Why am I only seeing 6-7 PSI?

[JRfk7]

I have a '18 hatchback sport 6mt. I bought an UltraGauge OBD II reader to monitor boost. Under full tilt I only see about 6-7 PSI. Ultragauge says it calculates this figure by measuring manifold pressure and subtracting atmospheric pressure. I live at sea level. The question is: am I only seeing 6-7 PSI and not the 16.5 advertised because with more oxygen in the air at sea level, less boost is required to hit pre-programmed targets? Or am I missing something? Thank you!

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[PowerPerLiter]

I have a '18 hatchback sport 6mt. I bought an UltraGauge OBD II reader to monitor boost. Under full tilt I only see about 6-7 PSI. Ultragauge says it calculates this figure by measuring manifold pressure and subtracting atmospheric pressure. I live at sea level. The question is: am I only seeing 6-7 PSI and not the 16.5 advertised because with more oxygen in the air at sea level, less boost is required to hit pre-programmed targets? Or am I missing something? Thank you!

Your reading the actual boost pressure the engine is seeing which is after all the pressure losses within the system (intake intercooler various piping) this is a different measure than boost pressure at the turbo itself which is usually 3-4 psi different (higher) than MAP pressure within the intake manifold. Also you are correct about the elevation. These computers target a torque level not a specific boost pressure. Your car is making the desired programmed torque output with less boost than somebody at say 3000 ft. elevation (which they would need more boost pressure to meet desired torque command because of the less dense air)

 

[JRfk7]

Your reading the actual boost pressure the engine is seeing which is after all the pressure losses within the system (intake intercooler various piping) this is a different measure than boost pressure at the turbo itself which is usually 3-4 psi different (higher) than MAP pressure within the intake manifold. Also you are correct about the elevation. These computers target a torque level not a specific boost pressure. Your car is making the desired programmed torque output with less boost than somebody at say 3000 ft. elevation (which they would need more boost pressure to meet desired torque command because of the less dense air)

Thank you very much for your explanation! That is very helpful

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