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posted on May 13th, 2013 at 07:02 PM
Over boost protection
Hi
My son drifts an old Skyline. His ECU has no boost pressure sensing like later ECUs. Last year he torched 3 pistons after the Turbosmart wastegate
line melted and the motor went into uncontrolled boost.
What we did may be useful to turbo VW engines particularly the ones running carbs.
I was thinking of a way to have a overboost safety switch. I bought an adjustable pressure switch on eBay and then had Leigh Harris set it to 18 psi
on a test bench and then I fitted it to a spare hole in the inlet manifold, it was then wired into his Bee*R revlimter using the 2nd rev limiter set
to 1000 rpm.
This weekend he ran the car in Matsuri at Wakefield Park, he took me out for a few passenger runs and then the car developed a miss, a check of the
eboost showed that boost had spiked to 18.9 psi, it normally runs around 14 psi.
The boost cut we had wired in had just saved a motor and been the only thing stopping him from ending up the same as last year but on the Saturday.
What caused it you ask? Well we were pretty confused as well. Re plumbed the wastegate so it was just getting a signal from the intake manifold, no
change. I ripped the line back off and blew into the wastegate and pressure was going straight through.
I took the wastegate cap off and sure enough, the diaphragm was not seated correctly. The diaphragm looked brand new and after giving it a good once
over, we threw it back in and the mystery leak was gone. No idea what caused it but Turbosmart nearly cost him another motor!
