Quote:
Originally posted by Tim Hancock
Zero, what risk of damage do you run by keeping the wastegate closed? This sounds interesting to me.
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there are LOTS of things that can go wrong if you do this cheap 'ricer-style' mod.
basically if you pinch off (or disconnect) the hose between the cycle valve and the wastegate, you can force the car to run maximum boost (determined by wastegate spring pressure).
sounds awesome, right? but wait! there's more! before you do this, you should know what the purpose of the cycle valve is, and why porsche engineers put it there.
the purpose of the cycle valve is to directly control the wastegate (thus, controlling boost). in case the cycle valve fails, the default 'safe mode' is to keep the wastegate OPEN (note: NOT closed). this will limit your boost to .2 bar (also called 'cripple mode' or 'failsafe mode'). there is a reason for this.
basically, the cv (cycle valve) is directly connected to the KLR computer and is the first and last 'insurance' the 951 has against serious engine damage from bad gas, engine knock, detonation, overboost, or the thousands of other things that could possibly go wrong. remove this, and you remove any sort of protection against serious engine damage. i've found that most 951 guys with destroyed engines have removed the cv and tried to bump boost up.
so to recap;
the pro: maximum power
the con: permanantly trashed engine
if you really want more power out of your car by upping boost, tune it the right way by using an electronic boost controller (apexi is popular). don't do it the ricer way by blindly upping boost with disregard to the consequences.