overboost...
05 August 2002, 12:14 PM
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...well, it aint clutch slip this time 
Found out big time about overboost at the weekend.
Looked at the boost gauge, and it was zapping past 1.0, when I floor it, which it never did before, hit's about 1.1 then WHAM total lack of boost (fuel cut I suppose) and a 'hit the windscreen' moment, car backs off, and if I keep the peadal down it boosts back up and then does the same thing.
Am guessing this is true overboost?
Must be due to new clutch, so old one must have been totally fecked, because it's never got over 1.0, always jumped up to it, then fell to 0.8 or lower.
still goes quick, just means I can't floor it, due to hitting the windscreen. So I have to be a bit more gentle with the right foot,. which is prob a good thing.
Soooooo. What can be done to get rid of this? different restrictor? boost controller (hmm, up the boost a little
fun! )
comments please people
A nice quick and cheap fix would be good!
Found out big time about overboost at the weekend.
Looked at the boost gauge, and it was zapping past 1.0, when I floor it, which it never did before, hit's about 1.1 then WHAM total lack of boost (fuel cut I suppose) and a 'hit the windscreen' moment, car backs off, and if I keep the peadal down it boosts back up and then does the same thing.
Am guessing this is true overboost?
Must be due to new clutch, so old one must have been totally fecked, because it's never got over 1.0, always jumped up to it, then fell to 0.8 or lower.
still goes quick, just means I can't floor it, due to hitting the windscreen. So I have to be a bit more gentle with the right foot,. which is prob a good thing.
Soooooo. What can be done to get rid of this? different restrictor? boost controller (hmm, up the boost a little
fun! )comments please people
A nice quick and cheap fix would be good!
05 August 2002, 02:36 PM
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Hi Markus,
check where your restrictor(s) is, if it's close to the solenoid it will cause more overboost and surging than if you fit it close to the turbo itself. Put the restrictor into the other end of the pipe right up against the turbo outlet pipe.
The position of the restrictor will significantly affect the way the car boosts, the further away from the solenoid (towards the turbo) the better the control.
If you use one in the turbo to solenoid line and balance that with one in the vent pipe then you can play with the sizing to achieve virtually no overboost.
The FCD will lift the cut which will allow you to run more boost but you should fix the overboost problem first.
check where your restrictor(s) is, if it's close to the solenoid it will cause more overboost and surging than if you fit it close to the turbo itself. Put the restrictor into the other end of the pipe right up against the turbo outlet pipe.
The position of the restrictor will significantly affect the way the car boosts, the further away from the solenoid (towards the turbo) the better the control.
If you use one in the turbo to solenoid line and balance that with one in the vent pipe then you can play with the sizing to achieve virtually no overboost.
The FCD will lift the cut which will allow you to run more boost but you should fix the overboost problem first.
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25 August 2002 11:17 PM