Sonic30ss

http://www.hotrod.com/articles/camsh...ted-explained/

turbom700

So if my brain is working right this morning for marine Applications one would want a large LSA!!! Correct? Better idle, less chance of revision,

liquidlounge

iTrader: (1)

I really am kind of surprised that nobody has tried an LSA north of 114 on this site (that I've ever seen anyway). Maybe most BBC cam cores are limited to narrower, sub 115 LSA's? I can certainly see some advantages for the guy who wants to run a bigger, but not real big cam with wet exhaust or silent choice and not suffer reversion at idle rpms.

Crude Intentions

iTrader: (1)

The 502 mag cam is a 115.5 LSA.

SB

iTrader: (1)

If this engine had less of a decent head (it has AFR's) you would see more of a difference between the different LSA cams.

Also, this was a dyno test, not in vehicle test. I can tell you, that with a pre vortec SBC and factory type heads, the difference between a 110 and a 114 (otherwise same cam0is pretty eye opening - on road performance. 114 quite lethargic, 110 or less quite peppy. In fact, thumb thru a catalog and you'll see sections where there are 104-106LSA cams...you won't find this on BBC sections.

Lastly, the more overlap you have (tighter LSA's and/or more duration) the more important tuned exhaust is important.

The article did mention this, but easy to miss:

Sonic30ss

I agree about the "peppy" part, the engines ability to accelerate is better with the tighter lsa. I had a 106 lsa solid in a 440 mopar with a Wieand tunnel ram six pac intake that ran like a raped ape over 2500 but had so much reversion below 2500, the intake ports were black an inch or two into the intake...instant death in most boats unless you had dry pipes or tractors.

I guess the point is, in the marine world since we aren't drag racing and engines are subject to constant load, is the "peppyness" worth the risk of reversion for a few extra hp that you probably won't see on the speedo or would you rather have a big fat, flat torque curve without worrying about killing your boating season and your wallet?

SB

iTrader: (1)

This has to do a lot with the exhaust. Again, less LSA and more overlap requires more attention to the exhaust for things to work better. Black intake ports shows a need for better exhaust attention with this lower LSA.

Sonic30ss

Yeah I'm sure the plenum volume of that rat roaster intake and lack of air speed didn't help either- it didn't like being corked up -1 3/4 header and 2 1/2 exhaust ��, even uncorked at the track it was soft below 2500 and at 3000 would burn the tire off it so leaving with a 4 spd was a challenge...good times and memories though...

5050

I love my 114 LSA. .714 .714 sr 260 266 @.050 and idles decent. 114 helps idle quality but there many factors. Big motors like wider lsa. [ATTACH=CONFIG]565117[/ATTACH] naturally aspirated tall deck

MILD THUNDER

iTrader: (3)

Lobe separation angle, is simply the result of valve timing events.

The engine does not know the difference between a 108, and a 114 LSA. It only sees the result of when the valves are opening, and closing. That changes, with duration, intake centerlines, exhaust centerlines, and so on.

A cam with a 114 LSA, may have a 110ICL. Also referred to as, 4* of advance built in. A cam with 108 LSA, might have an ICL, of 106*, or 2 deg of advance built in. What changes, is the valves opening and closing points, assuming duration hasn't changed.

As stated, overlap, is what matters. 114 LSA, doesn't mean you'll have less overlap, than a different cam, that has a 110 LSA.

A good example, would be, the HP500 cam, vs the 525 EFI cam. The HP500 cam, has 110 LSA, and 525 EFI cam, has 114 LSA. However, OVERLAP,

HP500=5* overlap

525EFI = 12* overlap

The HP500 cam, is a 222/230 110 LSA. The 525 EFI cam, is 236/244 114 LSA.