly i spose

Edited July 31, 2008 by norwest_rumbler