Jump to content
SAU Community

Stock Turbo Overboosting with No Bleeder...

strutto

By strutto,
in Engines & Forced Induction

 Share

Recommended Posts

BHDave Grand Master

BHDave

Posted
Posted

If it's not dropping back it sounds a bit like wastegate creep as you have improved the efficiency of the system. I had this problem once i installed a full exhaust on a series 4 13bt but they are notorious for creep.

The car should make a small amont of boost late in the rev range with the gate wired open but not that much!

For a long shot: does the car definately have a stock turbo on it? It hasn't been swaped for an rb20 one maybe?

strutto Grand Master

strutto

Posted
  • Author
Posted
Sounds like oil in the actuator, I've seen it happen to a R33 recently. Boost will keep rising under accelleration intil you back off. This was using avc-r and it wasent that solinoid because we swaped it into another and it worked fine.

It's got nothing to do with the actuator...

If its wired open it shouldnt make any boost at all. :uh-huh:

Well it does... Thanks anyway...

If it's not dropping back it sounds a bit like wastegate creep as you have improved the efficiency of the system. I had this problem once i installed a full exhaust on a series 4 13bt but they are notorious for creep.

The car should make a small amont of boost late in the rev range with the gate wired open but not that much!

For a long shot: does the car definately have a stock turbo on it? It hasn't been swaped for an rb20 one maybe?

Yeah hopefully dropping the exhaust after the front pipe might reveal something... It seems like an efficiency problem to me but why am I the only one experiencing it?

Car has a 3" dump and front in one... (not split wastegate)... 3" Trust cat back... Fairly old cat back though... 3 mufflers in it too... All straight through but... Hmmm wonder if I'm up for a new exhaust...

I expected a little boost up high with the gate wired open, but it's making heaps...

Car was stock as can be when I bought it... First owner in Australia... So I doubt the turbo is different... Looks like a 33 unit to me... No signs of any work being carried out around there in the past either...

:mad:

Weq Contributor

Weq

Posted
Posted
It's got nothing to do with the actuator...

 

   

 Well it does...  Thanks anyway...

 

 

Yeah hopefully dropping the exhaust after the front pipe might reveal something...  It seems like an efficiency problem to me but why am I the only one experiencing it?

 

Car has a 3" dump and front in one...  (not split wastegate)...  3" Trust cat back...  Fairly old cat back though... 3 mufflers in it too...  All straight through but...  Hmmm wonder if I'm up for a new exhaust...

 

I expected a little boost up high with the gate wired open, but it's making heaps...

 

Car was stock as can be when I bought it...  First owner in Australia...  So I doubt the turbo is different...  Looks like a 33 unit to me...  No signs of any work being carried out around there in the past either...

 

:)

if u wired the gate open and its still making boost. something must be up with ur wastegate flapper or there is a blockage on the diversion port. its the only explanantion as to why the ehxuast gasses arnt bypassing the turbine.

Pandaemonaeon Enthusiast

Pandaemonaeon

Posted
Posted

I noticed the same problem when I got my exhaust fixed. It's a full 3.5" setup and the front pipe had a big dent in it. When I took this dent out and removed the cat on stock boost it was maxing at about 0.8 bar. On saturday it was real cold and was maxing at about 0.9 bar, so the car had bugger all power from 5000rpm upwards as it was hitting the boost cut.

RBVS Community Regular

RBVS

Posted
Posted

ok we can all stop talking about the controling system , he has said more than once that he had the waste gate wired fully open. This is not that un common after fit ment of a larger exhaust system. the turbo becomes more efficient (free flowing) increasing boost in the top end. ways to combat this is to..

modify the dump in a way to incrase the flow of the waste gate gas, at the moment it simply cant divert enough pressure from going though the turbo wheel to get your desired boost level.

