David Floyd

Will be going back to dyno shortly, with same 72lb injectors + resistors this time.

Good info here https://rennlist.com/forums/showthre...ight=injectors

https://rennlist.com/forums/showthre...last+resistors

Andy

I can't seem to find it now but I thought there was a tread a year or two ago where Chris Cervelli and even John said you didn't need resistors, now John is selling them with his injectors... ?

P.S. Did Chris Cervelli and Technodyne go out of business? He used to have some good write-ups on a website...

z3bra

Worst case, there's nothing lost by running resistors that are overspecced with regard to their wattage as long as the resistance value itself is what it needs to be. The only thing you're out is a little bit more money and they take up a little more space.

johne

Sounds good, thanks for the responses everyone. I just finished ordering a pair of 1.5ohm 50W resistors from newark.

Thanks again,
John

Lorenfb

The key that's being overlooked is the current dirive capacity of the DME injector
driver which is about 12 amps peak or about 3 amps per injector. So at 14 volts,
each injector must have a resistance greater than about 4.5 ohms. Note: Although
the DME has two injector pinouts, there's only one injector driver for the 2 pins.

As an example, if one must add 1 ohm per injector to achieve the above value of
less than about 3 amps per injector, this added resistor would dissipate about
9 watts (I sqrted X R). But since the worst case duty cycle for the injectors is
about 50%, the wattage can be 1/2 or a 5 watt resistor could be used. If just two
resistors are added, i.e. one for injector line, the power rating increases to
36 watts peak or about 18 watts RMS worst case, allowing a 25 watt resistor to
be used.

TonyG

You don't need resistors with the Siemens injectors.

I've run them on the stock DME for years on several cars with no problems.

TonyG