VR Racing injectors?
9 Second Club
Joined: Nov 2003
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From: Norn Iron
Low impedance use a peak & hold strategy.
ie, high initial current is drawn to open the injector quickly this then ramps down as less current is required to hold the injector open.
In years gone by this meant the injectors could open/close faster at the expense of requiring electrical circuitry to allow that high/low current control.
High impedance simply apply power and turn off power, no fancy control over current is needed and overall they draw a little less current.
With modern designs most good high Z injectors operate faster than the old low Z stuff now anyway so there really is no benefit in the low Z stuff other than them tending to be cheaper, or in cases where there simply arent big enough high Z injectors.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
As said, in years gone by there were few high flow high Z injectors. Partly because they would have operated too slow to be of any use at lower loads.
This just isnt the case anymore, and most highZ injectors will outperform lowZ of same flow sizes, except perhaps once beyond 2000cc or so.
But then there arent really any highZ options above that anyway so you need to use lowZ.
The crucial part is more down to how big you can go, without causing problems at the low end. So few n/a engines simply make so much power that you need really large injectors in the first place.
Whereas with boost it's a doddle to make loads of power and still need to have perfect road manners at the low end.
The other option, and even the OEM do it for lowZ is to run an inline resistor for each injector. This limits current flow through the injector and ecu driver so you can run lowZ injectors directly from an ecu that expects highZ
I can only imagine this must slow the injector down a little, but it's a fairly common practice and never really hard of it posing problems. Quite a few Toyotas, Hondas, Mitsi Evo's in the not too distant past etc run resistor packs so there must be some merit in it.
