Had an interesting discussion today in class about readings I was getting from my boost gauge. Now before today I always assumed that when my boost gauge said 26psi it meant 26psi considering I was measuring directly from the intake manifold. My teacher brought up an interesting point (he's a performance course teacher), he said that the turbo will create back pressure causing the back pressure to go back into the cylinders and then into the Intake manifold causing false boost readings. He claimed the only way to read true boost would be to have a gauge reading back pressure then to subtract that number from manifold pressure and thats your true boost readings. Does this sound right to you turbo guys?

P.S. i was boosting 26psi on my mitsu race engine not the del sol

 

26 is alot

 

what kinda turbo are you running on the dsm???

 

maybe i'm missing something here but that doesn't make too much sense to me.

 

Pressure is pressure. If the gauge reads 26 psi, then you have 26 psi at your intake manifold.

 

yeah but your missing the point, it's reading pressure but it's reading boost pressure and back pressure that has gotten into the intake manifold. The more i think about it the more it makes sense. Yes, it will read 26psi but in actuallity it would be somewhere around 22psi with 4psi worth of backpressure.

It's an evoIII b16g turbo.

 

thats what i want to know.

 

yes it matters if you want to know how much boost is at the intake manifold generated by the turbos compressor side alone, but as the pressure that goes into the cylinders is what's at the manifold if you get 26psi then you get 26psi. so it's not like the pressure gauge is overstating what is going into the engine itself.

 

yeah i know what you mean, but what he's saying is that not all of that "26psi" is actual intercooled turbocharged air, and that the exhaust backpressure which is not even worth burning is casuing to show false boost readings.

 

evo III big 16g, it's capable of up to 35psi if cooled and if ya have enough hp behind it!