I've been searching and have yet to find where my injector pluse width should be @ WOT. I just upgraded to 30lb injectors and an upgraded impeller for my supercharger. I seem to run between 11.11 and 12.9 @ WOT. 02 volatges have been between 800-900.

TY

 

That's a loaded question.

It *should* be between 8 and 10ms on a batch fire (16-20ms added together for each intake stroke), and it should mimic the torque curve overlayed on the BSFC, assuming the injectors are the proper size. BUT, you don't target a specific PW when you calibrate WOT, you target torque, which means A/F and timing. PW is just the product of the calibration.
IF you are just wondering if your injectors are big enough, and you want to do it (calculate duty cycle) after installing, and using empiracal data (PW vs RPM), that's ok. DC=on time/available time. DC=PW*(RPM/60000)*100% assuming batch PW in ms (half of total PW). Most people try to buy injectors to get about 85% max DC on a batch system. Max DC should happen at about the peak HP.

 

Thanks for the info! The main reason I was asking is that I have an FMU. I am running a 4/1 ratio because @ anything above 10 psi = 45 + fmu giving and extra 40psi = 85psi. I don't want to go above 100 psi and have the injectors go static. I though that the pulse width should be no more than 11.5. When I first put the 30's in, I burned a chip with the injector constant @ 30. Car pulled till 7psi, then fell on it's face. I droped the injector constant to 22 and the car pulled all the way to 11psi. Pig rich @ idle, but just trying to look @ my data logs to determine if I need to upgrade to 42's.

thanks again for the info!

As to find (PW vs RPM), that's ok. DC=on time/available time. DC=PW*(RPM/60000)*100% in my Craig moates software, what values am I needing to use. Injector base pulse width, battery voltage, map signal, rpm? I just want to get this right.

Thanks again

 

Doesn't your datalog show injector pulse width?

 

I have a base pulse width in ms.

So @ 3000 rpms with an injector pulse width of 14.43 look like this;

14.43 (300\60000) = .727 = ~ 73%?

12.1 ( 5000\60000) = %100...

 

Injectors vary alot about how they act at high operating pressures, some stay linear up to 130 PSI, and others get flakey, at really low operating pressures, assuming anything when trying to run more then 75 PSI can be risky unless you know for sure what you injectors are doing. Long term, I've heard nothing but greif about FMUs. The only really good one I know of never made it to market.

42s are tough to deal with, at the shorter pulse widths.

 

I'm currently running ford red top svo 30lb injectors. So the formula above. . . Is that how you fiugre out the % duty cycle and did I figure it correctly? Thanks for the info Grumpy, I figure I would need even larger injectors after the fact So, Bright Green Ford SVO 42's to come.

Thanks for the help!