mr08353

I've "heard" the max duration for an LS3 is 240 without valve reliefs in Pistons. Yet I see a lot of people running the BTR stage 4 cam. The advertised exhaust duration for that cam is 248. WTH? How's that work? Is 240 the max or not? Anybody know where these numbers (max lift and duration) can be found?

Mavn

iTrader: (3)

Duration doesnrt mean anything. its all I the Lift

KCS

iTrader: (20)

Wrong on both accounts. The valve and piston are nowhere near eachother when the valve is at max lift. Duration doesn't necessarily indicate PTV either but it can help calculate the important information if valve events are unavailable.

It's mostly about the valve events as the piston approaches TDC and as the exhaust valve is closing and as the piston leaves TDC and the intake valve is opening. This area is known as overlap.

KW Baraka

iTrader: (7)

Which means that you need to have more than JUST the intake duration to determine if PTV clearance will be an issue.



Also, mr08353, advertised duration is different (higher) than duration @ .050 lift, and it's @ .050" that most of us on the forums measure our cams.

That having been said, the specs for the BTR Stage IV cam at .050" is 235/242 degrees, intake/exhaust.

KW

mr08353

Makes sense. Thank you sir.