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About Fuel Injector Timing


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I have read lots of thread about injector timing but some of them confused me. 

I am tuning my cooper r53 gp and I realized something about injector timing. When I start tuning my car Inj timing was 330 BTDC and position is end of injection that came with base map. Then I calculated my camsaft timings and found intake valve opening 18 BTDC. And set my inj timing from the formula 360 - 18 = 342 BTDC then I made a few runs and realized that engine knock noise lower than before. And play with ignition advance knocking values with 330 degree isnt knocking with 342 degree. I can advance timing about 2 degrees with 342.

I am using 550 cc injectors and at max duty cycle i see is about %60. I think in this case injector timing matters.  But I dont know my settings right or not.

For a theory you have to inject all fuel right before intake valve open. But there is someting wrong with this theory before intake valve open exhaust valve is also open and fuel can go to the exaust without burning.

I think best time for injecting fuel is right after exhaust valve closed. But in this case I dont know is there enough time for injection fuel.

And my other question is why is vipec using 330 BTDC for Cooper S it doesnt match with stock cam specs.

In this picture left side stock cam and right side my schrink cam values. 

 

 

valve.JPG

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Injector spray pattern, injector location, port temp, fuel composition and fuel pressure will all have a significant influence on what is optimum for you.  You cant guess or calculate it theoretically, as what you are trying to acheive is find what conditions create the most usable volume of volatile fuel vapor.  You must do it by experimentation while measuring torque output.  Most engines it makes very little difference once engine speed is above about 3000RPM.  For idle and low speed you can determine it just by adjusting timing so that you get the richest measured lambda for a given pulsewidth. 

As rrob says, for a warm engine at idle with injectors close to the intake valves, common values will be 3-400deg.  For a cold engine/port usually much earlier timing is required - often around 200-300 is best.  

 

11 hours ago, cooperr53gp said:

I made a few runs and realized that engine knock noise lower than before. And play with ignition advance knocking values with 330 degree isnt knocking with 342 degree. I can advance timing about 2 degrees with 342.

Knock level is not really relevant - this could mean the exact opposite of what you are trying to achieve.  Less efficient combustion means lower cylinder pressure, less noise/knock and less torque.  

 

 

 

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