Turbo Kyle

iTrader: (33)

What is the rocker ratio on the Evos? Im trying to figure out lift at the VALVE. For instance the Cosworth M3 intake cam has a lift of 11.6mm witch is .456 in inches...so if the rocker is a 1.5 ratio then .456 X 1.5 = .685 lift at the head? Or is the 1.5 already configured into the spec .465/11.6mm at the head?

mike 99gsx

Cam companies usually spec their lifts as valve lift already factoring in the rocker ratio.

Turbo Kyle

iTrader: (33)

Thats what I figured...thanks

Aby@MIL.SPEC

iTrader: (161)

oem rocker ratio is 1.73:1

advertised valve lift is figured in using the ratio of the rocker, since the rocker helps to open the valve.

to figure lift of a particular cam, measure the tall portion of the cam lobe, subtract the narrowest portion of the cam lobe (base circle) = cam lift * rocker ratio = valve lift....minus any lash, which can vary due to cam maker & cams that are hydraulic or use mechanical adjusters

Turbo Kyle

iTrader: (33)

Thanks Amigo..I was just wanting lift at the head. Wanted to see what the number was...Im a domestic fella so I want to know what LIFT my M3s were 456 doesnt seem like that much...but it probably is considering the motor size

Aby@MIL.SPEC

iTrader: (161)

the difference comes from opening 2 intake / exh valves vs. 1 of each!

Turbo Kyle

iTrader: (33)

^ haha did think about that