Baseline fuel pressure for 24 LB injectors

[marshall_mosty]

For those of you with mustangs...

I've switched to GT-40X aluminum heads and 24 lb injectors. Since I previously had my fuel pressure set around 260/280 with 19lb'ers, I have no idea what to set the fuel pressure for my baseline testing. I plan on doing a "fine tune" on a dyno, but don't want to be way off in left field starting out.

I'm hoping for 290/305 with these heads... so if those of you with similar setups and power (David D., Jeff Brooks, for example) would kindly "share" your top secret information, I would appreciate it.

[BSharp]

It should be the about the same as 19 lb, 38-39 lbs.

[CMC17]

I agree that it should be the same. Fuel pressure will be the same and if the pump can sustain the volume, it shouldn't deviate from the 19lb pressure. The calibrated MAF (did you change the MAF?) for 24lb injectors will not have the same pulse width (less with 24lb) as a 19lb setup.

In my supercharged stang I ran 50lb injectors with a MAF calibrated for 30lb injectors. The Speedbrain compensated for the difference by adjusting the injector signal. Fuel pressure remained consant. FMU be damned!

[marshall_mosty]

Thanks for the info.

Yes, I changed the metering tube electronics to a unit calibrated for the 24-lb injectors.

[CMC17]

Thanks for the info.

Yes, I changed the metering tube electronics to a unit calibrated for the 24-lb injectors.

I figured you had.

Of course to be safe....dyno it with the A/F wideband installed just to make sure. I've seen some weird stuff between the MAF and EEC.

[gt40]

Back to your original question -- I run 24# injectors with a baseline fuel pressure (no vacuum,) of 38#. That's factory-spec, I believe.

[marshall_mosty]

Does anyone have the phone number to the Miata place at MSR-C that we use for our dyno inspections?

I need to re-dyno obviously and would like to have it shaken down on the dyno before hitting the track hard.