BORN2LOSE

I know what one looks like and where it is at in the engine but I don't understand how it works or how it makes more power with more duration etc. And what kind of maint do you have to do after installing an aftermarket cam? This may be something I want to add down the road. I have a few boltons with an A4. Just wondering if its possible to get to 400HP and pass emmissions with an auto for under $1000 installed without doing heads or getting a huge cam. Thanks in advance.

Raise

iTrader: (31)

a cam is the brain of ur engine. it controls the opening and closing of the valves. it dictates when your valves open and close and how long they stay open. in turn, this indicates how much air/fuel u are bringing into the engine. therefore, the more air/fuel your are bringing into the engine, the more power u will make. but, the cam itself is controlled by the crank via the timing chain. example:
tr224 specs are: 224/224 .563/.563 114lsa
224 is duration..this is how long each valve stays open....this is measured in crankshaft degrees. .563" is lift of the cam. it actually measures the distance the valve opens from its seat.....measured in thousands of an inch. lift is generated by the cam converting rotational motion to linear motion via the lifters and pushrods. the lsa (lobe separation) measures the distance between the intake centerline and the exhaust centerline(imaginary line drawn from the center of the base circle to the center of the nose of the lobe). basically look down the end of the cam...pretend theres a circle drawn around the end of the cam with a radius of the center of the base circle to the nose of the lobe. the distance between where the intake and exhaust lobe centerlines(nose) touch the perimeter of that circle is the lsa...measured in camshaft degrees.

777

iTrader: (21)

he hit the nail on the head...for what you want i suggest his "example cam" the tr224...it should get you around 400rwhp and have stock like driveability and would be the most likely canditate out of any to reach 400 to be able to pass emisions

Raise

iTrader: (31)

and the tr224 is a low maintenance cam. change your valvesprings, retainers, and hardened pushrods and be done with it. depending on what springs u go with, u might wanna check them at 15-20k miles. people have seen 400 to the wheels with this cam on stock heads thru a 6-speed car. autos generally lose more hp thru the drivetrain than m6 cars.

Adrenaline_Z

"the distance between the intake and exhaust lobe is the lsa...also measured in crankshaft degrees."

Actually, LSA is measured in camshaft degrees, not crank degrees.

If you think about it, the ascending ramp of the lobe @ 0.006" lift to the
descending ramp of the lobe @ 0.006" can be 250 degrees.

If LSA was measured in crank degrees, the lobe centers would be no further
apart than the width of a cam lobe... nearly half the distance.

All else looks good.

There are some wicked articles on engine tuning which can dive deeper
into camshaft technology. Just play around in your serach engines and
you'll find a mountain of tech.

Raise

iTrader: (31)

now heres a lil explanation of how changing the specs affects power:
duration - the longer the duration, the more air u will be able to fill the cylinder with at higher rpms, when there is less time to do so. but down low, with the intake valve staying open longer, there is less pressure in the intake manifold than in the cylinder, so the piston forces air back up into the intake manifold. this is commonly referred to as "reversion." now, the shorter the duration, the more low to mid range power u will make. at lower rpms, when there is more time to fill the cylinder, the short duration cam allows quicker opening and closing of the valves. but up top, because the quick opening and closing of the valves cannot adequately fill the cylinders, so u will suffer at higher rpms. so u really wanna decide what u wanna do with the car before picking a cam application. short duration=good torque. long duration=good high end power
LSA - the tighter(smaller) the lobe separation, the more valve overlap u will experience. (overlap=time in camshaft degrees that both the intake and exhaust valve are open) this will give the cam good torque while narrowing the power band. a larger lsa will open up the power band. this sounds good, because u might see a nice flat power curve, but the car will be a lil lazy gettin up there....as opposed to a drastic climb.
i must say tho, these days i have seen **** proven and disproven. it seems all cars will react differently than others. some cams that shouldnt make torque (by the books) are makin killer low end power. some small cams are pullin hard all the way to the top of the hill. crazy ****
this is merely an overview of the specs of a cam and how they affect performance. there are tons of lil factors that determine how each and every particular application will perform, but at least now u should have a good general idea of what a cam's purpose is.

Raise

iTrader: (31)

my bad, youre right. i knew better. brainfart = typo =
thats why i told him to look down the cam to check out the angle.....of course its camshaft degrees

5POINT7

Darn good info here.

Great thread!

Raise

iTrader: (31)

DONAIMIAN

iTrader: (18)

www.howstuffworks.com
best website ever, next to LS1tech ofcourse

TAQuickness

iTrader: (28)

You beat me to it.

BORN2LOSE

Thanks for the info guys!

ZR2877

Great information. My friend that's getting stuff installed on his car ask me where he can find info about what does what and I couldn't tell him where to go to find it now I can.