fastrc

iTrader: (7)

Sorry it this seems a dumb question, still learning this technical stuff.
I often see cams with an LSA of 110 + 2 or 112 +3 etc.

What does +2 or +3 after the LSA mean ?.

Thanks for your help.

bad95killer

https://ls1tech.com/forums/generation-iii-internal-engine/870231-cam-advance-confusion.html

peace

fastrc

iTrader: (7)

Thanks bad95killer, I searched the forum but didn't find this thread.
Good reading.

How would the engine manners alter with a cam installed of LSA 112 +1 versus 112 +4.

1 FMF

iTrader: (1)

+4 is 4 degrees advanced, +1 would be only 1 degree advanced or 3 degrees retarded from +4.
Retarding cam timing results in all valve events happening later.... advancing the cam results in valve events sooner.
the most influential valve event is intake closing, by retarding cam timing the intake closes later and since duration does not change cylinder pressure will bleed off as the piston comes upward with intake valve still open, result is less cylinder pressure = less torque at low rpm.

they should do away with LSA because it is dependent upon duration.
there should only be duration and centerlines for intake and exhaust.

fastrc

iTrader: (7)

To conclude am I correct in saying that a 112 +4 deg LSA will give me more torque than a 112 +1 deg LSA ?.

I'm looking at two custom cams for an LS2, will I notice much difference in on road performance between the two.
1/ 228/228, 588/588 112 +4 LSA
2/ 228/228, 588/588 112 +1 LSA

All opinions appreciated.

Tom@SpeedInc

iTrader: (5)

Not really

Look into how valve events affect intake centerline

If you were to move ICL it will change your IVO and more importantly IVC, thats largest effect and move you exhaust centerlines. Thats modifying a camshaft backwards.

Constantly i'm asked, can you take this cam 112ºLSA and put it "on a" 11X, my response to that is, of course, did you look at the valve events of that? its a rhetorical question, the answer is no 10/10. NHRA Pro stock engines have in the area of 117º LSA, so LSA is mearly a 'by product' of the valve events.

camshaft #2 should show more usable RPM and potentially higher peak hp.

fastrc

iTrader: (7)

Thanks Fraser.
So which cam will offer more bottom end, 1 or 2 ?.

Tom@SpeedInc

iTrader: (5)

IMHO you won't see nor feel a difference between those cams under the curve, I think cam 1 will peak sooner and limit peak power, it will drop off at 6200

Camshaft #2 will run out to 6500rpm and have potential for higher peak number

LS1 dyno graphs peak tq at 4800rpm, no camshaft is going to slide that to 2000rpm for a peak tq.

by the numbers at .050" lift

camshaft #1
IVO 6º
IVC 42º
EVO 50º
EVC -2º

Camshaft #2
IVO 3º
IVC 45º
EVO 47º
EVC 1º

FootLbs

iTrader: (7)

I chose to retard my cam.

Therfore it made the power curve HIGHER in the RPM range.

Old SStroker

There is a common word for folks who arbitrarily retard a cam....but I won't mention it.

Impls425

my stock cam is 197/197 .286/.286 @ 114 LSA for LS4 i am boring my motor to 5.7 and replacing cam with 224/231 .332/.338 @ 113 LSA? what kinda gain do u think this will produce?

3timeracin

iTrader: (15)

You want the cam events to happen at certain points in the piston cycle to create velocity, compression a certain power band for your given application. The same cam in the same size engine but with 2 different length connecting rods will perform differently by a vast amount just because valve events happen at different point of the piston movement. read this article its one of the best by David Vizard http://www.hotrod.com/techarticles/e...ech/index.html

3timeracin

iTrader: (15)

depends on compression, intake, exhaust bla bla bla , most likely around 35hp