MSefi.com read only forum (Jan.15,2018)

hi all,

after months of breakdowns and convincing, ive finally convinced my old man to convert his 1973 triumpth 2000 to fuel injection, and also to get some control of that horrid points ignition, but i know what to do there...

i am making an intake manifold from a stock carb unit, a twin stromberg unit, by simply fitting a plenum and throttle body from one of my hondas to it...

which brings us to my question, injector selection:

was looking to use 6x 180cc 2.5 ohm honda injectors i have lying around (connected parallel) and use a 12 ohm resistor in series with these, does anyone know how many watts this resostor will need to be? i know megasquirt will see this as a single 12.4 ohm injector but am unsure of the current draw...

alternativley, the other plan was to mount two large injectors (around 550cc) inside the plenum, facing the collectors of the intake,as the carburettors did...a resistor for these two would be smaller in terms of wattage...but it still dont have a way to work it out!

if anyone can help, it would be greatly appreciated!


mike

1973 triumpth 2000
ms1 v2.2
msextra 029y3

If you are using one 12 ohm resistor per bank (don't put all six on one resistor), assume a worst case of a 14 volt drop across a 12 volt resistor. Use P=VI=V^2/R to get a power rating of 16.3 watts. As resistors run VERY hot at their rated power, I'd upsize them to 50 watts.

thanks matt, much appreciated!
will probably look at 2 resistors (3 per bank) as it will half the strain that would be on a single one...

hope you are well!


mike

I'm using the original injectors on my Rover SD1 without the original series resistors - they are also 2.5 ohms but four per bank. The V3 board is specifically designed to drive low impedance injectors directly. If you do wish to use resistors the Jaguar XJ6 Series 111 has them in a single pack. It's normal to use one per injector.