Reply to thread

Message: [QUOTE="TARM, post: 311598, member: 578"] OK here is the break I think some wanted to see for what the actual injection windows look like. This is the window that is based on what the crank/piston/cylinder allow. You can then, if needed, compare this to what the IDM limits are. You will see why the IDM limits do not come into play in any reasonable RPM limits of even top end diesel setups compared to the actual engine mechanical limits as are created by RPM rate. IDM limit is only that it can not have a overlapping signal. To help I will grab a quote from something Bill posted a few years ago. This will allow the two windows to be put side by side to see where they fall as the rpms get higher and higher. I am attempting to break this down in the way I found it easiest to explain. First thing was to take a specific RPM and calculate what the actual milliseconds per degree of crank rotation is for that rate is. I am taking this all the way down so it should allow the more people to follow it. It is not meant as a insult to the intelligence of those who understand all of this as some or all of this may be very redundant for some. We start with RPM (revolutions per minute) convert that to RPS(revolutions per second) then further convert that to RPMS (revolutions per millisecond). Then compute that figure to get ms(milliseconds) per degree of movement based on a 360 degree rotation. So basic formula of: 1/{[(RPM/60)/1000]*360}= ms per degree In speaking with Matt he gave me what he considered "Aggressive" levels of SOI (Start of Injector) advance for BTDC (Before Top Dead Center) and a rate to work with some advance rate for inside these rpms limits. I hope I got this correct Matt. There is always the chance I miss understood what you were telling me. But that can all be fixed if need be. Then there is the standard window that starts @ TDC (Top Dead Center) till the point where the injection spray can no longer be kept inside the piston bowl. This comes to 24 degrees from TDC. Lastly, we have "Injector delay". This minimum is a fixed time figure. As it deals with a actual time delay between when the IDM sends the signal to fire the injector to the moment of the injector firing (spraying fuel). It's not computed by crank degrees but actual time i.e. milliseconds. I still put down what the degrees would be as well as the percent the delay is of the entire window. With the break down it will also show the difference between commanded PW (pulse Width) window (delay included) and actual window (without it). These figures are all being used to create what can be considered a "maximum" injection window. I am trying to put this forth as with in reason what the largest possible window can be used for injection. Then having it all broken down so it can be easily seen where it all comes from. The chart is broken down by RPM starting @ 2000rpm up to 5000rpm in steps of 500rpm. Next to it will be the MS per single degree of movement. Then BTDC degrees and MS for SOI advance TDC degrees and MS. Injector Delay MS and its % of the whole. Finally total degrees PW, then total MS which included the 0.7ms delay for the full commanded PW window that is available. I could add another line to include what the delay adds up to in crank degrees added into the other total crank degrees to give a final on that adds up to all the ms of window if someone would find that helpful. I saw no reason as that is not how the delay is factored. Its already there so all someone has to do is just add the two together if they want it. RPM--------------MS/Degree---------°BTDC = MS-------------24°ATDC------Total Window °/MS----Delay 0.7ms=°/%----Total Comd Window:MS 2000 rpm------0.08333 ms/°------10.0°=0.8333ms------1.99992ms------34.0°/2.83322ms------08.4° / 19.81%------------3.53322ms 2500 rpm------0.06667 ms/°------12.5°=0.8334ms------1.60008ms------36.5°/2.43346ms------10.5° / 22.34%------------3.13346ms 3000 rpm------0.05556 ms/°------15.0°=0.8334ms------1.33344ms------39.0°/2.16684ms------12.6° / 24.42%------------2.86684ms 3500 rpm------0.04762 ms/°------17.5°=0.8334ms------1.14288ms------41.5°/1.97623ms------14.7° / 26.16%------------2.67623ms 4000 rpm------0.04167 ms/°------20.0°=0.8334ms------1.00008ms------44.0°/1.83348ms------16.8° / 27.63%------------2.53348ms 4500 rpm------0.03704 ms/°------22.5°=0.8334ms------0.88896ms------46.5°/1.72236ms------18.9° / 28.90%------------2.42236ms 5000 rpm------0.03333 ms/°------25.0°=0.8333ms------0.79992ms------49.0°/1.63317ms------21.0° / 30.00%------------2.33317ms --------------------------------------------------------------- Taking the above IDM PW Signal Window Chart and adding a row for Mechincal PW window RPM------PW ms@80%DC 3000------4.000----------2.86684ms 3250------3.692 3500------3.429----------2.67623ms 3750------3.200 4000------3.000----------2.53348ms 4250------2.824 4500------2.667----------2.42236ms 4750------2.526 5000------2.400----------2.33317ms 5250------2.286 5500------2.182 5750------2.087 6000------2.000 Let me know if I got something wrong or there are any changes that need to be made. [/QUOTE]