hi, i am kind of new, just bought a evo 8, car wasn't running at first, then lately got everything run, i tried couple times to full throttle the car, the boost gauge read about 15psi the max about 5000rpm, and then just stay there till 8000rpm, so is my car under boost.

and by the way, i know people say 18-19psi is the max boost for evo8, but i want to know do i read my boost gauge from 0, or from the vacuum reading where it idles.

thank you if anybody can help.

 

What boost gauge does your car have? Do you know if it has a manual boost controller?

 

I think that the zero on your boost gauge is equivalent to atmospheric pressure(14.7 PSI @ sea level). Any reading above zero would be positive boost pressure. Thus, 5 PSI indicates that your manifold pressure is 5 PSI above atmospheric pressure. Any point below the zero mark on the gauge would be a vacuum reading.

 

so here is the gauge that i took a picture it is from stri

is my engine hitting the max boost?

and is my vacuum reading ok?