[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Safe boost

Lets keep assuming you want to do this yourself and not pay me or someone
else lots of money to do it for you.

If you do the mod I suggested then the overboost limit is gone! Should the
wastegate diaphragm split or something else happen to cause extremely high
boost, your engine will not cut. However I assume you are aware enough to
know when you have another 5000HP and will back off immediately. The car can
then still be driven on a very light throttle until the diaphragm is
replaced. I have never experienced the diaphragms splitting and have only
heard of 1 or 2. As was evidenced by the number of replacements which were
ordered via this list (about 7 I think) this is a very rare thing. However,
it can happen and you must make the decision as to whether you want to take
the chance on being no 8 or not.

The divider resistor is a more risky option in my opinion, simply because
you are advancing the ignition and can cause detonation. The way it works is
that the pressure sensor will give out upto 7v maximum but the computer can
only read upto 5v. So if you divide the output from the sensor to make the
computers input 5v when the sensors output is 7v, you still have the boost
limit in there but it has been raised by about 4psi. Therefore if you have
15 PSI boost you will have the ignition timing for 11 PSI which is too far
advanced and can cause detonation. Light detonation will not be heard and it
can cause damage and if left long enough, will cause head gasket failure,
piston melting and head damage. As you might guess I don't recommend this mod.

The last option was the resistor divider together with a remapped timing
curve to put the timing back where it was. This is the best option of the
three, but the work has not been completed yet. It will require a
reprogrammed chip and 2 resistors plus the goodwill of RDH and his
willingness to give the info he has worked on away, and accept
responsibility for it. We have not had a time frame yet. If its coming soon,
its worth waiting for.

I hope that clarifies the situation.

Peter Wales