Originally Posted by
scottt28
Ok. Skies are parting. This is more of a a commentary than a question...
Let's say that "IVO" is 18 degrees BTDC using Mowton's example. "IVO" in quotes means that intake valve STARTS to open at 18 BTDC. That's the point where the valve comes off the seat, but it is nowhere near full lift. I'll bet that full lift probably doesn't occur until 80-90 degrees or so later depending on the ramp profile. We never go from full closed to full open with nothing in between. Further, we know that ramp profiles on hydraulic cams versus solid cams, versus solid roller cams versus hydraulic roller cams, are different. We could also assume that opening ramp profiles are different than closing ramp profiles on the same lobe - and intake lobe ramps are different than exhaust lobe ramps. Ramp profiles are probably well guarded, but with the right equipment and enough time, we could map the intake/exhaust lobe opening and closing ramp profiles (assuming they are different). Using duration and the ramp profiles, we could come up with a total area under the "lobe curve". We could also map movement at the actual valve based on rocker arm ratio and design. I'll bet that the shape and size of the area under the "lobe curve" is different than the shape and area under the "valve curve".
Log files will show us the injector pulse width (with a certain injector size/design moving fuel at a certain pressure) required to achieve the desired AFR at a specific engine RPM/load/ECT/moon phase etc. Right?
If all that is more or less true, then the question becomes when to fire the injector knowing that injector takes X milliseconds and Y degrees of crankshaft rotation to fill the cylinder in such a way to achieve the desired AFR at a specific engine RPM/load/moon phase etc.,
I wonder if you fire the injector too soon, will you upset the spray pattern? You might be washing down the lower part of the intake or the intake port in the head (depending on injector location and spray pattern). The whole deal might hit the valve stem and puddle on the backside of the closed valve. Maybe it puddles up between the closed valve and the seat. Maybe half the shot hits the valve margin and the rest hits the top of the piston. Maybe the whole mess bounces off the top of the piston and out the exhaust port past an open exhaust valve.
Ed M. - I am working on your spreadsheet to make it a little more user friendly. I'm thinking that it'll be easier to document and test various settings rather than getting a PHd in mechanical engineering, fluid dynamics, physics etc...