Engine/Transmission (1998.5 - 2002) Never asked before injector questions?

[BDaugherty]

I'm seriously considering buying these 80HP injectors from City Diesel.

Jammer Injectors (Complete) City Diesel - Diesel Performance

They add Edge Jammer nozzles to your injector bodies. Then flow and pop test them. My question is not the age old "whose injector should I use?"

I have a 2001 HO engine with Edge Juice W/Attitude. I feel like I already have as much timing advance as I want. I also know that any set of aftermarket injectors will be set to the SO engine's popoff pressure, thereby giving me more timing advance. I'm trying to decide between having professionally flow and pop tested injectors that will give me a little timing advance versus installing my own nozzles which, in my mind, would keep the popoff pressure closer to stock but maybe not be as precision. Any thoughts or comments would be appreciated.

 

[ThrottleJockey]

Timing in a VP-44 injection pump is controlled electronically through a signal from the ECM to the motherboard on the pump itself. The injectors have little to do with it, if at all. The term 'pop off' is more associated with the P-7100 pump which deals in pressures around 17000 psi. The VP-44, which everybody had high hopes for with it's electronically controlled timing, deals in pressures around 14000 psi, less pressure, but more control. Or so they thought.



I know that an SO truck responds better to a fueling box (a longer fuel delivery curve) and that the HO truck just LOVES an injector change to a couple of sizes larger (more fuel pressure in the same timing curve)



The stock SO injector is actually bigger than a stock HO injector. My '01 HO really woke up after an injector upgrade to Jammer 2s. The Banks Ottomind fueling box... ... ehhh, not so much.

 

[BDaugherty]

I'm glad to hear that you had good results with stage 2 injectors.

I also understand what you're saying about the timing. However, timing advance at the pump plus injection delay equals total timing. What I'm thinking about is trying to keep total timing down since the box I'm running has no timing control.

VP44 injectors are not very different from P7100 injectors. They have a spring loaded needle and seat. When the fuel delivery pressure exceeds spring pressure, the needle lifts off the seat and fuel is injected. I don't know the exact figures, but it is my understanding that SO injectors "pop" at a lower pressure than HO injectors. Replacing HO injectors with aftermarket injectors set to SO pop pressures will have an effect on total timing. How much, I don't really know. It may be negligable, but I'm still curious.

 

[BDaugherty]

So I installed the 80 hp injectors today. It wasn't too bad a job. Truck fired right up after install, idled rough for less than a minute, and then smoothed out. With my Juice set on stock, I could tell a big difference in power. With the Juice turned up, it was easy to get the EGTs up high. Bottom end power increase was not what I had expected, but midrange and top end definately picked up. Bottom line is that the power increase was different from what I expected, but not bad for $340 and a couple hours work. I've been keeping a fuel log for the last couple months and I'll report back with any difference in mileage.