I did a full throttle run with my scanmaster the other day. I got an injector pulse at 11.0 on the scanmaster. Anybody know what percentage this works out to be regarding the duty cycle of my injectors? I currently have 24lb svo injectors. Thanks in advance.

 

with that kinda power i say you are really close to maxing them out if they arent.

 

I've seen a pulse width in the high 14 range so you still have a way to go

 

Duty cycle is your pulse width, divided by the time available in two crank revolutions, so you need to know an RPM along with the pulse width to determine if the injector is being max'd out (greater than 90% duty cycle).

At 6,000RPM the time available in two crank revs is 20mS. So if you see an 18mS pulse width at 6,000RPM, your duty cycle is:

18 / 20 = 0.90 = 90%.

An 11mS pulse width doesn't even come close to maxing things out unless you are seeing it at 7,500RPM.

As a guideline, maximum possible pulse width vs. RPM:

5,000rpm - 24.0mS (80%DC = 19.2mS)
5,500rpm - 21.8mS (80%DC = 17,5mS)
6,000rpm - 20.0mS (80%DC = 16.0mS)
6,500rpm - 18.4mS (80%DC = 14.7mS)
7,000rpm - 17.1mS (80%DC = 13.7mS)
7,500rpm - 16.0mS (80%DC = 12.8mS)

 

man, my 30lbs SVOs must be way overkill for me then with the 224/230 and stock heads... thanks for the guideline Fred!

 

Thanks Injuneer. Strange, I got that reading at about 6000 rpm. Maybe I should check it out again, something doesn't sound right. Thanks. Do you race at englishtown Injuneer? I don't think I've seen you there.

 

I thought SVOs were rated differently than stock injectors? If so then if what I'm thinking is correct then you swapped to smaller injectors since the stockers are 24#s themselves... No?

 

Ford rates their injectors at 35 psi. when installed on an lt1, with stock fuel pressure 43.5, they end up putting out a bit more. About 26 or so.

 

I checked my duty cycle again. I still got an 11.5 on my scanmaster for the left bank at 6000 rpm. This doesn't make any sense, that means I'm only getting a 58% duty cycle at 6000 rpm? Something isn't right, anybody have any thoughts? Thanks in advance.

 

Just a thought, but did you ever get a tune for those bigger injectors?

 

Yep, Bryan did the tune. I only gained 1 pound of torque over the hypertech, which are the numbers I have in the sig. I got the last injector reading with his program.