Quote:
Originally posted by VTEC_boi
So..the less aggressive the cam..the lower the static compression? or higher?
|
Read the edited post above. You replied too fast.
Nope. The less agressive the cam, the higher the dynamic compression gets. Conversely, the more agressive the cam, the lower the dynamic compression goes. That's why you can make a 15:1 static compression engine run great - it has a very long cam and input flow restrictors. Static compression is not changed at all by the cam - it only cares about the swept volume (bore x stroke) and the combustion chamber volume (left over space when the piston is at TDC).
The cam choice and static CR should be intimately matched. Many good builders start with the cam, then calculate the static CR necessary to hit their target IMEP. Just adding more and more duration to a cam at a fixed CR is a losing proposition - you'll lose IMEP, thus volumetric efficiency, thus power. Conversely, if you keep adding static CR without changing the cam, you'll quickly increase IMEP to the point where you start to detonate.
Like everything with automobiles, it's all a magical balancing act...