If that has been done or is done to the best you can the next step is a bit more hard core but i have done it and got resaults and so have others that i told. (may fined on a search)

this is to drop the exhaust of the back of the turbo to acess the gate.

you will see that the the gate over laps the waste hole buy about 3 to 4mm.

with a die grinder or round file would be safer increase the diameter of the hole buy 1 to 2 mm but make shore the gate will still easly cover the hole. also pay attention to the angle the hole is in relation to exhaust flow.(90 degrees) taking a bit of the inside edge out will make it flow better also. 1mm in diameter will make a big differance.

See the thing is the system all works well in the stock set up but once you change one thing it has an effect on another so you have to even the ratio back.

Doctor Mentor

Doctor

Posted
Posted

Instead of wiring the wastegate open, you should be able to slide the wastegate control arm of the flap, so that the wastegate flap can be left......flapping.

This way you will definately know that the wastegate is 100% open when on boost instead of trusting your wiring job.

You should not be making any boost if this is done correctly.

Have you checked to see if the wastegate arm has not be bent? May have been suggested before?

I dont think you really need to go the the extent of what RBVS is suggesting as its not a common problem you are experiencing.

My money is on the wastegate arm being bent.

The shitty thing is its probably something really simple. Thats cars for you...

strutto Grand Master

strutto

Posted
  • Author
Posted

OK, from the top...

Probally a long shot but that DIY boost controller you had before did you have to put a restrictor in the actuator line?

The restriction was adjustable (ball valve) and has definately been removed... Good idea thought... :cheers:

ok we can all stop talking about the controling system , he has said more than once that he had the waste gate wired fully open. This is not that un common after fit ment of a larger exhaust system. the turbo becomes more efficient (free flowing) increasing boost in the top end. ways to combat this is to..

  modify the dump in a way to incrase the flow of the waste gate gas, at the moment it simply cant divert enough pressure from going though the turbo wheel to get your desired boost level.

  If that has been done or is done to the best you can the next step is a bit more hard core but i have done it and got resaults and so have others that i told. (may fined on a search)

  this is to drop the exhaust of the back of the turbo to acess the gate.

  you will see that the the gate over laps the waste hole buy about 3 to 4mm.

  with a die grinder or round file would be safer increase the diameter of the hole buy 1 to 2 mm but make shore the gate will still easly cover the hole. also pay attention to the angle the hole is in relation to exhaust flow.(90 degrees) taking a bit of the inside edge out will make it flow better also. 1mm in diameter will make a big differance.

  See the thing is the system all works well in the stock set up but once you change one thing it has an effect on another so you have to even the ratio back.

Firstly, you are correct... This has nothing to do with the controling system... The front half of the exhaust is about as good as it's going to get ATM... I still haven't had a chance to drop the cat back and take it for a spin to see how that goes... I understand what your saying about the wastegate outlet and I've heard of this being done before... But as Doctor says below, it's not a common problem... I'm honestly not confident enough myself to go filing / grinding away at the exhaust housing of my turbo... If it comes to that, I'll send it to GCG and they can "go to town" on it...

Instead of wiring the wastegate open, you should be able to slide the wastegate control arm of the flap, so that the wastegate flap can be left......flapping.

  This way you will definately know that the wastegate is 100% open when on boost instead of trusting your wiring job.

  You should not be making any boost if this is done correctly.

 

  Have you checked to see if the wastegate arm has not be bent? May have been suggested before?

 

  I dont think you really need to go the the extent of what RBVS is suggesting as its not a common problem you are experiencing.

 

  My money is on the wastegate arm being bent.

 

  The shitty thing is its probably something really simple. Thats cars for you...

Doctor, when I wired the gate open, I did remove the actuator arm from the gate flap... The flap was, as you say, flapping... I then wired the flap open so there was no chance of it flapping closed when I was testing it... I hope you understand what I'm saying... There was no tension / preload on the wastegate flap at all... It was 100% open for 100% of the time I tested it...

With this setup, it still made excessive boost...

So I don't think it's the control arm as this was disconnected...

As you say though, it's probably something really simple... I just can't for the life of me work it out... :D

Thanks all...

