Hey guys my vl is havin problems holding boost its hittin 16psi but drops down to 12psi as it revs. The Motor has a t3/4 highflow, tx2 crow cam, ported head and has been bored 40thou. I have tried a few bleed taps and at the moment i have a profec B elect boost controller but nothing seems to hold boost. Any idea what to look at next?
Picture 020.jpg (http://www.calaisturbo.com.au/attachment.php?attachmentid=18200&d=1186916985)
Selective leak in wastegate diaphragm perhaps ?
ie. Takes initial surge ok then as the diaphragm swells out to push
actuator it leaks air, suggest test it with a compressor which has a good
regulator on it so you dont damage the diaphragm, actually its very easy to
damage them with a compressor...
Curious how quickly the boost drops and does it coincide with a change
in wheel spin or is this on a dyno and fully repeatable ?
yeh mikes right sounds like a waste gate problem or even accuator.
Does it feel as it has more turbo lag??
n with a e-boost controller u should be able to dial out any problem like that by letting less pressure reach the accuator as revs increase... thats in the case of say 2 psi drop
What size exhaust housing/wheel? has the exhaust wheel been cutback at all?
Maybe with the hi flow comopressor and the cam/headwork you are getting a big pressure build up in the exhaust housing that stalls the exhaust wheel.
Also what size exhaust?
Mike,
The workshop that tuned it couldn't get it to hold boost on the dyno and it doenst really mater what gear your in or anythink it is always the same adn it spikes to 16 then drops stright down to 12. I hooked up a extension spring to the waste gate lever to prove the accuator wasnt blowing open or something silly like that and it still coundnt hold boost.
Hyped6,
The exhaust housing it standard and it is a 3 inch exhaust turbo back.
mmm, How long is the spike, fraction of a second or a second or so ?
Have you maybe got an inlet manifold leak, check the torque on the
inlet manifold bolts that going into head.
Did you see the AFR drop after the spike when on the dyno ?
For all intents and purposes it does seem to act as if the wastegate is "set"
for 12psi, many inlet parts could well leak selectively at higher pressure,
what about the comp cover bolts, faulty PCV valve (bit of a stretch), any
rubber pipe, etc anywhere between outlet of compressor and manifold - anywhere in there could be a crack or even a loose hose clamp yet might
not feel that loose - so check em all,
