bigger injectors and a piggy back computer? How is it that the ZPI kit can run 5-6psi without bigger injectors and a piggyback? Is it all in tricking the maf by maf tube sizing, cause even with the ecu seeing more air from the maf it will still only give so much fuel based on the fact that the computer thinks it n/a and not giving enough fuel to run 11-12:1 air/fuel which is in the safe range.

 

Our Stage 0 Kit runs 10.x:1 Air Fuels at 6.5 psi on the stock injectors.

The car is smart enough to deliver the correct fueling, both by MAF voltage and the fact that it has a factory wideband style o2 sensor.

 

but the car should be trying for a 13:1 AF ratio... how did you trick it into shooting for 10.5:1?? is it just the MAF tube sizing?

 

the real question should be how does ignition timing get adjusted? its been proven that the A/F ratio changes, as the MAF sees more air and the ecu compensates for more air. the maf sees more air via turbo than it ever would via NA, but somehow the factory ecu keeps adding more fuel, almost like Toyota engineered the car for boost from the factory due to the S/cer....YET it has also been shown that timing does not change at all. So instead of running say 23 degrees of timing at 6psi, the car runs the factory 28 degrees or whatever it is.

this is also proven from the ZPI dyno test that showed thier s/c'd car making 20-30lbs more torque than most reflashed SC'd cars. as timing is relative to torque numbers.

 

yeah, more timing equals more torque=more hp.

I didn't know that the more air the maf sees the richer it runs, that is flippin awesome. I only want to run about 4psi for a little bit until I buy fuel managment so I think ~4psi with a rich af/r and the stock timing shouldn't be to bad.
Ive heard that ZPI doesn't run the stock size maf tube. is that true?

 

too much timing = detonation when it comes turbo cars with hot charge temps as well........ timing isn't always the answer, but then agian for 6psi it really doesn't matter.

 

yeah; but, with only 4-5psi and a nice FMIC I don't think it would be that much of a problem. the effective compression ratio with 4psi is about 11.7:1

 

Fuel and timing table in the Scion adjust off one another. Where on a typical engine a ECU would not pull timing until the knock sensor would pick up detonation while this is usually to late especially on new low emission cars. The Scion ECU actually adjusts timing off A/F. We can lean the car out without and timing control and watch the ECU on a scan tool lean itself out. While this is only a safe margin within reason this does provide an additional safety window over that of a typical setup.

Please do not take this the wrong way as the boost increases and the margin of reasonable error reduces this is not an acceptable way to tune the car. But on 6PSI this is more the acceptable, there are stage 0 cars with 45k on them that prove the longevity is there also.

 

Hows that solara 2az kit working out? Is the computer basically the same?

 

Gota give it to zpi for doing all the testing and stuff on this instead of just assuming something like that is safe.

 

They already have a donor car and the kit is on the car...Im just wondering about some fuel/air results. Zpi is working on a stage 1 for the car last I heard

 

The solara project is coming along nicely the ECU is not as smart as the tC and it will require a piggyback ECU even at low boost levels....well at this time anyway. We are limited at the stage 0 type kit until we finish with the ESK development as the car we have here to do R&D on is a auto.

 

so....
If I were to use a stock sized maf tube and run about 4psi, when the MAF reads all the extra amount of air being sucked in it will give enough fuel to be safe at ~4-6psi?