Hi, I was wondering what does DOHC(double overhead camshaft) looks like? what do I mean is that DOHC says it...Double camshaft. But does it mean that you have one camshaft for the intake valves and one camshaft for the exhaust valves? In that case SOHC would mean that you have one camshaft operating the intake and exhaust valves? And what does happen when you have a V type engine (V6, V8)? This really mix me up. Hope you can help.

Thanks

 

3 common setups, cam in block, SOHC and DOHC. Cam in block is like the typical old school V8 and most American V8s up until the mid 90's or so, and the current GM LS engine family. 1 single camshaft in the center of a V engine(or off to the side in an inline engine) where all the lobes for all intake and exhaust valves are on the same cam and lifters ride on the cam and move pushrods. A SOHC puts the camshaft in the head(inline) or heads(V or opposed) and has lobes for all the intake and exhaust valves for that particular head(in the case of a V engine that one side or bank of the engine). A DOHC is like SOHC except one cam operates the intake valves and one cam operates the exhaust valves for that one particular bank. So in a V8 for instance a cam in block has 1 cam in the middle, a SOHC has 1 cam in each cylinder head(2 total) and a DOHC has 2 cams in each cylinder head(4 total).

 

And in the case of the Stang 4.6 engine, DOHC also adds more valves to the engine (2 intake 2 exhaust)& that's where the extra performance of a DOHC is really coming from.

 

I was going to draw an MS paint diagram but I got lazy about 5 mins in [8D]. Basically a pushrod motor has the cam in the middle of the block (roughly) while an OHC engine has the cam(s) sitting on top of the motor so no pushrods there.

Basically what these guys have said but in much simpler terms.

 

even simpler DOHC means there is 2 cams per head and SOHC means 1 cam per head

 

Some DOHC engines have 5 valves, like Porsches for instance. And the new 4.6L in the 05-up Mustang GT's is a SOHC with 3 valves.

http://en.wikipedia.org/wiki/Valvetrain

There are sections where you select OHC and pushrod, and even camless, and see what they look like.

http://auto.howstuffworks.com/camshaft1.htm

And that has better pictures and some animated images.