Okay, I am running the Holley commander 950 pro version on my little turbo 4cyl with a 3bar map sensor. I am wanting to run 27-28# of boost but the map sensor and boost gauge are giving me different readings.
From what I have gathered this chart should be pretty close?


correct?

Well in testing I would go out and make a tuning run and see the autometer gauge swing past 30, but when I get back and check the data logs it shows the map reading never going above 275 Both the sensor and gauge are on the same line and before the intercooler.

So I got out a pressure regulator and hooked the feed line to my compressor.
First thing I noticed is when just sitting key on/engine off the map reading is 94, and with it maxed out it is 294

With a
gauge reading 30psi the map is putting out 287
gauge reading 25psi the map is putting out 254
gauge reading 21psi the map is putting out 229

And to get the map to read it max of 294 the gauge is pegged about an 3/16" past 30psi.

I have also checked the boost gauge against a few other gauges and it seems to be correct.

Am I just missing something here? I thought the 3 bar read up to 30psi not over? The way it looks the top row of my fuel and timing tables is not ever used.

Also I am around 600ft above sea level.

Any input would be greatly appreciated

Thanks
Randy

 

294 kpa is 28psi
287 kpa is 27psi

Generally, most gauges are a few psi overly optimistic. I'd be more inclined to believe the map sensor.