How high can you go?

[jasoncitrano]

How much boost do you guys think you can safely run on a evo III with stock internals and 680's i'm at 20psi right now, also how can you tell how much higher you can raise the boost with race gas?
can you run race gas and raise boost a little at a time and watch the knock to see how high you can go without getting to much knock? or what?

 

[herostar]

Every car is different, you're just going to have to tune it as much as you can until your timing and knock go bad. On race gas on a properly set up car I'd say maybe 25-26.

 

[Sean485]

Depends on condition of engine, type of IC, how good you can tune, octane of fuel, ambient temp, what other kids of mods you have (cams, smim, nitrous, etc). Start conservitivly and watch things with the logger, and remember too that more boost doesn't always mean more power.

 

[billdo_83]

Invest in a pocketlogger so you can see what your engine is doing.

Then you can start to bump up the boost and make adjustments to your car.

 

[jasoncitrano]

i have a pocketlogger...just need to know what i'm looking for, like what kind of problems i would see when i start to run to much boost.

 

[saw wave analog]

knock and timing retard. get an egt and a/f gauge too if you want even more security, fuel pressure is good as well

 

[billdo_83]

you start to get excessive amounts of knock and also timing starts to dwindle.

I try to run less than 7 counts of knock but i shoot for 0 counts of knock across the board.

 

[jasoncitrano]

i have a ETG, datalogger, a/f gauge, safc II, and blue wire mod done. right now when i show knock on my afc, it says 0%, but when i go to actually see knock it's up around 23 or something like that? how do you read it? i was told that 23 or so was so small of a percentage that it wasn't going to show up on the afc yet is this correct?

 

[billdo_83]

knock and timing retard. get an egt and a/f gauge too if you want even more security, fuel pressure is good as well

A/F gauges are useless dont go by it.

Just go by the knock count that is on your PL not on your S-AFCII

23 is too high
after 7 counts of knock the ECU starts to retard the timing of your car.
Read up the basics of tuning. It sounds like you need to learn the basic laws of tuning.


Read some of this
http://www.roadraceengineering.com/newafc.htm

and this

http://www.pocketlogger.com/forum/viewtopic.php?t=143

 

[Quasimondo]

Raise your boost until it knocks.

Back your boost off until it stops knocking.

That's your limit.

 

[jasoncitrano]

awesome, thats what i wanted to know thanks...also how accurate is the safcII at displaying the knock sensor values?

 

[saw wave analog]

A/F gauges are useless dont go by it.

this seems to be the common sentiment in dsm land, and for the most part they are useless for precision tuning purposes, i will always run one though because its just one more way of knowing that something is wrong. vague or not, if it shoots down to .85 volts you know you are about to blow something up so you get out of the throttle.

a bright, bargraph or single led style one like dawes device makes *is* indeed a quite useful indicator

 

[billdo_83]

Mine told me that my o2 sensor was dead but that was about the only time that it has ever been useful for me.

 

[steve]

how accurate is the safcII at displaying the knock sensor values?

Not at all. There is no relationship between that an SAFC shows and what the ECU sees.

Steve