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Message: [QUOTE="TARM, post: 139381, member: 578"] I think in actuality there is less real PW window available then those numbers Big Bore. Closer to .5 -1ms less. There is a fixed mechanical limit as far as degrees of crank angle period as is or should be well known and understood by now. We of course have a certain window of time to hit that window which decreases with increases in RPMs. The time window also has to be adjusted for the fixed .6-.7 ms of injector injection delay of actual SOI advance. Its also best to look at this is degrees of crank angle as we are trying to hit piston bowl. The delay is why commanded SOI degrees of advance has to increase with RPMS. Factor in a limit of say 28 degrees plus adj for injector delay and anything more you spraying outside the bowl producing that lovely tell tale star pattern on the piston face. Factor that if you like to keep your stock rods inside versus poking out of the block 24-26 degrees, from what I can figure would be a safe limit, without factoring in the injector delay, so real actual SOI. From what I have seen from feedback spraying after TDC might get you some additional power but basically it gives you mostly smoke and heat. Take 24 BTDC for SOI then factor in advance compensation for the injectors .6-.7 ms of delay. Say this is for 4K RPM. Even add in say 6 degrees of window for after TDC of injection event to include the .2 or so delay in cut off of the injection. Now factor that for time based on whatever RPM point. What you end up with @ 4K is basically 1 ms for every 24 degrees of crank angle. Then add in that .6-.7 ms for injector delay which amounts to about 16 degrees of advance @ 4K rpms. So a total of 40 degrees of BTDC plus a small amount of after TDC spray and or stop delay as insurance of covering the complete window so say 44-45 degrees. Now thats being a bit of conservative on hitting the bowl so you could likely add another 2-4 degrees to the actual SOI. The`limit with delay factored in is likely 44 degrees BTDC SOI (1.83ms@4k rpm)then add back in the small amount ATDC for a total PW of 48 degrees of PW or 2ms. Those are what would be seen as on an oscilloscope. IMO the above is why once you get to wanting to make real new power with a reasonably sized nozzle and injector setup and you want to gauge/compare injector flow performance from flow bench testing sheets you look at the 2 ms or at most a 2.5ms windows. That covers the 3500-4000 rpm range. To gain more useable power we need to be increasing the injection volume in the 2ms and under window and of actual injection from start to end of actual spray 1ms to 1.5ms window range. I am of course open to the possibility that my numbers and or computations are wrong but with out tons of hands on experience this is what I have come up with. Formulas to compute number of crank degrees there are per millisecond @ any specific rpm: [(Revolution Per Minute / 60)/1000 = Revolutions Per Millisecond]* 360 degrees = Crank Degrees per MS @ RPM [(4000 RPMS/60)/1000 = 0.06666 RevPerMS]* 360 degrees = 24 degrees of crank per 1 ms [/QUOTE]