Two quick questions:
1) What's the difference between high impedance and low impedance fuel injector; and which category does a Ford SVO fall into?

2) On a 94 F-body, is the NGK TR5 or NGK TR6 the stock plug? Which one is colder for nitrous usage?

 

not sure on the injectors...

but tr55s are stock....6s are the colder ones

 

A high impedance injector has a coil winding resistance of 12-15ohms. With a 12V power spply, it pulls about 1 amp. Takes a very simple "driver" connected to the PCM. Typically used for injectors up to 40-50#/HR.

Beyond that, the injectors get so large that they slow down, and are difficult to "turn down" to the low pulse widths required for idle. Low impedance injectors have a much lower coil resistance.... 1.5-3.5ohms, and are designed to accept a very high inrush current (peak) to open the injector quickly, then see a reduced current (hold) to keep the injector open. This requires a more sophisticated "peak and hold" injector driver.

The stock PCM's are generally designed to drive only high impedance injectors. But it is possible to get an external "black box" converter that allows the stock PCM to drive the low impedance injectors.

Stock type and Ford/FMS/SVO/Bosch/Denso pintle style injectors are generally available in sizes to 42#/HR in high impedance. Beyond that you can find a few larger high impedance injectors, but as size goes up, they will predominantly be low impedance.

 

Thanks I appreciate the response.

From what I understand, SVO's are hard to come by; not made anymore. Is this true? Who is the actual manufacturer of Ford's SVO injector? -Ford?!

Daniel

 

they are now called ford racing, not SVO, and probably made by Bosch