I'm seeing more high flow pumps for the ol' IDI engine. But what about high flow injectors? The only thing I'm seeing id pop tested factory injectors and the garbage from DPS. Seems to me that the horsepower bottleneck is going to be the injectors.

Is anyone offering a high flow injectors? Is the injector now the bottleneck?

 

From my research, which is limited I admit, even the highest HP IDI is not burning all the fuel a high flow pump can provide. The precups can only hold so much fuel, anymore than that is a waste.

 

Racin will explain in detail im sure, but so far neither the pre-cup nor the injector is holding us back. Judging by dyno numbers this is affirmed as even the 150cc trucks still are right at 2.6-2.7 rwhp/cc. However to sate curiosities among other things, hes got 3 different sets of injectors he plans to dyno to see if and what the differences are.

IIRC, our injectors are moderately larger than CTD sticks, while they 1) have larger cylinders 2) flow more fuel and 3) can make more power with stock injectors than any pump that has been put on an IDI will match.

 

Ok, I have done some significant testing here, so I can report directly.

The biggest difference in being able to effectively deliver the amount of fuel even the biggest DB4 can put out, is pop pressure. Pop pressure decreases the injection duration so that more fuel can be injected in less time. There will be a limit to this at some point, but so far in my testing, I havent found it, and I have a good feeling its not within the realm of current IDI performance. I have Run dead stock pintle injectors on my 180cc pump, and I have run totally gutted pintle injectors on the same exact setup. I can tell you that the gutted pintles do tend to feel like they have a bit more umph (Faster injection? who knows, I dont know yet), but the drawback is a bit of raw fuel at idle, and when the pre-cups are cold, or cool off (long idle) I get a bit of idle haze. In comparison I didnt get that with the stock pintles. My next set of injectors will have stroked pintles instead of "lifted" pintles, so hopefully I can gain the best of both worlds depending on fuel flow... Of course, that is all dependent on whether or not anything makes a difference on the dyno. I plan on testing all three types at a 2100-2200 pop, and run them back to back on the dyno... If there is no difference, than we will know that stock injectors are sufficient for even the highest HP IDI's (DB pumps of course)...

The fact is though, the smallest part of the whole high pressure side of the injection pump is the injector Orifice... And the best way to open that up is to pull the pintle out of the way, whether that is by grinding, or "stroking"... Either way, with the orifice unobstructed, our injectors have the same nozzle area as 5x.022" cummins injectors, and if you wanna see how much HP those support, look it up... Now however, our pumps dont operate at nearly the same injection pressure, but my point is we are more than big enough for the amounts of fuel we are pushing.

I am still of the "opinion" that stock injectors will work for the amount of fuel a DB pump can put out, and there might be a small amount to be gained with "lifted" or "stroked" injectors, but there may be a give and take as far as burn cleanliness is concerned...

Im still working on the details, but this is the best intel I have at this point...