Overboost Switch??

[AZ88Turbo]

Hi folks,

Following on from my ChargeCooler posts a while ago I am told that I have modified waste gate on my turbo and that is why I am pushing so much boost. The problem is now that I keep having the overboost switch cut in at around .75 bar. My question is (considering I just had the intercooler fitted): Should I change the waste gate to lower my boost or should I get an overboost switch with a higher rating, and if so how high and where from?

Any help will be much appreciated.

Thanks,

Mark
88 Turbo

[lotusguy]

AZ88Turbo said:

Hi folks, Following on from my ChargeCooler posts a while ago I am told that I have modified waste gate on my turbo and that is why I am pushing so much boost. The problem is now that I keep having the overboost switch cut in at around .75 bar. My question is (considering I just had the intercooler fitted): Should I change the waste gate to lower my boost or should I get an overboost switch with a higher rating, and if so how high and where from? Any help will be much appreciated. Thanks, Mark 88 Turbo

Mark,

Aha! The Plot thickens. I suspected that you had another reason, other than merely the installation of a chargecooler, to account for your increased boost. Your wastegate either is adjustable and was merely turned up (do you have a cap bolt extending underneath it from it's center?), or a non-adjustable wastegate which had the stock spring replaced with a stronger one.

Unless you're driving competitively, my advise is to dial down the boost and keep the overboost switch you have. The Esprit is plenty fast for most street drivers as is and running less boost will reduce stress on the engine and it's components and seals, especially the head gasket. Besides, you'll only be giving up bragging rights of one or two PSI at most. More is not always better.

Hopefully, you have the adjustable wastegate, in which case you could turn the adjusting bolt out (anti-clockwise) in ¼ turn increments, after releasing the locknut, until you get the proper boost reading on the gauge and no overboost condition.

Should you have the non-adjustable type, this will require removing the wastegate and bringing it to a Turbo or diesel shop so that they can replace the existing spring with a calibrated one of less pressure. Hope this helps. Happy Motoring! Jim'85TE



>> Edited by lotusguy on Wednesday 17th September 01:31

[AZ88Turbo]

Hey Jim,

I got so miffed at the cutting out last night I pinched the pipe to the overboost switch just for a test. It runs perfectly up to about .95 bar of boost in every gear and goes like stink. I think the turbo may have been messed with too as it seems to wind up very fast after it gets past the .5 bar mark. The plugs seem ok so it looks to be burning OK (not lean) so I am tempted to up the overboost switch to about 1.0 bar. It sure does feel nice to have that extra "zoom" and the car is a second car for me so I like to have all the fun I can when I'm driving it!

Does anyone have any idea where detenation would be likley to occour (how much boost) with the intercooler on the car? Just wondering how close I am and at exactly what level to put the overboost switch to be safe. Is there some sort of calculation?

The wastegate on the car is non-adjustable so it is almost easier to replace the overboost switch than it is to mess with the waste gate.

Can anybody reccomend a place to buy overboost switches? I see that aircraft suppliers seem to have them but they seem to be a higher setting than I need.

[mwmackenzie]

Hi

I have an uprated overboost switch that i no longer need as i've changed to a DTA ECU. If you would like to make me an offer on it feel free..

Cheers
Mark