MAP reading vs Boost

[TheHydro]

Hey guys. I have a Whipple with a 3.625 pulley and I am running a 3.5 bar map sensor reading off the intake manifold and displayed through my ngauge with the zeitronix zt-2. At full boost I’m seeing 9psi from the map sensor and according to my tuner I’m at 11 pounds of boost which sounds right for the pulley size. I know manifold absolute pressure is different that boost because of the atmospheric pressure but I am curious if my reading of 9lbs from the map sensor at full boost is accurate?

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[EFI]

How are you getting that 9psi level of boost?

Is it based on an arbitrary calculation that the ngauge displays, or is it an actual calculation of kPa pressure in the manifold?

At the same time, how is your tuner calculating his 11psi level of boost?

 

[Tommy V]

My buddy logs boost with a map sensor wired into his sct,also has a regular boost guage and also has a boost reading on his boost controller.All three read different pressures,so it really depends on where the signal is coming from and the device used.

 

[stang17]

With 3.625 pulley, catless Kook headers, and 132 mm TB we made 12-13psi.

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