R34 With Gcg Hiflow Problem

[bikey]

i recently got my turbo hiflowed by gcg, did the whole shebang, injectors,fuel pump, pfc etc..

took it for a tune at Unique, and it turns out that i cant hold boost. they swapped over a r33 gtst actuator and added tension, and according to them, there was a slight improvement holding boost.

they also patched in a profec b ebc, and upped the gain to max, and it held boost much better.

from the graph, you can see:

on high boost, 18psi drops to ~13.2psi

on low boost, 13psi drops to 10 psi

the guys at unique cant figure it out (im sure they would eventually, but i cant afford to keep dishing out money )

so im looking for some insight/experiences someone might be able to share.

atm, im looking to upgrade the actuator to a hks adjustable, and also looking into putting in a avcr boost controller.(currently have a dual stage turbo xs boost cont.)

but if i can get some advice before doing that, i can spare myself some cash!!

what do you reckon??

Edited November 22, 2007 by bikey

[MANWHORE]

The hks actuator will not provide you with anything that the profec b won't handle. Not at 18 psi anyways.

Cars i've worked on using the usual standard actuator + avcr or profeb b, etc etc all can usually easily hold 18 psi flat.

There is some other problem.

This may sound silly, but try dropping the exhaust. I.e. just run the turbo straight out into the air.

[MANWHORE]

Also, unless if I have missed it, are you running a fmic?

[bikey]

This may sound silly, but try dropping the exhaust. I.e. just run the turbo straight out into the air.

the exhaust heat is too hot... can you imagine the heat generated in the engine bay? lol plus, i dont think any workshops will let me. (ive asked a few)

btw, ive got a split dump pipe running 3 inches throught the front, cat, catback...

and yes, got a Trust FMIC happening...

Edited November 22, 2007 by bikey

[MANWHORE]

Ok, another option that i've seen with some gcg highflows and other highflows - the catridge is shorter, which means that the wastegate flapper leaks. But i'm guessing that unique already checked this - when you said that they added tension (by bending the rod)

[SECURITY]

his exhaust isnt restrictive. its got a trust front pipe, hiflow cat and a 3" cat back. his exhaust flows.

its just that on the dyno whenever its given a boot, no matter if its on high boost or low boost it loses around 4psi.

i was having a read about the GCG turbos, when they weld on the wastegate they weld it on with the wrong angle so when you put your wastegate actuator on it makes the wastegate flap open slightly. thats why the extra preload (tension on the wastegate arm) would have helped.

ive got a similar problem with my gcg hiflow and ill be putting a bit of extra preload by bending the actuator arm a bit.

manwh0re, i reckon you should try this too if your turbo isnt stuffed. i remember you telling me that you used to start seeing boost at 4000rpm on your slide hiflow. it may be a similar fault.

[R31Nismoid]

It'll be the int gate leaking.

Heaps of them do it, there have porbably been a dozen threads on it now.

Just adjust the gate so its 110% shut at idle via some more preload and you'll be ok.

[Dale FZ1]

Look at eliminating the cat as a restriction point.

$30-40 should see a 3 inch pipe with flanges welded up, and then you're not wasting workshop time and paying more $$ dropping pipes off etc.

If you do a search under a thread by Al, you will find he experienced some high flow performance issues that ended up being exhaust system related.

FWIW, the graphs themselves look quite respectable at the boost levels being achieved (namely dropping).

[R33GOD]

my boost wasnt holding well either on my hiflow. it would only hold 16 max. thats with the hks actuator and all.

my turbo crapped itself 3 weeks later.. hmmmmm

[MANWHORE]

his exhaust isnt restrictive. its got a trust front pipe, hiflow cat and a 3" cat back. his exhaust flows.

its just that on the dyno whenever its given a boot, no matter if its on high boost or low boost it loses around 4psi.

i was having a read about the GCG turbos, when they weld on the wastegate they weld it on with the wrong angle so when you put your wastegate actuator on it makes the wastegate flap open slightly. thats why the extra preload (tension on the wastegate arm) would have helped.

ive got a similar problem with my gcg hiflow and ill be putting a bit of extra preload by bending the actuator arm a bit.

manwh0re, i reckon you should try this too if your turbo isnt stuffed. i remember you telling me that you used to start seeing boost at 4000rpm on your slide hiflow. it may be a similar fault.

Joe, already did it from the start

[Tangles]

very similar with my slide highflow

I ended up using a cheap 3rdhand GFB stealthFX plumback BOV (helped a little IMO) and awaiting my HKS heavy duty actuator from Nengun, who certainly arnt in any sort of rush to post it out to me

Im hoping the actuator will help me hold the boost better than what it was when tuned.

[SECURITY]

Joe, already did it from the start

did it work?

[Dose Pipe Sutututu]

Is your intake the factory rubber one? perhaps its sucking closed on boost ??

And don't waste your money on fully sick boost controllers, just get yoursself a turbotech one, doesn't spike etc..

I'm using one and it holds 16PSI all day lonng

[MANWHORE]

did it work?

No, the rpm I quoted was after doing that.

[r32sky_line]

I agree with johnnilicte, the factory rubber inlet is probaly sucking closed on boost.

[666DAN]

I bet the following doesn't help, but can't wait to see you solve the issue

-Exhaust change

-CAT change

-HKS actuator (massive preload)

-Silicone Intake pipe

-Gyspy tears

[RB30-POWER]

i'll put it down to the hot side being to restrictive, causing high back pressure on the manifold side of the turbo and forcing open the wastegate.

how much power do you think can be put through an op6 turbine housing, its designed for standard power, sure the highflow wheel will help, but only so far. if you want every last bit possible, get it power ported as well.

a 1 bar actuator might help a bit, but that will become your lowest possible boost setting remember.

[OVADRV]

hi bikey i had the same issue with my boost dropping at high revs on my high flow ,tuners were stumped until i saw the rubber intake pipe sucking close at high revs, read this it has solved my problem

http://www.skylinesaustralia.com/forums/Lo...87#entry3458787

Edited November 24, 2007 by OVADRV

[666DAN]

I hope to hell that's your issue, cause it gets very old and frustrating if it's the exhaust housing on the turbo that's giving you grief.

[32vspecII]

had same problem with slide performance stage 3 hiflow

swapped for hks gtrs and holds boost perfectly at 1.4 bar

everything else was identical , exhaust , intake etc

i personally suspect turbine housing but I am no expert