Lobe aggressiveness and valvespring selection
08-02-2009, 02:06 AM
#1
Lobe aggressiveness and valvespring selection Alright hopefully this is advanced tech...
Lazy lobes (Comp Magnum we'll say) don't need much spring pressure to control the valvetrain. Aggressive lobes (Comp XE-R?) require much more spring pressure to control the valvetrain. So where does the size of the cam (duration wise) fit into the valvespring requirements? Lets say we have a 260/260 adv duration cam with XE-R lobes. Then we have a 310/310 adv duration cam with XE-R lobes. Assuming a proportional amount of lift increase on the larger cam, how does the spring requirement change? Is it strictly the shape of the lobe that determines the spring, or does the overall size of the lobe (same shape though) change things?
Sorry if the question has a lot of generalities, I'm on the LT1 side of things and don't know any common LS1 grinds to put things in perspective.
Lazy lobes (Comp Magnum we'll say) don't need much spring pressure to control the valvetrain. Aggressive lobes (Comp XE-R?) require much more spring pressure to control the valvetrain. So where does the size of the cam (duration wise) fit into the valvespring requirements? Lets say we have a 260/260 adv duration cam with XE-R lobes. Then we have a 310/310 adv duration cam with XE-R lobes. Assuming a proportional amount of lift increase on the larger cam, how does the spring requirement change? Is it strictly the shape of the lobe that determines the spring, or does the overall size of the lobe (same shape though) change things?
Sorry if the question has a lot of generalities, I'm on the LT1 side of things and don't know any common LS1 grinds to put things in perspective.
08-02-2009, 10:14 PM
#2
FormerVendor
The spring needs to work with the lift and the valve speed. You need more spring load to control the valve the faster it goes and the spring needs to be setup so it can accomdate the lift you have.
Alright hopefully this is advanced tech...
Lazy lobes (Comp Magnum we'll say) don't need much spring pressure to control the valvetrain. Aggressive lobes (Comp XE-R?) require much more spring pressure to control the valvetrain. So where does the size of the cam (duration wise) fit into the valvespring requirements? Lets say we have a 260/260 adv duration cam with XE-R lobes. Then we have a 310/310 adv duration cam with XE-R lobes. Assuming a proportional amount of lift increase on the larger cam, how does the spring requirement change? Is it strictly the shape of the lobe that determines the spring, or does the overall size of the lobe (same shape though) change things?
Sorry if the question has a lot of generalities, I'm on the LT1 side of things and don't know any common LS1 grinds to put things in perspective.
Lazy lobes (Comp Magnum we'll say) don't need much spring pressure to control the valvetrain. Aggressive lobes (Comp XE-R?) require much more spring pressure to control the valvetrain. So where does the size of the cam (duration wise) fit into the valvespring requirements? Lets say we have a 260/260 adv duration cam with XE-R lobes. Then we have a 310/310 adv duration cam with XE-R lobes. Assuming a proportional amount of lift increase on the larger cam, how does the spring requirement change? Is it strictly the shape of the lobe that determines the spring, or does the overall size of the lobe (same shape though) change things?
Sorry if the question has a lot of generalities, I'm on the LT1 side of things and don't know any common LS1 grinds to put things in perspective.
09-06-2009, 09:34 PM
#6
simple
get a function of the valve lift by nomial regression and fourier, multiply by rocker arm ratio, derive twice to get acceleration curve, drive one more time and set =0 to find max accel, use that acceleration in newton's laws to find total load at some rpm................................
add some safety factor.
dun.
get a function of the valve lift by nomial regression and fourier, multiply by rocker arm ratio, derive twice to get acceleration curve, drive one more time and set =0 to find max accel, use that acceleration in newton's laws to find total load at some rpm................................
add some safety factor.
dun.
