More boost less timing, less boost more timing???

[22shelby]

so kinda been pondering this and wanted to here what the community has to say about it... i know most of you would say just ditch the little mitsu for a garrett, which i have one, but im kinda in a spot where i'm liking this whole pushing the bone stock set up... now we all know add most boost you get more power, add more timing get more power, add more boost and timing and potential kaboom!! i'm curious to hear what yall think as far as upping the boost and just keep backing of timing... or would it be a bit more benificial to back the boost down and add in some more timing... my set up right now is just a stock 2.5L better flowing air filter, high flow 2.5" exhaust and 3 bar cal...

now with the timing table i have set up right now, i can push about 17 psi on 93 octane w/o and knock detected, i push any more boost and the cel lights on me... sometime i can hear it but i really dont push it... i've punished this 2.5L enough... now say at this point would it be beneficial to keep pulling timing to get the knock under control or would backing off the boost and bumping the timing up give me more of the "seat of the pant" jollies???

now please i ask of you not to fill this post with "oh you should ad an inter cooler or you should spray water alky"... i know this... i have them... i can put them on anytime... i just want to see what i can do on the stock off the factory 1989 components... the best case scenario would be a day at the track where i can lap it as much as i can but dont really have that opportunity, but i do have wide open 2 lane back country roads at my disposal (close course of course )


so what yall think??

[BadAssPerformance]

Power out of a Mitsu? ShelGame is da man!

[ShelGame]

Mitsu specific question or Generic?

Generic answer is, add boost until more boost won't add power. Eventually, you'll get to the point where more boost (for a given turbo) only adds heat and pressure, but not more mass air flow. Once you get there, you play with timing in order to maximize power.

I think you'll never make as much power at 15psi (for example) and playing with timing as you will at 18psi.

In my experience, that 'max boost' point on the Mitsu is 19-20 psi. It will make higher boost than that, but it stops making power about there. Above that, the air just gets hotter; you don't really flow more air. Of course, that point is completely different for the T2 Garret or S60, etc. turbos.

[22shelby]

yeah pretty much a mitsu specific question, Rob your "examples" were the exact numbers i was thinking... so taking those numbers the added 3 psi would out weigh the extra timing that would be able to be run on the lower boost... whats seems to be wierd to me is that at part throttle at the high boost level its a clean consistant acceleration, but rollin to it till WOT it will knock, whats weird to me is I have the part throttle timing table and the full throttle tables matched.. I'm assuming it is doing this because of the extra load from the PT to the FT...