ramdaspadhye

iTrader: (3)

I wouldn't run a 114lsa, but that's just me. Peak power rpm is too high in a 5k lb suv

TX Tahoe Z71

iTrader: (28)

Get a Radix instead! I was thinking about a cam too, but figured I would just want more power in the future anyways

budhayes3

iTrader: (19)

I like the 206/212 or 212/218 that have already been mentioned, I have the 206/212 on a 114 and have been very happy with it as a daily driver without a higher stalled torque converter. Personally, I'd keep the LSA around 114-115 for the broader torque curve.

ForcedTQ

iTrader: (1)

I think you have the wrong idea here. The .050" number that is indicated is the amount of lift that is occurring when they take those specific duration readings. No matter what RPM the engine is running, the valve will cycle over the entire profile of the cam lobe, from .000" lift up to the max lift listed on the cam card then back to .000"

The combination of LSA, Duration, Overlap, and Lift will determine the width and peak of your engines power-band.

03 BLACKOUTSSS

iTrader: (3)

The numbers 206/212 are indicating the duration of time (in terms of 360* rotation of the crank) that the valve is open. The first # is the intake and the second is the exhaust. You'll notice that one of two things is going to be fairly standard across the board with cam recommendations you get. Either the lifts on both intake and exhaust will be the same, and the duration will be a bit longer on the exhaust side. Or you will see equal duration but the lift will be higher on the exhaust lobe. The reason for this is primarily to compensate for smaller exhaust valves, the higher lift (or longer duration) provides the engine with a little bit more time to expel spent gasses. This is done primarily with HP in mind...and it works.

Take a look at my sig...I went a different route. I have an intake biased cam, as opposed to the more accepted exhaust biased. This was a tough decision for me as its pretty much contradictory to what everyone suggested. I did alot of talking to alot of different people and made the decision to go with a 218*/214* .578in./.578ex. My intent was to make loads of TQ. I wasn't concerned with HP up in the RPMs because I don't spend alot of time there. I wanted monster TQ from idle all the way up. And I got it. I couldn't be more pleased. This thing just pulls hard all the way through the band. Second and third gear just keep going, its rediculous. IMO, thats what it sounds like you are looking for. Normal driving characteristics, decent mileage, strong power...

I did have to change the springs lifters and PRs though...there aren't many options that would enable you to keep the factory springs. Coil bind becomes an issue very quickly with too much lift on the stock valve springs.

ForcedTQ

iTrader: (1)

The numbers 206/212 are indicating the duration of degrees of rotation of the crankshaft that the valve is open. The crankshaft rotates 720 degrees for every 360 degrees of rotation of the camshaft. 2 to 1 ratio.

03 BLACKOUTSSS

iTrader: (3)

Thanks for correcting that, I felt like something was wrong, but I couldn't put my finger on it. That makes more sense.

tybardy

man this is AWESOME information... hope you guys dont mind if I keep going a little...

sounds like i am on the right road to understanding the duration of lift, but where does the LSA come into play as it seems to be an important number to consider when buying a cam.

also, what is that second string of numbers? (i.e. .578in./.578ex)

GMCtrk

iTrader: (27)

Take a look at this chart. This is some testing Hot Rod magazine did a couple years back on the 6.0 LQ9 motor. This is a graph of torque output. Notice the black line, that is the stock 196/207 cam. And then look at the light red line, that is the Crane 210/218 .531" 114 lsa cam. Notice it is the ONLY cam that makes more torque than the stock cam at ALL rpm values. The other cams in the test are all bigger, all the way up to 232/236. I have no experience with cam swaps myself for the simple reason that I've been unable to decide on what size to go with. Empiric data such as the above clearly shows that bigger is not better when it comes to cams, unless you want to rev past 5000 rpms to make your power. I would prefer that my power come on strong right off idle. Some might argue that a 3000-3600 rpms torque converter would help you get in the power band of a bigger cam, but you can see that even the small cam is making much more torque in the mid range. On the street, I think the smaller cam wins; I could understand the argument for bigger cams if you do a lot of racing or spend a lot of time in the upper RPM range. However, when it comes to posts like Nawlson's where he says that a cam smaller than 224 is a waste of time, I'm more inclined to not believe that given the dyno testing I am referencing below.

03 BLACKOUTSSS

iTrader: (3)

LSA has a few effects on the characteristics of the motor. First, and most noticably, is the idle. Typically the tighter the LSA, the more choppy the idle will be. Idle choppiness is also affected by valve overlap. Valve overlap is a point in the rotation of the cam in which both intake and exhaust valves are open and the air/fuel mix is allowed to go straight out the exhaust valve, and is calculated from by looking at the Intake Center Line and Exhaust Center Line. I don't have a solid grasp on all the pros and cons of valve overlap, but I know that a cam with less overlap will have a higher dynamic compression ratio (DCR) than a cam with more overlap. DCR is a function of the static compression ratio with outside air pressure factored in. A higher DCR will yeild more TQ and seeing as how HP is a result of TQ, more HP as well.

Second, a higher LSA (116 or 117) will broaden the power band, and move it higher in the rpms.

I am sure there are other things that the LSA affects, but I don't know them. Also, don't take what I said above as gospel, there are very likely a few inaccuracies in there.

Hope this helps.