How does the lobe sep.affect horsepower? Would one with say 112 produce more power than a 115?

 

In general, opening up the lobe sep makes an engine idle better, have less low end torque, lower peak torque and HP, and spreads the torque band out mostly upwards. A lower lobe sep will have a rougher idle with lower vacuum, more low-end torque, a narrower curve in both torque and HP with higher peak values, and the power will die off faster as RPMs go above the peak.

 

Lobe seperation is basically how far apart the peak lifts are. The higher that number is the less overlap youll generally have. This cam would have a smoother idle and make power at lower rpms. A cam with a lower lobe seperation(gennerally more overlap) will generally idle rougher and make its power at a higher rpm. The key to making hp is to match all of the parts on your engine. If you have low rpm engine you wont want a cam with a lower lobe seperation because youll be out of the cams operationing range and visa versa.

 

A lower ( tighter) lobe separation cam will not have more low end torque. it will ( generally) have more peak torque and
generally more low/midrange torque. But the real low end will generally be less. (unless the cam is installed advanced)
The position of the cam in the motor makes a big difference. the biggest factor is the intake closing point.
This is affected by the cam lobe separation and the
cam advance.

The guidelines are too generalised. Most mild cams with
wide(r) lobe separation are more responsive off idle
and return better fuel mileage at cruiseing speed.
Also what works best with open exhaust may not be best for a car that has a full exhaust system.
Most of the charge scavaging pulses that are benificial
for power with a open tuned exhaust system (headers),
and lots of overlap (tight lobe separation numbers)
are dampened out by a muffled exhaust system.
May times the wider lobe separation cam works better
overall on a street car.
What works on a oval track or drag motor on the dyno
with open exhaust may times is not the best for a street car.
What is best for one cam duration and engine purpose is
not the best for another.
take the general guidelines with a grain of salt.
An engine system is going to want what it wants for valve timing points. Not what generalized thereory indicates.
Your faviorite Cam companies' tech line can help you work through the mysteries of LSA's and get you hooked up with the right cam for your car. The more acurate info you can provide the better the recomendation will be.
Not ever motor wants a cam ground on 110 LSA. or 112 or 106.