Angle of the Dangle - Injector Aiming

[Fuelie Fan]

I'd tend to agree for the most part. But, if you think about it, DIRECTLY at the other side might not be so bad, as the fuel might just bounce back into the airstream. Imagine washing your car: You're not dumb enough to point the hose directly at the body, becuase you know you're gonna get soaked. But, as you change the angle, gradually less is reflected. In the port, you WANT the fuel off the surface of the runner. You really want to avoid just coating the walls of the port. Would I do it that way? Probably not.



If you can get the spray to the valve, the OE trend is usually to run a very narrow (they're called "pencil") spray pattern injector. The problem with these are, if your aim is off, then you will hit the port at a shallow angle and have horrible mixing. OR, if your injector timing is off, you'll be firing a highly concentrated (not easy to evaporate) spray right into the combustion chamber, basically getting no pre-mixing at all. So, most aftermarket guys prefer medium spray cone angles of around 20-30 degrees and pointed "in the general direction" of the valve. This way, their aim doesn't have to be exact and they get pretty good mixing regardless of valve timing because the cone doesn't impact the wall for a pretty long time, allowing some mixing with the air charge to occur first. And, when it does hit the wall, it doesn't have to far before it reaches the hot valve. Without the R&D necessary to perfect the aiming, that's what I would do, and it sounds like that's what TWM did. If you plan running at 7000+ rpm, you might want to read the other post I made concering Larry's setup and consider moving your injectors further upstream in the port.