another question. assuming all else same (ie identical duration and lifts), between two cams, but one on a 112 LSA and one on a 114LSA, which one will have more top end power? i know the 114 would keep the intake valve open a bit longer and this would better fill the cylinder with intake charge. but the 112 LSA will close the intake valve sooner and allow for better cylinder pressure to be built up. so which (all else equal), would make better (peak) top end numbers?

 

lobe seperation angle does not effect durration

however, smaller LSA #'s = more peak and high rpm hp

 

i know this, i didnt mean to imply that it did, sorry.

if so, then why do cams for pure race cars (that spend most of their time in the high RPM range) use really tight LSAs, like 108, if it wont have as much top end power? i know tight LSAs have awesome midrange, but race cars use top end HP on most of the time right? what gives then?

 

Generally, a cam with a longer LSA will have both more top end and more bottom end, one with less will have a fatter midrange/taller peak.

WRT to what race cars use, that depends on the car. Circle track cars may use LSA’s as small as 106, where something like an indy car will often have an LSA in the 116-118 range.

Again, the question isn’t the LSA, the question is to get the event timing right and you will end up with an LSA…

 

makes sense, thanks mark.