RBVS Community Regular

RBVS

Posted
Posted

i interpreted it as the waste gate being disconected and instead of flapping around its just sucured in the fully open position buy some wire. If thats right and in doing that its running 12psi plus how could it be a bent aculator rod, all the controling of boost is eliminated form the situation and it just leaves us with the way the gass exits.(flow)

as iv said i have had hands on with this situation. Ive had my waste gate flapping and made 14psi at 7000rpm. So i did what i sudjested above and boost droped to 10psi.

also done with a mates car. ill try and fined the other thread were someone ealse also has done it.

like i said it is a bit hard core but i can only offer my advise. most times just fixed with a proven dump pipe like a hks twin which offers better flow for the waste gate than a stock dump conected to a 3'' system.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Duncan
      Mistakes were made, my R34 Story

      By Duncan · Posted

      Have a look at that (shitty) pic I posted. You can see AN -4 braided line coming to a -4 to 1/8 BSPT adapter, into a 1/8 BSPT T piece. The Haltech pressure sender is screwed into the long arm of the sender and factory sender (pre your pic) into the T side. You can also see the cable tie holding the whole contraption in place. Is it better than mounting the sender direct to your engine fitting......yes because it removes that vibration as the engine revs out 50 times every lap and that factory sender is pretty big. Is it necessary for you......well I've got no idea, I just don't like something important failing twice so over-engineer it to the moon!
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      Yup. You can get creative and make a sort of "bracket" with cable ties. Put 2 around the sender with a third passing underneath them strapped down against the sender. Then that third one is able to be passed through some hole at right angles to the orientation of the sender. Or some variation on the theme. Yes.... ummm, with caveats? I mean, the sender is BSP and you would likely have AN stuff on the hose, so yes, there would be the adapter you mention. But the block end will either be 1/8 NPT if that thread is still OK in there, or you can drill and tap it out to 1/4 BSP or NPT and use appropriate adapter there. As it stands, your mention of 1/8 BSPT male seems... wrong for the 1/8 NPT female it has to go into. The hose will be better, because even with the bush, the mass of the sender will be "hanging" off a hard threaded connection and will add some stress/strain to that. It might fail in the future. The hose eliminates almost all such risk - but adds in several more threaded connections to leak from! It really should be tapered, but it looks very long in that photo with no taper visible. If you have it in hand you should be able to see if it tapered or not. There technically is no possibility of a mechanical seal with a parallel male in a parallel female, so it is hard to believe that it is parallel male, but weirder things have happened. Maybe it's meant to seat on some surface when screwed in on the original installation? Anyway, at that thread size, parallel in parallel, with tape and goop, will seal just fine.
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      How do you propose I cable tie this: To something securely? Is it really just a case of finding a couple of holes and ziptying it there so it never goes flying or starts dangling around, more or less? Then run a 1/8 BSP Female to [hose adapter of choice?/AN?] and then the opposing fitting at the bush-into-oil-block end? being the hose-into-realistically likely a 1/8 BSPT male) Is this going to provide any real benefit over using a stainless/steel 1/4 to 1/8 BSPT reducing bush? I am making the assumption the OEM sender is BSPT not BSPP/BSP
    • funkymonkey
      Jacks that fit under GTR lips that can reach the subframe?

      By funkymonkey · Posted

      I fashioned a ramp out of a couple of pieces of 140x35 lumber, to get the bumper up slightly, and then one of these is what I use
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      I wouldn't worry about dissimilar metal corrosion, should you just buy/make a steel replacement. There will be thread tape and sealant compound between the metals. The few little spots where they touch each other will be deep inside the joint, unable to get wet. And the alloy block is much much larger than a small steel fitting, so there is plenty of "sacrificial" capacity there. Any bush you put in there will be dissimilar anyway. Either steel or brass. Maybe stainless. All of them are different to the other parts in the chain. But what I said above still applies.
×
×
  • Create New...