Diesel Place banner

1 - 4 of 4 Posts

·
Registered
Joined
·
238 Posts
Discussion Starter #1
Just thinking out loud. Has anyone ever looked at the duty cycle of the injectors themselves when they are running? Is there any chance that the duty cycle (on time vs off time) when running a programmer or tuner is pushing the injectors to the limit of the acceptable duty cycles? Could very well be accelerating wear and tear. I know that there are some here that say even at 500+ HP that the fuel system has not reached it's limits, but how can you tell if you don't have a way to datalog what some of the compenent functions and limits are?


Jess
 

·
Registered
Joined
·
448 Posts
Jess,


Good point, but wouldn't exceeding the injector duty cycle cause electrical failures in the injectors and not mechanical ones?
 

·
Registered
Joined
·
7,187 Posts
a64pilot said:
Jess,


Good point, but wouldn't exceeding the injector duty cycle cause electrical failures in the injectors and not mechanical ones?

I do not know for sure but for each engine revolution each cylinder gets a certain amount of fuel based on TPS and other variables. The fuel is applied based on a pulse width not how far an injector opens. It stays on or open for longer timje for more fuel.


I do not see a problem other than not enough flow thru an injector. That's the reason for larger injectors so the same amount of fuel can flow with the same pulse width.


If I am wrong someone correct me.


T
NYEdited by: GMC-2002-Dmax
 

·
Registered
Joined
·
448 Posts
Tony,


To my knowledge all electronic injection systems in use increase fuel by increasing the dwell time of the injectors. Both gas and Diesel. I believe the failure point of the gas injectors comes from having the injector solenoid "on" for long times, this leads to overheating the solenoid by exceeding it's duty cycle and the injector fails due to electrical current being pulsed for too long. I believe our Diesel injectors work in a similar fashion, the most noticable difference I guess being that due to the extreme pressures that fuel is re-routed in the injector by the solenoid and fuel pressure is what opens the injector.


I think also that larger injectors would allow more fuel in a shorter time thereby allowing timing to stay closer to optimum so that larger injectors should make more power than stock ones can by staying open longer. The ideal of course would be for all the fuel to instantly appear at just the right moment. Not possible of course, but I believe that the farther past TDC that the piston is that there is a decrease in power that more fuel gives. Of course gas engines don't have this issue in that they are not direct injected, they spray fuel onto the back side of the intake valve and this fuel is allowed to accumulate until the valve opens, so that you can push the dwell time on a gas injector until it fails electrically, but I don't think that the dwell time on a diesel injector can be any where near as long, But I don't know what it's duty cycle is either. Has this made sense or have I botched up what I'm trying to say?
 
1 - 4 of 4 Posts
Top