4bar map sensor, plx boost/vac electronic boost gauge. That's what I got.

I was reading 11.5psi with the gauges peak/hold feature. But my flashrpo is only reading about 8.5psi off the 4bar hondata map sensor....

my tuner tells me to trust my map sensor over the gauge.

If that's the case, I'm only making 8.5psi on a 3.4" pulley that is supposed to be 14psi (a bit lower at my elevation)

Any input appreciated.

 

The reason they don't match is because map sensors are calibrated at sea level and will always read lower than your boost gauge unless of coarse you live at sea level. I live at 4500 feet of elevation and the map sensors in all my boosted cars are consistently 2.5-2.7 psi lower than boost gauge readings. Atmospheric pressure changes as elevation changes. The further away from sea level you get, the further off the readings between the 2 will be. I personally go off what my boost gauge rather than my map just because I know this fact. My yellow car dyno'd 525whp at my elevation and my map read only 10lbs of boost while my boost gauge read 13psi. Given the charger wash a big gt40r but there is still no way my stock motor car on 10lbs would make that amount of power. It's funny too because a lot of guys that race around here will say they are running less boost than even their map sensor is reading just to try and make others think their car is so efficient and so much better because it makes X amount of power on such low boost. Makes me laugh.

Also boost pressures that a forced induction car runs will change with elevation as well. I've had cars in the past with a 1 bar spring only run say 10lbs when they should be at 14, but Im a turbo guy too so wastegate regulation compared to pulley size related to rpm is obviously different.

Sorry for getting off topic, hope this helps

 

The FlashPro reads absolute pressure. Your PLX sensor reads gauge pressure. At sea level, they should be the same. As elevation increases, the difference between the two will be equal to the difference between your atmospheric pressure and the atmospheric pressure at sea level.

The power your car makes is determined by the absolute pressure, not boost/gauge pressure.


Tim

 

Ok That makes sense. So seeing that my map sensor is reading 8-9psi. Is that right for a 3.4" pulley that's supposed to read 14psi?

 

Also..... My plx guage is an electronic with a built in map sensor. Wouldn't thst have been calibrated at sea level also?