Jump to content
SAU Community

Recommended Posts

hi guys, just wanting to bounce some questions off you guys, see if i can get any responses that could help my situation

ive got all the usual mods that SHOULD make mid - high 200's (rwkw) but i'm not getting there because the boost is not holding and my coilpacks are breaking down... now the coilpacks are an easy fix, but i dont know how to fix the boosting issue.

i'm looking for it to be running anything in the range of 17-19 psi... the boost quickly spikes to 17psi... but then drops immediatly to 12psi and holds there

i've had some people sugest its;

* the rubber intake shutting closed, and i need a metal intake pipe (even though ive done the rev210 mod)

* the std. bov leaking

* the wastegate actuator spring not strong enough (even though its supposed to be a 14psi actuator, and i've pulled as much preload out of it as possible)

* i need to run an electronic boost controller, because a turbotech just wont cut it

* my coilpacks are failing and breaking down at high rpm/boost levels (i have a new set of split fires on their way) and this will cause boost to drop off as engine is not getting full spark

for reference sake the turbo is a custom job from hypergear,

it's basically a 3076 squeazed into a std comp housing an aftermarket 0.63 turbine housing the breakdown of the turbo is as follows;

- standard r33 comp housing thats been machined out to accept a 76mm exducer in 52 trim, oil and water journal bearing CHRA, 0.63 rear housing with 68 trim and with 30mm internal wastegate hole, and a "high pressure" (14ish psi) actuator

does anyone have any idea other then those ideas listed above, why its not holding anything higher then 12psi?

Link to comment
https://www.sau.com.au/forums/topic/317106-not-holding-boost/
Share on other sites

To rule out the bov block it and see if it helps but should not leak at that boost.

I would go full metal intake because it could stil be geting shut on the stright part where you have not added the pipe into.

for a quick fix with the coil packs get some bcpres7s if your not already running them and gap it down low until it stops missing just to test it out.

Yes it would be better to run a ebc but I have seen the boost tees hold up just fine in high power aplications so I doubt it that so check for leaks aswell. I have a hypergear turbo aswell witha 0.63 rear and it drops off from 17.5 to about 15 at redline and thats with a 14psi acutator but yeah it should not be going to 12 like in your case.

i wouldn't stuff around with intakes if you've done the rev210 mod

even at .63 rear you won't get flat boost curve... Trent and i have tried heaps of different things. Swapped out BOV's, run i don't know how many actuators, i've got arguably the best aftermarket EBC, Blitz Spec-R, rev210 mod, etc etc.

Currently have such a beefy actuator in there at the moment that it runs 18psi with the Blitz turned off.

.63's will drop about 2-3psi at redline. That's just the way it is. And you'll find similar sized turbo's from HKS etc will have very similar boost curves.

You've probably got a few psi to pick up, but i still think at the end of the day, you'll get up to around 14psi at redline and that will be normal.

Do the splitfires, see how it goes, and then sus things out a bit further.

Also, i really don't think running 14psi at redline, after peaking at 17psi is really such a bad thing if your engine isn't built :D

How's doing the work/tuning?

i wouldn't stuff around with intakes if you've done the rev210 mod

even at .63 rear you won't get flat boost curve... Trent and i have tried heaps of different things. Swapped out BOV's, run i don't know how many actuators, i've got arguably the best aftermarket EBC, Blitz Spec-R, rev210 mod, etc etc.

Currently have such a beefy actuator in there at the moment that it runs 18psi with the Blitz turned off.

.63's will drop about 2-3psi at redline. That's just the way it is. And you'll find similar sized turbo's from HKS etc will have very similar boost curves.

You've probably got a few psi to pick up, but i still think at the end of the day, you'll get up to around 14psi at redline and that will be normal.

Do the splitfires, see how it goes, and then sus things out a bit further.

Also, i really don't think running 14psi at redline, after peaking at 17psi is really such a bad thing if your engine isn't built :D

How's doing the work/tuning?

Yeah thats correct you wont get flat but yeah around the 14 mark is what you will get at redline trent told me the same thing the 0.63 makes it drop down and as you said its not a bad thing to be a couple of psi down at redline

i wouldn't stuff around with intakes if you've done the rev210 mod

even at .63 rear you won't get flat boost curve... Trent and i have tried heaps of different things. Swapped out BOV's, run i don't know how many actuators, i've got arguably the best aftermarket EBC, Blitz Spec-R, rev210 mod, etc etc.

Currently have such a beefy actuator in there at the moment that it runs 18psi with the Blitz turned off.

.63's will drop about 2-3psi at redline. That's just the way it is. And you'll find similar sized turbo's from HKS etc will have very similar boost curves.

