injector duty cycle vs atomization
injector duty cycle vs atomization Is it better to have your injectors close to maxed out so they spray fuel evenly throughout the whole intake charge, or if it would be better to have oversize injectors so you can spray the majority of the fuel at a certain time, like when the intake valve opens.
Or put another way, is it better for fuel atomization to have high injector duty cycle or low duty cycle?
Or put another way, is it better for fuel atomization to have high injector duty cycle or low duty cycle?
great question! i think this is mostly a question of balance, you dont want it too low on atomization, but you dont wanna overwork the injectors either. at the same time, you gotta remember that at lower rpm your duty cycle is gonna show much lower numbers, but it doesn't mean it's atomizing it less because of it, the pressure supplied is still the same. gotta remember that rpm's dont change the duration of the fuel injection itself, but only changes the 'window of opportunity' to do the injection in. the actual flow is dependent only on size of the injector and the fuel pressure. so i'd guess atomization has to do a lot more with fuel pressure than the duty cycle.
or i might be completely wrong, i'm just 'thinking out loud' here
or i might be completely wrong, i'm just 'thinking out loud' here
The pressure in the port is changing with the movement of the air and the intake valve. But maybe "atomization" was a bad choice of words. Seems like you would end up with a different distribution of fuel in the cylinder if you injected the fuel in one short burst instead of the injector staying open the whole time.
yep...
Originally Posted by GIGAPUNK
I've only heard of atomization being dependent upon pressure.
The duty cycle, usually, has no effect on the pattern. [I can choose cycles from 3ms/800rpm, to as much as 12ms/10,000 rpm.
I do see some "lazy" patterns on the very large injectors, such as 160#... But, those injs are showing a "fire hose" type spray, anyway.
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Staging Lane
Joined: Mar 2006
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And just to dispel a possible myth that you may believe, Sequential injection is designed to spray on a CLOSED intake valve. The fuel that reaches the valve will absorb some heat (vaporize too), and then when the valve cracks open, there is a nice blast of exhaust to blow the wet fuel into iddy biddy pieces also. If you spray mostly at an open valve, your atomization will suffer greatly, and the burn will be terrible. Yes, I've tested it.
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Originally Posted by RednGold86Z
And just to dispel a possible myth that you may believe, Sequential injection is designed to spray on a CLOSED intake valve. The fuel that reaches the valve will absorb some heat (vaporize too), and then when the valve cracks open, there is a nice blast of exhaust to blow the wet fuel into iddy biddy pieces also. If you spray mostly at an open valve, your atomization will suffer greatly, and the burn will be terrible. Yes, I've tested it.
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Originally Posted by RednGold86Z
And just to dispel a possible myth that you may believe, Sequential injection is designed to spray on a CLOSED intake valve. The fuel that reaches the valve will absorb some heat (vaporize too), and then when the valve cracks open, there is a nice blast of exhaust to blow the wet fuel into iddy biddy pieces also. If you spray mostly at an open valve, your atomization will suffer greatly, and the burn will be terrible. Yes, I've tested it.
Originally Posted by P Mack
In that case wouldn't it be better to have an injector that's large enough to spray all the fuel before the intake valve opens?
Injector timing is more important than duty cycle. At least thats what I make of it. Staging Lane
Joined: Mar 2006
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A typical factory sequential injector is sized to be about 60-65% (or even less) max duty cycle. Guess what the "duty cycle" is of the closed-time of the intake valve?
But, injector timing becomes LESS important at full throttle. It's still a little important, but there's tons of flow and turbulence/swirl/etc to get OK mixing. The batch fire systems of the 80's and early 90's didn't have too much problem with it, but sequential is better from an emissions and combustion stability standpoint throughout all operating ranges.
Another good reason for larger injectors is the cold starts at -40°C (or °F), where the PW is ginormous. But, probably no one on here will really want to try that with their sport car.
But, injector timing becomes LESS important at full throttle. It's still a little important, but there's tons of flow and turbulence/swirl/etc to get OK mixing. The batch fire systems of the 80's and early 90's didn't have too much problem with it, but sequential is better from an emissions and combustion stability standpoint throughout all operating ranges.
Another good reason for larger injectors is the cold starts at -40°C (or °F), where the PW is ginormous. But, probably no one on here will really want to try that with their sport car.
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Originally Posted by P Mack
Is it better to have your injectors close to maxed out so they spray fuel evenly throughout the whole intake charge, or if it would be better to have oversize injectors so you can spray the majority of the fuel at a certain time, like when the intake valve opens.
Or put another way, is it better for fuel atomization to have high injector duty cycle or low duty cycle?
Or put another way, is it better for fuel atomization to have high injector duty cycle or low duty cycle?
https://ls1tech.com/forums/pcm-diagnostics-tuning/201234-when-does-injector-pulse-start.html
https://ls1tech.com/forums/pcm-diagnostics-tuning/125236-tuning-ace-s-c-mon-debate.html
