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Message: [QUOTE="TARM, post: 142788, member: 578"] That makes sense but how does the need for that injection cone to stay inside the bowl? The reason I likely have these questions is because I have not played with hands on tuning for myself as I would likely be able to better visualize and understand looking at the files and tables. So what it comes down to is with slower rpms you are going to be injecting at less advance that what is the max you can hit the bowl as you have more time for the combustion event to go thru its cycle and only as rpms really start to get faster are you approaching the max number of degree you can fire the injector and have the spray still make it all into the bowl? Even if you set the injection offset table to zero, you would still have to increase the SOI with increased operating rpm even with an injector that had 0.00ms of lag in order to maintain the same cylinder pressure peak relative to TDC. Or conversely, you would have to reduce the SOI as rpm fell in order to keep the rods [i]inside[/i] the block.[/QUOTE] SO what is the maximum degrees you can have the piston at BTDC (statically) that when you fire the injector the spray cone will be contained inside the piston bowl? That of course is without the delay to fire from when commanded as well I guess the short period it takes from when the spray first leaves the nozzle holes till they arrive at the piston bowl. Those times obviously are going to change with rpms. I just want to know if I set it up statically into position what would be the position that if the injector was fired it would all go into the bowl? I would assume someone or plenty of people (injector manf and perf shops) have tested. No matter how fast the RPM you would never spray at a more degrees than that max static piston position that the spray is contained in the bowl correct? I can see once that is known that then we can compute everything else. I still think to do as you say, which I agree with, you have to have a way to monitor the combustion event i.e. CP sensor. You can know you are inside the physical limitations but to know you are "keeping the same CP peak" with all those factors that may not be perfectly accounted for you have to be able to see that curve in time,SOI etc... You would look to your actual CP curve to make your final adjustments while staying within those physical limits. [/QUOTE]