please help with cam issue (z28pete?)
Ninja Administrator
Joined: Jun 2007
Posts: 6,172
From: Potato
RE: please help with cam issue (z28pete?)
ORIGINAL: 95slvrZ28
Unfortunatly I don't have time to type up a whole description of what different durations do for you. Cliff Notes version says the higher (longer) duration you have, the longer the valve (whether that be intake or exhaust) is open. A shorter duration will produce more low end torque and a higher duration will produce more top end power but the heads must support the extended flow. The detriments with going with a very long duration is you start to lose engine idle vaccume to operate your power brakes etc. and you start to lose idle quality (this combined with lobe separation is what determines the idle). As you increase duration of either intake or exhaust you increase the valve overlap time. This is the time that both the intake and exhaust valves are open, it allows for more flow at higher RPM, but it hurts idle.
Here's a good guide to picking our your camshaft. The guy that wrote the guide works at a shop that is local to me, got a Mechanical Engineering degree from the University of Colorado at Boulder (w00t!!) and gets some amazing numbers out of cars (as you can see if you browse through the main page). http://www.dragonrace.com/
(go to Tech and FAQ on the left side of the page, there's a link to the camshaft protion, it's all good reading)
And Here's a general guide that describes in not too much detail the different aspects of a cam.
Unfortunatly I don't have time to type up a whole description of what different durations do for you. Cliff Notes version says the higher (longer) duration you have, the longer the valve (whether that be intake or exhaust) is open. A shorter duration will produce more low end torque and a higher duration will produce more top end power but the heads must support the extended flow. The detriments with going with a very long duration is you start to lose engine idle vaccume to operate your power brakes etc. and you start to lose idle quality (this combined with lobe separation is what determines the idle). As you increase duration of either intake or exhaust you increase the valve overlap time. This is the time that both the intake and exhaust valves are open, it allows for more flow at higher RPM, but it hurts idle.
Here's a good guide to picking our your camshaft. The guy that wrote the guide works at a shop that is local to me, got a Mechanical Engineering degree from the University of Colorado at Boulder (w00t!!) and gets some amazing numbers out of cars (as you can see if you browse through the main page). http://www.dragonrace.com/
(go to Tech and FAQ on the left side of the page, there's a link to the camshaft protion, it's all good reading)
And Here's a general guide that describes in not too much detail the different aspects of a cam.
Overdrive Member
Joined: Aug 2006
Posts: 4,496
From: Boulder, CO
RE: please help with cam issue (z28pete?)
Thanks Spec, in my defense I did say that it wasn't a complete guide. 
Cam wear was more of a consideration back in the mechanical tappet sort of cams, any hydraulic roller assembly doesn't wear in the cam like they used to. I would be willing to say that it's probably safe, although maybe not the best idea to install a used cam.
Choosing a cam is hard business, if anyone has checked out the Dragon Race guide, as it says at the very beginning "If you put him and 4 of the best engine builders in the world together in one room and you asked them to design a cam for a certain application you would get 5 different answers."
Cam wear was more of a consideration back in the mechanical tappet sort of cams, any hydraulic roller assembly doesn't wear in the cam like they used to. I would be willing to say that it's probably safe, although maybe not the best idea to install a used cam.
Choosing a cam is hard business, if anyone has checked out the Dragon Race guide, as it says at the very beginning "If you put him and 4 of the best engine builders in the world together in one room and you asked them to design a cam for a certain application you would get 5 different answers."
NOOO they be stealin' my bucket
Joined: May 2007
Posts: 2,200
From: Fort Brag NC (no longer in iraq)
ROTM Winner's Club
RE: please help with cam issue (z28pete?)
ORIGINAL: SpecterGT260
....... ur sarcasm has earned u a new memeber tag
MWAHAHAHAHAHA
eh.... maybe not right now...... forum is acting up
....... ur sarcasm has earned u a new memeber tag
MWAHAHAHAHAHA
eh.... maybe not right now...... forum is acting up
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