Hi all,

Our cars measure boost both pre and post throttle and this can be logged by an Accessport under Pre-Throttle boost and Manifold Absolute Pressure.

It looks like the in-dash boost gauge reads Pre-throttle pressure.

My questions is when people mention that they're running xxx psi/bar of boost, are people talking about MAP or pre-throttle?

At full load / WOT I see a delta of 3-4psi between the two..and while cruising at constant rpm (no load) I'll see ~0psi pre-throttle and about 8psi of vacuum at the MAP sensor.

Just one of those things that I was always unsure about and would love to know.

Thanks!!

 

Hey bud,
MAP has some simulation/calculation behind it. Think of Pre-Throttle as more of a real-time/analog boost reference.

 

Afaik only 997.2 have an actual pressure sensor post throttle ... The 997.1's use some sort of algorithm to calculate MAP ...

To answer your question, it really depends on the setup standard vs VTG, with standards you need a boost controller and those run off the MAP ....

 

Awesome..thanks gents!