Cam Difference

[GEE8GEETEE]

What is the difference between a high lift cam and a low lift cam ?

[99-LS1-SS]

The amount that the valve opens to let air and gas in and exhaust out.

Maybe this explanation will help.

Lift
Lift refers to maximum valve lift. This is how much the valve is "lifted" off its seat at the cam lobe's highest point. The intake and exhaust valves need to be open to let air/fuel in and exhaust out of the cylinders. Generally, opening the valves quicker and further will increase engine output. Increasing valve lift, without increasing duration, can yield more power without much change to the nature of the power curve. However, an increase in valve lift almost always is accompanied by an increase in duration. This is because ramps are limited in their shape which is directly related to the type of lifters being used, such as flat or roller.


Duration
Duration is the angle in crankshaft degrees that the valve stays off its seat during the lifting cycle of the cam lobe. Increasing duration keeps the valve open longer, and can increase high-rpm power. Doing so increases the RPM range that the engine produces power. By increasing duration without a change in lobe separation angle will result in increased valve overlap.

[GEE8GEETEE]

How do you know which you would need ?

[99-LS1-SS]

Which what? Are you asking if you need a higher lift cam or a lower lift cam? If so, typically a the higher the lift the more power you'll make. Duration needs to be taken into account too. If you want to know what lift you should get then you need to determine what you want out of your car.
I'm sure Charlie and some of the site vendors can give you exact numbers or at least a range.

[GRRRR8]

Need is based on performance goals for your application. Most Stage 1 cams are enough for a DD. Stage IIs are also OK for a DD, just a bit more aggressive.

[GEE8GEETEE]

So if i want just cam, LT headers, cai, exhaust and a tune then i guess i would want the higher lift cam ? Especially since the low and high are the same price?

[GRRRR8]

Correct. They are all higher then stock and you need to figure out if you are keeping DOD.

[p71]

If it is not to technical think about it this way... higher lift cams are the equivalent of a low lift cam with higher ratio rockers... valves open faster and farther.

[Ed Curtis]

Camshaft Terminology (http://www.hardcorels1.com/vbulletin/showthread.php?t=111)

Camshaft Tutorial (http://www.hardcorels1.com/vbulletin/showthread.php?t=136)

Read this stuff and see what's what....

Also... don't get all blind sided with the duration specs. Most camshaft specs you'll see posted up will only include one duration point. More times than not, it's at .050" tappet lift. That's why you see cams called out as a "224* grind" and not much more. The problem with that is the 224* number is only a singular point of duration and there are many more points of duration in a lobe. I believe at last count I have over 30 camshaft lobes with a 224* duration spec at .050" tappet lift yet each one is different than the other. So... when you hear "run a 224* camshaft" ... I wouldn't listen too carefully to that guy because he hasn't really got a grasp on lobe design. ;)

Ed

[GEE8GEETEE]

OK thanks alot everyone. I feel much more informed now. :) Not sure about the DOD yet. It has it's pros and cons which i'm still weighing. More than likely i'll end up keeping it since i don't really plan on doing more than mentioned above. Of course, my mileage sucks anyways and i mostly do city driving, so maybe i'll get rid of DOD....ha ha Guess i have some thinking to do.

[TheTugBoat]

pretty good sticky going right here.