what makes the cam chop?

[SLOWBRAEATER]

Is it mainly the lobe seperation? I was listening to slacker69 cam and man it sounds mean as he**. His ls is 113 mine is 114 doesnt seem like a huge difference. do you guys think my cam will chop decent? .507 220/224 114ls 110 ic

[Dominic]

The cam chop is actually determined by the true valve overlap in degrees. Not the 112 or 114 number, but the calculated valve overlap number. Less Separation + more duration = More overlap.

[SLOWBRAEATER]

sorry im confused, so do you think my cam will chop good? will you be able to tell i have a cam in there? you said it should perform very well right?

[Roy]

i have 112 lsa on my cam and its noticeably more lopy than a car with a 114 lsa (same duration numbers). 113 to 114 isnt that big a difference, and that duration is huge for a v6 too.

[WickEdSix9838]

the bigger the lobe separation the less it will lope, thats why factory cams have such big lobe separations so it runs smooth

[ June 15, 2003: Message edited by: WickEdSix9838 ]</p>

[Dominic]

The valve overlap for a 210/220 112LS = 47°
The valve overlap for a 210/220 114LS = 43°

You see, just changing the LS by 2° you're changing the overall overlap of the valves (the time they spend open together) by 4°!

This value of how long the valves are both partially open is what determines how well it'll idle. And yes, a 220/224 is big... too big IMO.

[ June 15, 2003: Message edited by: Dominic ]</p>

[Magnus]

yea, 220/224 114 will definately chop. Probably peak pretty high too.

[wolf]

<blockquote>quote:</font><hr>Originally posted by Dominic:
The valve overlap for a 210/220 112LS = 47°
The valve overlap for a 210/220 114LS = 43°

You see, just changing the LS by 2° you're changing the overall overlap of the valves (the time they spend open together) by 4°!

This value of how long the valves are both partially open is what determines how well it'll idle. And yes, a 220/224 is big... too big IMO.

[ June 15, 2003: Message edited by: Dominic ]<hr></blockquote>

what the formula for that? I wanna figre out how many degrees of overlap my cam has.... 226*/234* dur. @.050, 108 LS

[SLOWBRAEATER]

Dominic, in one post you say that cam is really good and you cant really find anything to change for me to have a better cam for my car and now in this post you say its too big, why do you say its too big? I told dave buckshaw about it and he raised the rev limiter and adjusted shift points and raised idle so this cam works great for my car. thanks for the replys everyone i appreciate them all

[Dominic]

Well you said you're running a 220/224 right?

kinda big, not bad, but big [img]smile.gif[/img] I thought your cam was smaller than that, I think I had read it as a 210/214 or something. I might be wrong though, so don't feel bad. If it runs well and you're happy with it thats all that matters.

Any ETs yet?

[ June 17, 2003: Message edited by: Dominic ]</p>

[SLOWBRAEATER]

Its cool, i respect your opinions on cams thats why i asked and was kinda curious why you said its too big, i mean my rev limiter is raised so i can take advantage of the peak power higher up...

[Arctc Wolf]

lift should be based on how well ur heads flow, and duration should be based on the cylinder displacement. if you want max flow in and out of cylinders, you gotta figure out a balance. if you bored/stroked the motor out, and didn't want a ton of overlap, u could get more lift in the cam to make up for the airflow. if the heads didn't flow well at high lifts, and you still wanted max power, you could add more duration.

with our heads, lifts lower than .500" flow well through our heads, so to make more power w/ stock heads, you'd wanna add more duration to make up the flow difference.

the idea is to keep air velocity up while getting the max amount of air into the cylinders.