borg230rover
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| posted on 18/9/12 at 08:09 PM |
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Turbo boost pressures
Im after a bit of help with R1 Turbo
I have a 7.5psi actuator set to standard has not had the spring pretentioned at all.
I have a boost pressure gauge plumbed into the inlet manifold.
My problem is this at WOT and full boost my pressure gauge is reading around the 12psi mark, there is clearly something wrong there and I cant put my
finger on it. I have an intercooler so you would expect the pressure at the inlet manifold to be slightly less the the actuator set pressure ie:
7.5psi at actuator should see something in the region of 5/6psi at the inlet why am I seeing 12psi ish at the inlet?
I few things to note are,
The gauge I am using is a very expensive not cheap and cheerful from ebay so it should be pretty good.
I have done a complete leak test on all the pipework.
The boost reference line from turbo to actuator is new and has good seal at both ends no leaks.
I have a bit of a therory about this myself but not sure how it stands in reality, could my turbo be producing more pressure than my engine can
physically use? Surely the waste gate would deal with that?
Will a dump valve achieve anything?
Is the pressure everywhere in the turbo system ie, Turbo, pipework, intercooler, plenum, throttle bodies, inlet the same pressure I get the small
pressure drop after the intercool, however for example will the pressure at the turbo be the same as the pressure at the plenum whilst boosting up?
Just remember "There is always going to be someone quicker than you"
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RAYLEE29
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| posted on 18/9/12 at 08:24 PM |
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You could try testing the actuator and finding out what pressure it takes to move the wastegate
also check that the actuator is seeing full boost pressure and doesn't have any kind of bleed off
What boost pressure do you want
Is the wastegate free to move ? It's not seized is it?
Ray
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matt_gsxr
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| posted on 18/9/12 at 08:34 PM |
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It will be turbo dependent, but in some cases the wastegate outlet on internal wastgates can be restrictive.
On the car installs many wastegates have active controllers which probably help mitigate this.
If you google "wastegate porting" you will see what I mean. I'd guess that your exhaust is less restrictive than anything the
factory made.
Just a thought.
Matt
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Norfolkluegojnr
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| posted on 18/9/12 at 09:29 PM |
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Sounds like a bad actuator to me.
Was it new? Could be a tired spring? Or not the Actuator you thought? Is it adjustable
Or fixed?
What turbo are you using?
Edit: is the wastegate opening fully and correctly? Did
You modify the actuator/wastegate at all?
[Edited on 18/9/12 by Norfolkluegojnr]
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borg230rover
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| posted on 19/9/12 at 06:45 AM |
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I am going to test the actuator today just to confirm how much pressure it is taking and to make sure it is opening freely.
Someone has posted that my exhaust could be very unrestricted, I guess what they are saying is that it had a very good follow allowing tr exhausted
fumes to travel out faster, spinning the turbo up more.
Just remember "There is always going to be someone quicker than you"
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Norfolkluegojnr
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| posted on 19/9/12 at 08:00 AM |
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Start with the actuator and see where it takes you.
On my Mini I run a T2 with a straight through exhaust to a cherry bomb - virtually nothing to restrict the gas flow and haven't had any issues
like this.
I assume there isn't a bleed valve fitted? check you aren't losing pressure around that if there is.
the hose from the turbo to actuator - are there any T pieces coming off it?
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borg230rover
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| posted on 19/9/12 at 08:14 AM |
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No T pieces at all it is straight through pipe from turbo to actuator, I have set it up like that until I find the reason for it doing this then I
will probably fit a boost valve. A point to note is that when I first set the turbo up I had the gauge coming off of a T piece from the hose we are
talking about going to the gauge and it showed 7.5 psi which is correct, its only now I am taking pressure from manifold inlet that I am having this
problem.
Just remember "There is always going to be someone quicker than you"
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Norfolkluegojnr
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| posted on 19/9/12 at 08:19 AM |
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My boost gauge runs from the manifold - its the most accurate place, so you are correct to have it there. (incidently this is also the line
you'd use to trigger the dump valve should you choose to use one)
Sounds like either the actuator isn't firing at the right pressure, or the waste gate is restricted somehow.
when you check the actuator, check that its opening the wastegate fully. Test it is connected, then disconnect the actuator and see if the waste gate
is opening to the same point (fully).
Seems odd your pressure was correct before though. Have you changed anything else in that time?
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borg230rover
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| posted on 19/9/12 at 11:17 AM |
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I have tested the waste gate with my compressor this morning, set the continuous air flow to 7.5psi and it appeared to be spot on, opened and closed
perfect. The only thing that now springs to mind is I have recently put on a new turbo gasket, it was one of these gaskets that you cut out and make
youtself I wonder if this has caused the waste gate to not open properly as I did cut it a bit rough.
Just remember "There is always going to be someone quicker than you"
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Norfolkluegojnr
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| posted on 19/9/12 at 11:47 AM |
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Would have thought it'd blow past that without issue.
If the actuator is opening at 7.5psi, and the wastegate is clear, its a bit odd.
is the boost gauge correct? if you get 7.5psi at actuator, but 12psi at manifold, it must be something to do with the waste gate not passing the gases
quick enough.
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CNHSS1
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| posted on 19/9/12 at 06:07 PM |
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when hooking up the actuator rod to the wastegate penny arm, how much pretension is required to get the hole in the rod to drop over the lever? 1/2 a
hole is the norm. If you need to pull the actuator rod further to drop onto the actauator arm, thsi could account for the engine seeing 12psi.
couple of other things, where are you taking the boost signal from? the compressor housing of the turbo (most common) or the inlet manifold? often the
manifold is more reliable in my experience as its what the engines actually seeing.
wheres your boost gauge plumbed into?
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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