I realize there are so many variables it would be hard to quantify the neccessary ones for each individual engines tuning needs. I am curious as to what the accepted tuning values are for finding the correct angles. Would it be at the highest piston velocity/port velocity in relation to injector size and injector duty cycle percentage? Is the idea to keep fuel from pooling in the intake the least amount possible and using the valve temperature and air velocity homoginize the mixture? This idea seems to lend itself to favoring larger injectors. What is the crossover point when using smaller or larger injectors based on duty cycle? Can phase angle be accurately figured without going into transient fuel?I'm sure cam profile and distance from the injector to the valve, among others, also play a large role.

Sean

 

Sean,

There are two things to realize about injector phase angle.

1. The time available for injection decreases with engine speed. Take a quite reasonable injection time of say 5msec, and figure out the number of crankshaft degrees that time takes at various engine speeds. When you see the results, with a typical port injector, do you think you could actually inject the fuel at a specific enough time to have to worry about piston motion and camshaft timing?

2. Everyone injects on a closed valve anyway.

-Rob

 

The angle of injection does change my idle characteristics. I guess it all ends up in the same place, so to speak.