You've probably got a few psi to pick up, but i still think at the end of the day, you'll get up to around 14psi at redline and that will be normal.

Do the splitfires, see how it goes, and then sus things out a bit further.

Also, i really don't think running 14psi at redline, after peaking at 17psi is really such a bad thing if your engine isn't built :)

How's doing the work/tuning?

I've done all of the work, but trent has tuned it

You can still do it with internal gate by limiting the amount of exhaust pressure that you want to dispatch. Well nothing is impossible.

im not entirelty convinced by this stao, iv'e effectivly done what this device does because i have around 12mm of preload (eg shitloads) i dont think there is much extension in the rod left... any more preload (there is no thread left on the rod anyways) and it will probably wont open at all...

Just get trent to force the gate closed the do a careful run up. If its dropping immediately from 17psi then you'll have an easy cross over point, will rule out actuators etc.

If it drops regardless, it's the turbo. If it doesnt drop its something else :)

i'm looking for it to be running anything in the range of 17-19 psi... the boost quickly spikes to 17psi... but then drops immediatly to 12psi and holds there

This is interesting. So you effectively have a flatline 12psi boost curve? Not taking into account the 17psi spike?

2 problems.

You have too much gate preload. Gate preload adjusts the ramp of the boost, not neccessarily the peak boost. Too much and you get a nasty spike. Not enough and it builds boost too slowly.

What is the boost controller doing exactly? Is it wound all the way in? Does it give any adjustability? Theres no reason why it wont work.

If its wound all the way in and giving the 12psi then the signal line to the controller needs to be restricted.

Its simple boost setup really.

...and dont expect a flatline 17-19psi boost curve. Its still a small rear housing.

is that always 100percent true? if it drops regardless its the turbo?

is it possuble that there is a restriction still?

Well im assuming the exhaust has been dropped just to be certain :)

If not that can be done at the same time as everything... but immediate drop is suggesting otherwise as it wouldn't just "drop" harshly

Just noticed your said the boost dropped to 12 psi "immediately"

usually boost drops slowly as back pressure increases gradually. This "immediate" drop might be a EBC related thing.

Get Stao to bring one of his manual boost controllers and test it out.

my new splitfires arrived today , tomorrow after work i'll throw them in and see if that changes things, as the top end missfire has been getting worse... im sure the missfires wont help my boost issues

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • So I'll put filler past the repair area a bit to make sure I don't miss anything. Then I'll block it until it's almost level, put the guidecoat, then keep blocking until it's gone. Then it's still wavy.  In regards to hitting the panel, I saw this video might give more context - Skip to 0:47 he knocks it down. But yeah I'm sanding until the guidecoat is gone then checking because otherwise my filler is still well above the bodyline. Unless what you're saying is I should put guidecoat around it early, surrounding the filler then stip once it's gone?
    • I refreshed the OEM injectors with the kit and connected it up. It now ideals okay even with the IACV removed. Driving still has the same cutoff issue like the 550cc injectors so the issue is somewhere else. I bought FPG's Fuel Pump Hanger. I will be installing it next, but it is not as straightforward as I thought it was with my limited wiring knowledge and no instruction on the specific model I purchased (FPG-089). I also got the incorrect billet clamp as I could not find info on the OEM sizing.
    • Stop looking at the garage floor, and turn the radio up a bit louder if there's any strange noises...
    • No. Turbo shuffle and surge/flutter are not the same thing. Specifically, on a GTR, turbo shuffle has a definite meaning. On a GTR, the twin turbos are assumed to be the same thing and to operate the same way, exactly. In reality, they do not. Their exhaust sides are fed and exhaust a little differently, to each other. Their inlet sides are fed and exhausted a little differently, to each other. Consequently, when they are "working" they are often at slightly different points on the compressor map compared to each other. What this means, particularly when coming on boost, is that one of them will spool up and start producing extra flow compared to the other, which will put back pressure on that other compressor, which will push the operating point on that other compressor up (vertically). This will generally result in it bumping up against the surge line on the map, but even if it doesn't, it upsets the compressor and you get this surging shuffle back and forth between them That is "turbo shuffle" on a GTR. It is related to other flutter effects heard on other turbo systems, but it is a particular feature of the somewhat crappy outlet piping arrangement on RB26s. There are plenty of mods that have been attempted with varying levels of success. People have ground out and/or welded more material into the twin turbo pipe to try to prevent it. Extending the divider inside it works, removing material doesn't. There are aftermarket replacement twin turbo pipes available, and these exist pretty mush purely because of this shuffle problem.
    • You can temporarily* use lock collars to keep it in place until you can do the bushes, back the nuts off, slide them in, snug back up. *temporarily is often for ever
×
×
  • Create New...