F6

I need info on how far the injector pintle should be hanging, if at all, into the runner after welding the inj. bungs. I know they should be pointing toward the back of the valve. Should I place them just far enough into the air stream to make sure I'm not shrouding the spray pattern with the roof of the port or the injector bung.

Would anyone have info or pictures on how to do this the right way??

Arnold

F6

Very strange, no one seems to know how deep the inj. pintle should be hanging into the runner.

Injuneer

Not everyone uses pintle style injectors. How do you know if the spray pattern of the pintle style injector is compatible with the geometry of your intake manifold and head runners? Each type of injector has a unique spray pattern.

slowride94z

the pictures I have seen , the injectors were not protruding into the air stream ,but recessed a lot.
as for the angle the stock intake appears to be throwing its load on the outside wall of the runner????, instead of across the air stream

hogans are more vertical than stock, others are spraying almost perpendicular to the runner

I sir am no expert these are my observations and my questions

F6

I have also noticed that all converted carb manifolds or tunnel rams have the injector bungs welded vertical and not like stock on an angle. I have dozens of pictures of bung locations but only one actually showing the pintle from inside the runner. A friend of mine has his pintle hanging about 1/8" into the runner and then another friend having his 1/16" recessed.

Fred, I have used both pintle and disc injectors and haven't noticed any difference at all. It is true that there is more than one spray pattern, but how can anyone tell which is best, unless you dyno various bung/injector angles and various depth locations. Never seen anyone doing a time and money consuming test like this, and it seems that no one really cares about the results????
BTW, "Kenny Dutwiller did some extensive testing by moving them around but only found about 20Hp on a 2000+HP turbo charged SBC."

slowride94z

the blue tube is in the injector hole and almost snug, notice the clean or clear spot where the injector is spraying.
I guess they are angled toward the valves





hows this the lt1 stock intake has the injectors angled toward the back of the valve and tilted outward toward the head. I'm guessing shooting across the air stream isn't what the engineers were looking for.

the injectors are recessed

Injuneer

The photos of the various injector spray pattens I've seen are not all the same. The GM RP ball and seat (10* - 15*) has a very narrow spray pattern compared to the pintle style (15* - 30*). I would suspect that the RP geometry governed the placement of the LT1 injectors. Speaking many years ago with Pete Incaudo at CNC Cylinder heads in Florida, who had input to the LT4 head/intake development, he was adamant about not touching the area immediately below the injector boss when porting the LT4 intakes to match his LT4 head ports. He seemed to feel the issue was critical, and any change in that area could damage injector geometry and adversely affect power.

I doubt many people can afford or justify heavy investment in injector location and spray pattern analysis. But it doesn't mean its unimportant. My tuner, who's on the same very limited list of MoTeC authorized general performance tuners as Ken Duttweiler has strong opinions regarding the application, location, and spray timing of various injectors. But selection was often preferentially affected by factors other than spray pattern, e.g. adaptability to higher pressures to produce shorter pulse widths and allow the injection cycle to better match the intake valve opening cycle.

F6

slowride94z, nice pictures you have there.
Yes, the stock injectors are angled towards the plenum and therefor spraying at the back of the valves. Since the converted intakes have their injectors set vertical, they should be spraying right across the air stream and not towards the back of the valves. Placing the injectors vertical has maybe something to do with lack of room because the plenums are wider than the LTx plenums.

Fred, I'm using Ford SVO 36# F7PU-A4A and since I will be spraying across the air stream just as all others as it seems, the 15°-30° pattern would be better suited than the GM RP injectors.

slowride94z

F6

Again, great pictures!!!
I will try to take the same pictures for documentation purposes before I'm ready for installation.

Injuneer

You can just see the end of the injector in this LT4 cut away view:

F6

Picture is a little small, but I get the idea.