Camshafts, idle quality, driveability and LSA-REAL WORLD EXP and OPINION

Ben Drinkin said

So a 'tight' lsa while keeping duration in check doesn't kill DCR? I assumed that in general, the tighter the lsa, the more overlap (both valves open) and the lower your DCR.. i got lots to learn! Been following these crazy threads trying to get educated. Seems the more i learn, the less I know!

Click to expand...

Tighter lsa = more DCR. This is because compression doesn't start to build until the intake is closed. Tighter LSA closes the intake sooner = more dcr. There is more overlap. Which is good for scavenging (exhaust pulling out burn carbon, and helping flow fresh air in). But with the tighter lsa the intake closes sooner into the compression stroke (because it's close to the exhaust stroke). Building higher cylinder pressure.

If any of that makes sense. I can have a hard time describing things sometimes.