what kind of power difference do you get from a close number lobe like 115/115 and a number like 110/120 duration? how does it effect the powerband?

 

A cam with "115/115" and another cam with "110/120" lobe locations have the same LSA {Lobe separation angle} of 115Deg. But the second one is advanced in the motor by 5 degrees. Advancing the cam in the motor (relative to the crankshaft) will increase bottom end and mid range torque a little and reduce top end peak horsepower output a little.
Mostly because the intake valve will close sooner when advanced.

Generally, advancing the cam a little results in better overall performance.

Generally, but not always, this slight advancing is built in to the cam during manufacturering.

 

I wouldn't advance a 115 LSA cam with a SR, there is no need and it will take away any advantage you would gain from the SR.
In fact you should change to cam to receive an advantage to at least 113 LSA.

 

All untrue.

 

SR?

So those two cams mentioned, are the same cam, just one would be advanced (degreed?) 5 degrees when installed?
Would this also make sense to get a cam with more overlap, in order to get higher lift, then advance it to bring the powerband back down lower?
(ie a cam with typically more lift would have more duration, and therefore works best at say 2200-7000RPM or something, if you degree it more advanced, could you get a 1400-6000RPM power band with high lift?)

 

In a word NO advancing the cam will not lower the basic rpm range of a cam. it just shifts or bias's the torque band a little enhancing the low end of the band. ( mostly because the intake valve will close sooner.

A big cam will still be a big cam. Advancing it won't make it a small(er) cam.

Overlap is a function of the duration and lobe separation of a cams intake and exhaust lobe. It is independent of lift.

Smaller LSA number= more overlap. A small LSA does not nessessarily mean more low end torque. it generally does mean more peak torque. Usually the overall power curve is peaker too. Race cams with tight LSA like 104-106 Typical of circletrack and auto trans bracket racing cams work best with open headers and merge collectors. These cams are typically installed 4 to 6 degrees advanced as overall torque and torque off the corners are more important than peak power.

A street car with a closed exhaust system needs something different.

 

Now that i'd have to disagree with, otherwise i'd be getting a .5" lift cam, with low duration for good street manners and lots of power, but without going to a roller setup.... I need some duration/overlap to get big lift.
*right?*

So if I wanted a large amount of low end torque, quite broad range, I would be better off with say, a comp 262, rather than a 268 advanced 4 degrees say?

And finally, keeping on the subject of the thread, A larger LSA would give a flatter, longer, more broad torque curve right? (and better idle characteristics?)

oh, and what's SR?

 

SR=Solid roller

A larger LSA does exactly what you said.

And yes a 262 would produce more low end then a 268 adv 4*. Mainly because it would not bleed off as much intake charge.

 

thanks guys, was curious!

 

Normally I'd think the same thing, but in this case it means Stealth Ram.

 

Ah, i see that now. Thanks for the correction.

 

Usually the stealth ram is refered to as the HSR.