Quote:
Originally Posted by Blokatos
That is an opinion and I can respect that. However, a 280 duration 11 mm lobe may have more clearance than the 13mm - 240 degrees one depending on how the ramps are ground.
|
But how can the ramp rates have that much affect on the low lift of symmetrical (or very close to symmetrical) profiles when there is a 40 degree increase in that example? Assuming symmetrical then you will be opening 20 degrees earlier and closing 20 degrees later for the same lobe centre. Therefore the 280 cam has a far tighter clearance than the 240 regardless of peak lift at the critical point.
Some cam profiles run very fast opening inlet and fast closing exhaust to minimise overlap whilst having good area but those kind of profiles are found on finger followers in high end race engines, not something like an FA20.