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Message: [QUOTE="TARM, post: 311500, member: 578"] I feel the same way/ I could have worded that better. More than a ultimate curve I think there is a limit for the curve up top. You may be able to have a curve like I have posted but it can not keep going, obviously. It can only go till it hits a certain limit. Much like there is a ATDC limit of 24° after which you are no longer getting all the spray in the bowl. What I did find very interesting is when I used the numbers I posted for advance without knowing it before hand they actually worked out to end up being the exact same amount of time in MS for each RPM step. That is by multiplying the ms per degree for 2K 2,5K 3K etc going the off set of 2.5 degrees of advance for each 500 rpm step from 2K to 5K they all end up being the same amount of time in ms./ It worked out to be 0.8334ms/ So how is that for a coincidence? Here is something I was working on. We have a fixed .7 for injector delay. The fact that this is a static unchanging variable in commanded PW means that with each increase in RPM which causes a decrease in the available PW window time the delay becomes a larger percentage of the commanded PW. What this means when you also add in the BTDC SOI advance to the 25°@5K and go no further is the IDM limits actually hit much sooner than most think. Now this limit will never be an issue in useable RPM range even for a CR setup. The point is these limits that are time based take away from that amount. You can understand it better when you see a chart of it side by side. I am double checking my numbers and math. Once done I will post it up. I am sure others such as Bill Dave Matt have done this all long ago. But I think it could be helpful for others trying to understand and learn the limits of the system. I also while not being a tuner understand there is a injector or injection delay table. This is what is also used to deal with EOT delays as well as the base mechanical delay of the injector. In considering this and talking to other experienced tuners I found some try to use this delay for other control without understand its effect so you end up with an adding of additional delay time. That time works out to being effecting the start of injection as RPMs increase by more degrees per that time amount. [/QUOTE]