Cam question for the mechanically ignorant...
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,038
Likes: 3
From: Charlotte North Carolina
Cam question for the mechanically ignorant...
I know next to nothing about engine mechanics but I am attempting to learn what I can by reading posts. My understanding is that the cam shaft is the spinning rod connected to the pistons that causes them to go up and down. Is this right? If so, how does a different cam increase performance / hp, etc...?
I hear of a many people doing this mod, but I don't get it. Will someone please kindly enlighten me? I am curious. Thanks in advance for your responses.
I hear of a many people doing this mod, but I don't get it. Will someone please kindly enlighten me? I am curious. Thanks in advance for your responses.
Le Mans Master
Joined: Aug 2000
Posts: 8,762
Likes: 2
From: Murphy TX
Close 
The crankshaft is the spinning rod of which you speak
The cam, of which the LS1/6/2/7 have only one, is a rod above the crank that actuates the valves. Our engines have what are called pushrods that the crank pushes up and down, those pushrods run up to what are called rocker arms which open and close the valves.
http://auto.howstuffworks.com/engine.htm is a good start.
Also
http://auto.howstuffworks.com/camshaft.htm is a good one too, although specifically a pushrod engine is what we have: http://auto.howstuffworks.com/camshaft5.htm
Hope this helps! Prepare to have your brain filled!
The crankshaft is the spinning rod of which you speak
The cam, of which the LS1/6/2/7 have only one, is a rod above the crank that actuates the valves. Our engines have what are called pushrods that the crank pushes up and down, those pushrods run up to what are called rocker arms which open and close the valves.
http://auto.howstuffworks.com/engine.htm is a good start.
Also
http://auto.howstuffworks.com/camshaft.htm is a good one too, although specifically a pushrod engine is what we have: http://auto.howstuffworks.com/camshaft5.htm
Hope this helps! Prepare to have your brain filled!
Melting Slicks
Joined: Dec 2004
Posts: 2,322
Likes: 2
From: New York NY
Cruise-In VI Veteran
St. Jude Donor '05
The camshaft opens and closes the intake and exhaust valves that let the air/fuel mixture in and out of each piston for combustion. Our ls1 engines are pushrod engines meaning that there is one camshaft that opens and closes all valves. There are 16 valves --> 1 intake valve and 1 exhaust valve per each of the 8 pistons. Here is a writeup that will tell you a lot you want to know about cam specs.
http://ls1howto.com/index.php?article=23
If you want to know the physics of how a cam operates check this out:
http://auto.howstuffworks.com/camshaft.htm
oh apparently some one beat me to it!
dont forget this one too
http://www.ls2.com/forums/showthread...threadid=19550
http://ls1howto.com/index.php?article=23
If you want to know the physics of how a cam operates check this out:
http://auto.howstuffworks.com/camshaft.htm
oh apparently some one beat me to it!
dont forget this one too
http://www.ls2.com/forums/showthread...threadid=19550
Last edited by Icemanskis; May 5, 2005 at 07:43 PM.
Le Mans Master
Joined: Aug 2000
Posts: 8,762
Likes: 2
From: Murphy TX
Now a different crank can increase HP/TQ too because the longer the pistons travel (the stroke) effectively increases the displacement of the engine, which is a function of stroke and bore (diameter of cyllinders).
Le Mans Master
Joined: Dec 2003
Posts: 7,506
Likes: 0
From: Hillsborough NJ
Originally Posted by yellow01
Close
The crankshaft is the spinning rod of which you speak
The cam, of which the LS1/6/2/7 have only one, is a rod above the crank that actuates the valves. Our engines have what are called pushrods that the crank pushes up and down, those pushrods run up to what are called rocker arms which open and close the valves.
The crankshaft is the spinning rod of which you speak
The cam, of which the LS1/6/2/7 have only one, is a rod above the crank that actuates the valves. Our engines have what are called pushrods that the crank pushes up and down, those pushrods run up to what are called rocker arms which open and close the valves.
And the shin bone's connected to the thigh bone, the thigh bone's connected to the hip bone...
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,038
Likes: 3
From: Charlotte North Carolina
These mods seems like they would be fairly easy to incorporate into the initial engine build with little to no additional cost to manufacture. Why doesn't Chevy give us a better cam from the factory? My uneducated guess is that it would negatively impact fuel consumption numbers. Am I right? Are there other reasons?
