Ive been fighting with some really bad fuel economy, trying to track it down and fix it. No luck so far though.
Ive got a set of DDP 75hp injectors on the truck and im starting to wonder if theyre involved in the economy issues somehow.
From what I gather the 12v in the dodge uses 145* injectors and a smaller bowl and the marine uses 155* and a larger bowl. The DDPs I -think- use a 155* injector, maybe a 370 marine as their starting point. But they also come with .6mm sealing washers which place the nozzle deeper into the bowl.
My timing is at 15 degrees, previously it was at 19. No real change in economy so maybe Im barking up the wrong tree here.
Anyone tried 7 hole injectors like the cpp's and got a benefit to fuel economy?
Or maybe raised pop-off pressure (and advanced timing to compensate)?
When i tested my DDPs the pop offs were around 3300-3500 psi if I remember right.

 

How bad is the fuel economy you are speaking? You have an aftermarket cam which should benefit mpg with more air, but I don't know if the change in injectors is going to gain much at this point.

I haven't really noticed any mileage changes other than fuel quality from summer to winter. Speed and start/stops are the other factors that affect my per tank usage.

 

AFAIK, its the 90 and 140 DDP's that are 155, the lower stages are still 145 degree. That being said, I'd try any injector that you know has been working well, just for diagnosis purposes. Might look into something like SDX 5x12 VCO's, should be comparable to the 75's you're running now.

All the aftermarket injectors I've run and seen for the 12v use the thinner seal washer.

 

Im looking at three sources for injectors. I might try a custom set with higher pop pressure and more smaller holes to see if that helps atomization.
Anyone know what the stock pop-off pressure is supposed to be? Looks like 4500psi unless that spec was from the VP. I think mine tested at 3500 or so. Wonder if thats related to the economy issue?
Lot of variables, just in the injectors! Wonder if Ill ever get to the bottom of this problem.

 

260 Bar/3800 psi. A lot of performance injectors will go to 280-290 Bar.

 

hmm, I thought it was 4500psi which is about 310bar. dunno where I got that number from.
Id like to set it on the high side for atomization. Maybe advance the timing to make up for the extra time building pressure.
Truck is running like total crap right now =(