Drive pressure and head gaskets.

[RonA]

A while back I installed a gauge to check drive pressure. I found that while it was ok up to around 50 psi of boost(55psi drive), above that it went up quickly. At 60psi of boost, drive was in the 75 to 80psi range. I have since switched secondary chargers and my drive pressure at 60psi boost has gone to 55 psi. Am I less likely to blow a head gasket at say 65/65(boost/drive) than 60/75? Or does the drive pressure not really matter as far as the gasket is concerned?

 

[Piers]

Ron,

Although drive pressures are important, egt's will kill a head gasket faster than drive pressures. There are lots of guys running the poor little HX35/12 at 40+ lbs boost... which equals 70+ lbs of drive pressure.

 

[lmills]

Piers, I know this has probably been beat around before , but is that with an external wastegate to bypass the 12 housing? Or is that with using the wastegate that is built into the turbine housing?

 

[Piers]

That was with a stock HX35/12 turbo, in a single charger configuration.

 

[lmills]

Oh I gotcha.