Quote:
|
Originally Posted by BAN SUVS
There's no difference between absolute and relative "boost." If your gauge says 15 psi, presuming it's accurate, than your manifold is getting atmo+15 psi. I think what you're really asking is, does your MAP sensor read absolute (atmo+boost in bar) or relative (just boost). Everything I've read indicates you always want to read absolute, so I would expect the AP tune to be doing so.
|
Oh n0es, I sense a Dean vs. Kevin battle coming on... I'll swerve and see if I miss it....
OK, I wasn't thinking. Boost gauges are relative, that is why they have negative and positive numbers. there is no such thing as negative absolute pressure. Vacuum squared?
The feed from the AP/ECU is the same and matches the gauge wery well by the way. This also makes sense since the target boost range for the stage 2 maps is "15.8psi +/- 0.5psi", and this is the neighborhood I'm seeing despite being at altitude. So the boost map is likely based on relative pressure.
The MAP on the other hand is probably absolute as you said since I would bet that is what the fuel map is tied to.
If I only had a graphing calculator.... and the energy to go look up the equations, I could figure out what 15.8PSI at 4500feet vs. sea level is.
That lack of extra pressure is why I thought I could get away with the 93 octane map since most likely the primary difference is timing advance.
Anybody with a turbo and stock boost up here could probably run 89, or even 87 octane and not notice the difference. It might actually improve performance now that I think about it.
let the banter ensue...
