9secz

I built this setup to measure the minimum pulsewidth for various injectors. By minimum pulsewidth I mean the shortest pulsewidth that results in enough fuel flowing through the injector for an engine to idle.

http://para.noid.org/~lj/InjectorPulseTest.jpg

I've only looked at three part numbers so far, all made by Siemens-Deka, and all tested at 43 psi fuel pressure. Here's what I found:
60 lb/hr high impedance: 1.5 ms (this injector has a "Mototron" part number in ink)
72 lb/hr low impedance: 0.8 ms
83 lb/hr low impedance: 0.9 ms

As expected, the high impedance injector had a fairly broad transition from no flow at all to a reasonable stream, whereas the low impedance injectors had a sharper cutoff. I'm convinced that is why guys have a hard time getting the big high impedance injectors to work well at low loads.

RedHardSupra

iTrader: (1)

sweet setup! thanks for sharing the data. are you able to do more testing for other popular sizes, like svo 30/42s?

9secz

Anything you want to send me! I have Delphi 65, 75, 85, and 95s plus Bosch 160s in stock that I'll be testing over the next week or so.

RedHardSupra

iTrader: (1)

ah damn, should've told me last week, i just put mine in. a friend of mine has an extra spare, i'll ask him.

WS6FirebirdTA00

iTrader: (33)

ahhhhhhhh i should have sent u mine out, i am having troubles low load getting my racetronix 38's to idle, i threw the cam in to try and make it need more fuel. but if i get to low levels of fuel needed the car has a hard tiem running. awesome man!!

slow

iTrader: (7)

nice work.

Your values for 60's are very close to some I have for those injectors as well.

I don't know why people have trouble making them work, I use them for fords all the time with no real issues, but I have full batt comp tables as well.

Ryan

GrannySShifting

iTrader: (10)

Yes this is why for years guys go to a low Z injector with big pound hour stuff. Factory cars (german stuff etc) have been running lowZ stuff form the facotry even for years

CHarris

iTrader: (5)

I've got the Motron 60's running well at 1.8-1.9 ms on my combo listed in my sig...

9secz

I truly don't mean this as any kind of slam: A piece of research I'd really like to see is for someone who has big high-z injectors working well to switch to low-z injectors. Maybe the Motrons really work as well as low-z 60s would, or maybe you would notice a real performance difference if you switched.

BTW, CHarris, do your injectors say Mototron on the body? Or Motron?