I am getting ready to install a new XST04S into my rebuilt streetported motor. I have a Nip high flow pump and SX regulator. I have been reading past posts about injectors and can not decide what to use. I will be using at PFC to control. Can I use 1300's or do I need 1600's with a resistor? What size resistor do I need and which side do I put it on? What fuel pressure do I need to run. Thanks in advance for any help.

Note: I want to tune for 1 bar.

Thanks
Chris

 

Chris,
I tried using some overbored injectors at 1300, and was getting about 85% duty cycles at only 11.5-12 PSI. I didn't want to push things, so I went with the 1600s + resistors.

I am running about 40 PSI of pressure at 0 manifold pressure. This is about what the stock system runs. So at idle you have vacuum, so it drops the pressure down to about 31-32 or so.

Resistors go on the "+" side of the injector. I believe that on our cars, it's black with yellow stripe or something like that. I used one 10 Ohm, 20 Watt resistor on each new secondary injector. Since 10 Ohm, 20 Watt is hard to find, they are actually four 10 O, 10 W connected together in a diamond shape to make what I wanted. Lots of other people say that 10 O, 10 W just by itself is fine and use that.

Brian

 

Are you saying that you used 4 - 10O, 10w per side or 2 - 10ohm, 10w per injector. Just curious was that something Dave recommended?

Thanks
chris

 

I used 4 x 10 Ohm, 10 Watt per injector.

Each set of 4 is wired into a diamond shape so you end up with this:
____^v^v^____^v^v^____
INJECTOR-----< >------Wiring Harness
\___^v^v^____^v^v^____/

This gives an overall effect of 10 Ohm, 20 Watt.

I believe that Dave actually uses 3 Ohm, ?? Watt. I don't know for certain, so don't take it too seriously.

The way I arrived at my setup was I just calculated the difference in resistance from stock 850s to low impedance 1600s. It is about 10 Ohm. Then for the wattage, I just used V = IR and P=IV to find the value I wanted. I think that with 20 Watts I'm pretty damn safe.

I think that most people just use 10 watts.. so maybe that's OK too.

 

Damn that picture looks like ***. I am no ASCII artist!

Brian

 

Here's how I did em....