Damian in NJ

I was told that the exhaust should be here within the next week or so. I'm having the driveway sealed next week, so the car will stay in the garage. If I can get the exhaust delivered then installed I'll try to have the dyno pull done the week of August 30th. I won't have separate pulls done with/without the Cargraphic cat, too much time, labor, and dyno money to do so.

Phil Harrison

>> I wonder how much can be gained just by increasing the fuel part of the ratio.

Apart from wide open throttle, the DME controls the fuel to give stoichiometric (14.7:1) by using the oxygen sensor feedback. If you used a higher fuel pressure then the injectors would just be given a shorter opening time (pulsewidth.)

Chip calibrations should be done with no feedback loop (oxygen sensor disconnected.) When connected afterwards the oxy sensor corrects the basic map.

Damian in NJ

Phil, is the 14.7 the desired number across the board, or does that change with revs, wide open throttle, etc? I've been hearing 13:1 or so are a target number with wide open throttle.

Phil Harrison

14.7 is for part throttle/idle. Wide open throttle 13:1 is right i.e. running rich so combustion temperatures are lower & avoiding pre-ignition (detonation/pinking)

Damian in NJ

Thanks, Phil, I'm certaintly running leaner than that at both WOT and part throttle.