low z vs high z

[81 elky]

Can anyone explain the difference in low impedence vs high impedence injectors and what corresponding ecm mods are required to this newbie? Please write slowly so I'll understand...

[PaCemkr86]

FUEL INJECTORS*

High Impedance:
42.5# Delphi/Holley (009)
50# Delphi/MSD/Holley
57# Siemans(Deka)
60# Mototron



Low Impedance (ECM mod required):
55# Siemans(Deka)
65# Delphi/MSD/Holley
72# Siemans(Deka)
75# Delphi/MSD/Holley
83# Siemans(Deka)
85# Delphi/MSD/Holley
95# Delphi/MSD/Holley
160# Bosch


nice thread on injectors here

http://www.t6p.com/forums/showthread.php?t=16562&page=2

[kenmosher]

High Impedence and Low Impedence refers to the resistance of the electromagnetic coil in the injector.

Low Z = 2 - 4 ohms
High Z = 12 - 15 ohms

A Low Z injector is designed to be fired with a "Peak and Hold" driver ... i.e. a very brief high current pulse "yanks" the injector open and then it's held open by a lower steady current. This requires a VERY beefy injector driver and a injector coil capable of high current.

A High Z injector is by far the most common type and is designed to be fired with a "Saturated" driver. The driver sends a constant current to the injector to open and hold the pintle/disc. These drivers use a lot less current and typically the injectors are cheaper since they don't need a high current coil.

The "hybrid" injectors, such as the Mototron 60-65# injectors use a coil that can be driven by EITHER peak & hold or saturated drivers. This allows them to be used by either an OEM style ECU or an aftermarket/racing ECU.

[81 elky]

Thanks Ken, that was the answert I was looking for. I was looking at the 60#ers when I noticed 'high impedence injectore, no ecm mods required' and I wondered what it was all about.

[turbo87]

i see the new high z injectors at full throttle speed are long does this mean you have to mod your fuel rail for them to work?? I would like to get them and not have to use a chip or mod the ecm any one know????

[kenmosher]

No, they are "long" (i.e. standard size).

There's a "short" version for applications that use a much shorter form factor ... the short injector is about 47mm tall.

The "long" ones are 74.50mm tall (pretty much standard size)

[turbo87]

thank you for the fast responce i will order my set right now was worried about it when it said long .One more upgrade done thank you again

[Ts86ttype]

You mentioned that you didn't want to use a chip or mod the ecm. No mod on the ecm but you will need a chip [prom] to run the larger injectors with your system.