Single Overhead Camshaft V8s

[TehMac]

Have two camshafts, one for each side of the block...

right?

 

[BassBomb]

believe so

 

[Fenixgoon]

edit: woops...

 

[EightySix Four]

Yes...

 

[JulesMaximus]

Eyefirmative

 

[TehMac]

what drives both camshafts?

 

[JulesMaximus]

what drives both camshafts?

Belt or a chain...depends on the engine.

 

[Bignate603]

what drives both camshafts?

The timing chain (or belt but I hate timing belts) runs up from the crankshaft to each cam.

Link if image doesn't work

 

[TehMac]

So what powers the crankshaft if its run by the pistons, which in turn depend on the camshaft to operate the valves?

I'm sorry for sounding dense, I've been genuinely wondering about this for a while.

 

[EightySix Four]

So what powers the crankshaft if its run by the pistons, which in turn depend on the camshaft to operate the valves?

I'm sorry for sounding dense, I've been genuinely wondering about this for a while.

The starter motor initially turns the motor over and starts the process. This draws air and fuel into the cylinder which ignite. Pushing the piston down, turning the crank shaft, turning the cam, which allows air and fuel into the cylinder, which ignites... You get the idea.

Some direct injected engines use a crank sensor and inject a little fuel into whichever cylinder is in the right position and ignite it, instead of using a starter motor.

You're lost because you can't figure out where the energy in the equation comes from, you're forgetting the fuel/air

 

[JulesMaximus]

So what powers the crankshaft if its run by the pistons, which in turn depend on the camshaft to operate the valves?

I'm sorry for sounding dense, I've been genuinely wondering about this for a while.

The pistons are driven up and down by the firing of the spark plug igniting fuel/air mixture in the combustion chamber. The pistons turn the crankshaft which turns the cams which open and close the valves letting fuel/air into the combustion chamber and spent exhaust gasses out after combustion. It is a very precise process and timing is of the utmost importance in this process.

 

[EightySix Four]

The pistons are driven up and down by the firing of the spark plug igniting fuel/air mixture in the combustion chamber. The pistons turn the crankshaft which turns the cams which open and close the valves letting fuel/air into the combustion chamber and spent exhaust gasses out after combustion.

I love your new avatar, serves as an excellent warning for noobs who don't know you.

 

[JulesMaximus]

http://www.youtube.com/watch?v=FfTX88Sv4I8

 

[JulesMaximus]

I love your new avatar, serves as an excellent warning for noobs who don't know you.

It's best not to over think these things...you might hurt yourself.

 

[BW86]

http://www.youtube.com/watch?v=FfTX88Sv4I8

I used to have this as a screensaver

 

[TehMac]

It's best not to over think these things...you might hurt yourself.

Is that the democrat's new campaign slogan?

 

[JulesMaximus]

Is that the democrat's new campaign slogan?

No, that's my new slogan for anyone who gives me shit about my avatar.

BTW-I'm actually registered as republican.

 

[TehMac]

BTW-I'm actually registered as republican.

tisn't possible


NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOooooooooooooooooOOOOOOO!



Anyway...back to my thread.

 

[BlackTigers]

tisn't possible


NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOooooooooooooooooOOOOOOO!



Anyway...back to my thread.

combustion moves the pistons, which spins the crank, which (through a belt) rotates the cams, which operate the valves.

rinse and repeat.

 

[compman25]

 

[TehMac]

combustion moves the pistons, which spins the crank, which (through a belt) rotates the cams, which operate the valves.

rinse and repeat.

Yes, but if the valves aren't operating when the car is turned off how can the gas/air be released into the combustion chamber?

I guess that's what the battery is for? But if the battery turns the engine, again, how does the proper ratio of gas/air enter the combustion chamber to move the pistons?

 

[EightySix Four]

Yes, but if the valves aren't operating when the car is turned off how can the gas/air be released into the combustion chamber?

I guess that's what the battery is for? But if the battery turns the engine, again, how does the proper ratio of gas/air enter the combustion chamber to move the pistons?

Start up AFR is not incredibly important except in the cold. When you turn the key the battery sends power to turn the starter motor over. As the cylinder goes down, it draws air and fuel into the cylinder and the spark plug tries to ignite it. Once it ignites, it's should power itself.

This is also how you "flood" a car, when it keeps trying to start and keeps adding gas, but doesn't start, it'll eventually end up with tons of fuel in each cylinder and make it very hard to start.

 

[BlackTigers]

Yes, but if the valves aren't operating when the car is turned off how can the gas/air be released into the combustion chamber?

I guess that's what the battery is for? But if the battery turns the engine, again, how does the proper ratio of gas/air enter the combustion chamber to move the pistons?

The starter (on my car) engages the fly wheel.

When the starter cranks, it spins the flywheel. Which yanks the crank around (the car "turning over"), and this in turn drives the cam shafts (lifting the valves), which let the fuel enter the engine, and the CPS signals the coils to start sparking, creating the combustion needed to start the process.

 

[EightySix Four]

I'm actually a bit confused as to what part you are getting hung up on. When the electric starter motor engages, it turns the whole motor over, pistons, crank, cams, etc. Just like if it was operating normally.

 

[Bignate603]

Yes, but if the valves aren't operating when the car is turned off how can the gas/air be released into the combustion chamber?

I guess that's what the battery is for? But if the battery turns the engine, again, how does the proper ratio of gas/air enter the combustion chamber to move the pistons?

When the car is started the starter motor (an electric motor powered off the battery) spins the flywheel. The flywheel is attached onto the crankshaft so it rotates too, which causes the chain/belt that turns the camshaft to begin moving. Because that is moving it actuates the valves.

Basically the whole system (valves, camshaft, timing chain/belt, crankshaft and flywheel) is all hooked together. When the starter turns the flywheel it all turns. Once it spins up and it's moving air through the engine the car can begin to give it fuel and ignite it.

On cars with carburetors I would assume that its giving it fuel as soon as air starts getting sucked into the engine but on modern fuel injected cars I'm not sure if the car delays providing fuel until the engine reaches a certain rpm. Does anyone here know?