Team Owner
Joined: Nov 1999
Posts: 26,679
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From: This vette goes to 11 Milford MA
St. Jude Donor '03-'05
Originally Posted by Prosecutor
These mods seems like they would be fairly easy to incorporate into the initial engine build with little to no additional cost to manufacture. Why doesn't Chevy give us a better cam from the factory? My uneducated guess is that it would negatively impact fuel consumption numbers. Am I right? Are there other reasons?
EPA regs on emissions, fuel consumption as well as idle quality.
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Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,038
Likes: 3
From: Charlotte North Carolina
Originally Posted by Fastguy
EPA regs on emissions, fuel consumption as well as idle quality.
Thanks guys, I learned a lot. That howstuffworks link is great. It even has animations.
Advanced
Joined: Apr 2005
Posts: 78
Likes: 0
It's not only the darn hippies fault. Most people want to buy a car that they can hardly feel is running at a stop - they don't want to feel the loppy idle of a hot cam and have to keep the revs up to keep it from dying. There are others of us that like the loppy idles (
)
And if they put in a hot cam then people would just want to take it out and put in a hotter cam. They would call the stock cam junk and upgrade...
I know with the L98 engines they went through a lot of cams, some slow ugly ones (peanut cam) and some more aggressive. I don't know if there are different ones for the LS1 though.
)And if they put in a hot cam then people would just want to take it out and put in a hotter cam. They would call the stock cam junk and upgrade...
I know with the L98 engines they went through a lot of cams, some slow ugly ones (peanut cam) and some more aggressive. I don't know if there are different ones for the LS1 though.
Le Mans Master
Joined: Aug 2000
Posts: 8,762
Likes: 2
From: Murphy TX
Cams also affect where in the RPM range the engine makes it's power.
For a primarily street car, it is desirable to have as much power as possible under the entire curve and high torque down low, where you typically drive it.
If you live life between 4 and 6k RPM a different cam may be advantageous, but most don't.
The stock engine is pretty impressive. There aren't too many cars I know of that get 32MPG on the way to the racetrack that can then run 2 days full out on a track and then get 32MPG on the way home. The gen III really is an amazing engineering feat.
For a primarily street car, it is desirable to have as much power as possible under the entire curve and high torque down low, where you typically drive it.
If you live life between 4 and 6k RPM a different cam may be advantageous, but most don't.
The stock engine is pretty impressive. There aren't too many cars I know of that get 32MPG on the way to the racetrack that can then run 2 days full out on a track and then get 32MPG on the way home. The gen III really is an amazing engineering feat.
Safety Car
Joined: Mar 2002
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Cruise-In V Veteran
St. Jude Donor '09
Racer
Joined: Aug 2001
Posts: 469
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From: Pasadena MD
Originally Posted by Prosecutor
So its the damned hippies ruining all of the fun huh?
Thanks guys, I learned a lot. That howstuffworks link is great. It even has animations.
Thanks guys, I learned a lot. That howstuffworks link is great. It even has animations.
NOT ALL US "DAMNED HIPPIES" ARE TREE HUGGERS
(get it?)
Drifting
Joined: Jul 2002
Posts: 1,613
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From: Spring Tx
OMG Where are the real experts? "Our engines have what are called pushrods that the crank pushes up and down, " My crank does not have any push rods connected to it, it allows my pistons to move up and down,it turns my oil pump,and turns my cam, on the other hand the cam moves the lifters up and down which in turn move the pushrods which move the rocker arms which then opens the valves which are held open by valve springs that are capped by retainers and held in place by two piece locks...The valve stems pass through the valve spring seat a seal and a bronze guide as they do their little power dance.Tomorrow class, the subject will be " Where babies come from" and our guest lecturer will be Professor Ima Stork
Melting Slicks
Joined: Dec 2003
Posts: 2,857
Likes: 2
From: pawleys island sc
Originally Posted by yellow01
Oh crap I just realized my typo!! 
I said the crank pushes the pushrods
Obviously the cam does
sorry...
I said the crank pushes the pushrods Obviously the cam does
sorry...
Le Mans Master
Joined: Aug 2000
Posts: 8,762
Likes: 2
From: Murphy TX
Originally Posted by lost
Please note I did not mention the posters name or in any way try to embarrass him.I just have a perverted sense of humor and when these situations present themselves, I cannot control myself.....
Safety Car
Joined: Jul 2001
Posts: 4,661
Likes: 67
From: Ocean Springs MS
Originally Posted by Prosecutor
These mods seems like they would be fairly easy to incorporate into the initial engine build with little to no additional cost to manufacture. Why doesn't Chevy give us a better cam from the factory? My uneducated guess is that it would negatively impact fuel consumption numbers. Am I right? Are there other reasons?