Injector Spray Pattern

[mweiman]

Will you typically still be able to see the injector spray pattern on the top of the piston on a hpcr motor? I just tore down an 03 that had 2 top piston rings broke and the other top rings were very worn. Noticed there is no spray pattern from the injectors on top of the pistons. Is this normal, do they burn this clean? Or is it likely the injectors are not firing right?
Thanks,
Matt

 

[rbattelle]

Well, I would argue that any spray from the injectors would cause a pattern to show on the pistons, whether it's the correct pattern or not. But if none of the pistons show any spray pattern, what are the chances that all 6 injectors are equally bad but the engine still runs?

In other words, don't worry about it.

-Ryan

 

[sag2]

They should not look like this. The piston photos with the silver lines are actually flame cut lines in the piston from fuel contamination. You can also clearly see the spray pattern in the head, again from a "spray" not an atomized "plume". The bottom photo shows a more normal pattern, mostly just an outline of the 8 nozzle pattern on the piston.

 

[AH64ID]

My head is off and I can see the pattern, but not huge. I'll try to get some piston pics as they aren't going back in.

If the motor was burning oil then there is a chance the oil covered the pistons. It also is possible with stock timing that the flame front heat wasn't hot enough as it is with a tuner, in terms of crown heat.