Injection Timing: how late can it be?
Hello everyone, I was wondering how to improve engine power/efficiency by tuning the injection timing and found out that some studies claim the best power can be obtained if peak cylinder pressure happens arround 15º ATDC.
Looking at SOI/duration maps, injection ends before TDC, so pcp will be much earlier.
How long do you people recon that fuel takes to start burning after injection? I've seen claims that high cetane (55) diesel will start burning in about 0.4ms on a modern diesel. If this is correct, why is fuel not being injected much later?
For example at 4500rpm, soi (for my 2.4 200hp engine) is 28.5º BTDC, won't diesel start burning so soon (arround 18º BTDC maybe?) that it will make a lot of negative work on the piston? Wouldn't a SOI of arround 10º BTDC mean combustion started arround TDC and improve performance? (much less negative work?)
Does anyone run with this kind of late injection?