Difference between LT1 & LT4
Safety Car
Joined: Aug 2008
Posts: 4,344
Likes: 48
From: San Marcos CA
The small amount of lift a 1.6rr adds will not equate to 15rwhp. Most of the hp gained from a cam is in the duration not the lift. I even spoke to Lloyd Elliot about this in the past.Think about it this way- lets say a particular valve and port combo only really flows any decent amount of air at .050 lift and above. With the higher 1.6 ratio, the valve gets to the .050 part sooner and hangs open a bit longer on the way closed so the open angle at and over .050" is more degrees of duration that with the 1.5 rocker. So take a tame stock engine like the LT1 that is starving for a bit more flow---easy money.
Last edited by mike100; Jul 4, 2016 at 11:28 AM.
Burning Brakes
Joined: Dec 2009
Posts: 1,143
Likes: 81
From: Finger Lakes Region, New York
increasing the rocker ratio always nets you more 'effective duration' even though the cam lobe is the same. The only reason to not over do it is for valve train durability issues.
Think about it this way- lets say a particular valve and port combo only really flows any decent amount of air at .050 lift and above. With the higher 1.6 ratio, the valve gets to the .050 part sooner and hangs open a bit longer on the way closed so the open angle at and over .050" is more degrees of duration that with the 1.5 rocker. So take a tame stock engine like the LT1 that is starving for a bit more flow---easy money.
Think about it this way- lets say a particular valve and port combo only really flows any decent amount of air at .050 lift and above. With the higher 1.6 ratio, the valve gets to the .050 part sooner and hangs open a bit longer on the way closed so the open angle at and over .050" is more degrees of duration that with the 1.5 rocker. So take a tame stock engine like the LT1 that is starving for a bit more flow---easy money.
