Ok I know over 35 psi in an hx35 is like playing Russian roulette. But I hear people using it for twins an being just fine no one complains on that, what's the difference? Still overspooling isn't it?

 

The bigger charger is seeing the higher boost numbers in a compound setup.

 

The high pressure turbo is just repressurizing what the atmospheric charger has brought in.

 

The important thing is pressure ratio not the pressure the turbo is putting out. 35psi at sea level is about a 3.4 pressure ratio. (boost pressure+Atmosphere pressure/atmosphere pressure=Pressure Ratio)

In a twin turbo set each turbo is considered a stage of compression. The low pressure turbo will compress the air from atmospheric pressure to 20lbs or so(pulling numbers out of the air here) That is a 2.3 Pressure ratio. If the High pressure turbo compresses that to 40lbs it would only be a 2 pressure ratio. The overall boost pressure is greater but the pressure ratio the turbo sees is much lower.

Pressure ratio is the ratio of boost pressure from after the turbo to before the turbo expressed in atmospheric psi.

 

my hx35 has been pushing 45 to 48lbs of bost for over a year now

 

What are you egts at? At 45-48