ok what do these mean again Advertised Duration Duration @ .050" Gross Lift w/
1.6 int /1.8 ext


Stock Specs for D16Y8 SOHC VTEC (96-up) 288 / 292 218 / 204 397 / 367
Stock Specs for D16Z6 SOHC VTEC (92-95) 304 / 303 212 / 204 394 / 373

if i am thinking correctly a z6 cam looks like a better cam or am i not reading it right

 

The first set of numbers (lets use the D16Y8 as an example) are the seat-to-seat duration, in this case 288 crankshaft degrees for the intake and 292 for the exhaust. This is measured from the instant the cam hits the rocker with valve lash adjusted properly.

The second set of numbers is the duration in crankshaft degrees measured when the valve is lifted .050".

The third set of numbers is the gross lift. This is the lift and is the difference between the base circle and the highest lift point of the cam. Actually the valve lift will be slightly less because you have to take into account valve lash.

A lot of guys and some cam companies will only give you specs. at .050" valve lift. These are relatively useless numbers. The ports are flowing significant amounts of air at .050" valve lift. Two cams can have the same duration at .050" lift, yet their seat-to-seat durations can be quite a bit different.

Even the guy who made up the .050" valve lift spec. admits it was supposed to be used in conjunction with seat-to-seat numbers.

The second cam has more intake and exhaust duration. They don't give lobe centers so I don't know how much overlap it has but it would be better for a higher rpm, higher compression engine.

These cams are for different engines anyway so you're kind of comparing apples with oranges here.

-Scott Tucker