|
Lets say the cam sprocket has 24 teeth. Every tooth would be 15 degrees, but then you must double that amount since the cam is turning at half the RPM of the crank (30 degrees effective).
To make one tooth 10 degrees, the sprocket would need at least 72 teeth or some multiple of that.
Making blank statements about the effect of cam timing, must include the duration of the cam timing before assumptions are made about the effect of the opening and closing point of the valve.
If the valve opens after TDC then compression is effectively reduced, if you are talking about valve opening at precisely TDC which is seldom the case. Inertial forces of the incoming air charge, the inertial forces of subsequent charges and the harmonization of those charges all effect the total volume of that charge. Other factors like bore to stroke ratio, and exhaust tuning also affect the efficiency of the volume of the intake air charge.
EGR percentage, as well as residual exhaust gases remaining (effectively uncooled egr) also are changed when you change dimensions outside of the opening and closing of the intake valve.
Overlap of the intake and exhaust valve closing (intake) and opening (exhaust) will change significantly when intake valve timing is changed by whatever method.
regards
mech
|