lobe separation angle

[Ape]

hi guys,
the last couple days i read through some articles about various cam timing events.
and how i understood there is quite some ambivalent info on the role, importance, of LSA, like one source says, one wants a close LSA for high rev appl. the other source says one wants a close LSA for low rev widespread power.
Well is lobe separation that important of a event anyways if one takes into consideration that the LSA is the product of when the cam needs certain timing events as an example IC what gets dictated by flow and rpm range factors?? i see the point of considering overlap as an important factor considering flowpotential and thus overlap time area. but with the LSA i would love a clearer picture since for me it is so far a compilation of single cam lobe events, thus resulting in a certain degree of separation of the two cams, rather than one so called factor that gets caused by other factors perhaps being more important??
Would you guys be nice so nice and shed some light on this issue, perhaps with an explanation why LSA is important, because thats what most of the literature excludes, and as said i would love to understand

thanks

christian.

[buddy rawls]

LSA is important only from the standpoint of manufacturing and assurity the cam is what you want. Trying to equate LSA to an explanation that applies globally is going to lead you to all sorts of misgivings. everything is completely dependent on the specific combination. whats wide for one may be narrow in another. In truth, the criticality of camshaft design lie in the valve events. The openings and closings and ramp rate. lobe separation is calculated from this data. not the other way around.

the openings and closings calculated in conjunction with the inlet and outlet flow parameters (flow, velocity, distribution), displaced cylinder volume and geometry, rpm, etc are where the truth is. Not in, is a 108 or 114 better.

A restricted set-up will require later exhaust events (depending on the flow capability), which narrows the LSA. Higher inlet capability will require earlier exh events, which widens the LSA. These are simply trends. Everything is relative. For instance a motor may be restricted at high rpms and not restricted at lower rpms. The valve event trends in the extremes of each case are quite different.

[Jay Allen]

To add to what Buddy has said, LSA is a by-product of proper intake timing and exhaust timing. The example I give is like this.

2 + 2 = 4, 2 being used as the IC and 2 being used as the EC. The product is 4.

Now, just say the number 4. How many different ways can you get to the number 4? Infinate.

I have people call me all of the time and say they have this cam that works great. But it is ground on blah blah blah LSA. They want the SAME cam, but they want it on a 114 LSA or 116 LSA so they can *Spray It*! It doesn't work like that, at all.

Summing this up.......Look for proper centerlines and the LSA will be just fine!

Good Luck!

[Ape]

thank you very much guys

for the great info. basically thats what i assumed too, since i never bothered with LSA until it got more and more prominent. Its just every other magazine you open its LSA here and LSA there. So i will kepp doin it my way, looking at the ports, rpm range and some other parameters, dan trying to find a suitable IC2 and EO2 and let the resulting 4 be what it is the byproduct of more important events. funny how the somehow allways get in the magazines into the LSA discussion.
great so i can keep doin things my way.

thanks a lot

regards christian

[OldSStroker]

Congratulations guys! This is the only thread I've ever read anywhere where all the posters understand the relavance or dependance of LSA on valve events.

Every time we read another "LSA" thread, perhaps we should link this to clear up the issue. On second thought, most folks wouldn't buy it anyway, and they would just start cluttering up this forum with the same drivel.

Thank you.

[Ape]

Hey Jay,

i just fed looked thorugh your webpage:

you guys grind ohc´s too???
would you also custom grind??
what data would you need??
can i contact you for some questions without plugging the board with offtopics???

thanks

christian