Originally posted by Josch:
This Evo I worked on only had 17psi boost from the factory (tested with Autometer boost gauge). So I cranked it up to 19psi. Some of the boys on the Lancer forum are running 26psi with stock long blocks. Seems a bit high for a full time street car though.


A little high!

Talk about well out of the efficiency range.

They are just pushing hotter air rather than more air.

I'd be happy to post Mitsu's compressor maps for you to lick Josch! Butt I digress...

Mitsu turbo's are designed and rated to run at 15psi (peak efficiency)

Anything past 19-20psi is just pushing hot air. Nothing more! So you actually did pick a good level to set it at.


Also boost level is a reading of the restrictiveness of the entire setup (intake, heads, chamber, exhaust etc)
It is not an tell-tale indication of MORE power.

This is a major reason why intake & exhaust mods generate such high increases on boosted vehicles. You just made the "setup" more efficient so therefore the subsequent "boost" pressure would drop. (not cfm flow mind you, just less restriction) However since the boost pressure is "preset" at a specific level via the wastegate actuator it's also like raising the boost too! Therefore it's really 2 increases in one. Not just the gains from adding one specific part.

2000 SVT #674 13.47 @ 102 - All Motor! It was not broke; Yet I fixed it anyway.