Honda Car Forum

what's the different and what they mean? which one is better?

single over head camdual over head cam

SOHC means Single Over Head Cam. The camshaft is what activates the valves in an engine's cylinder head so that it can draw in and expel air. Usually a DOHC (Dual Over Head Cam, 2 per cylinder head), will result in better airflow and thus more power because more valves can be used.As far as which is better, it really depends on your application and what kind of power or economy you're looking for.Check out HowStuffWorks for some more info:http://auto.howstuffworks.com/camshaft1.htm

It's about how many cam shafts there are that regulate valve opening.SOHC is a single overhead cam. This means one cam shaft regulates both the opening and closing of both the intake and the exhaust valves.A DOHC is a double overhead cam. Typically one cam shaft is used to regulate the opening of the valves for the cylinders. A different cam shaft is used to regulate the opening of the exhaust valves.Since the SOHC has only one cam shaft, you can not vary when the intake and exhaust valves can open during the engine cycle.With a DOHC there is a way to change when in the combustion cycle the intake and exhaust valves open. Typically called Variable valve timing (VVTi in Toyotas, VTEC - Variable Valve Timing and Lift Electronic Control in Hondas)A DOHC will give you more options on how you want to control the opening and closing of the valves. The control of when to open valves and close them can allow for an optimum performance in both power as well as a reduction in NOx emissions. (Which by the way is one of the real reasons for it's development) The VVTi/VTECH engines can do without emission devices such as EGR valves and NOx emissions can simply be reduced with proper valve timing.

1 cam. Dual is always better.

The difference is one cam. !!The DOHC is better but more expensive to repair.

The difference is the number of overhead cams. And I belive DOHC will last longer.

SOHC = single overhead cam, DOHC = dual over head cam.single is a single cam above the crankshaft, usually with 2 valves, the dual is a cam over each cylinder head, with 4 valves, making less work, and better performance.

SOHC is single overhead cam,DOHC is double overhead cam ,often used with 4 or more valves per cylinder.

SOHC means Single Over Head Cam, DOHC means Dual Over Head Cam. Multiple camshafts means that it is easier for the manufacturer to use more valves per cylinder (although this can be done with SOHC - just look at the old Triumph Dolomite engine.) The other main benefit is that it allows the valves to be placed with the stems angled away from each other to a much greater degree (meaning that the valve heads are angled towards each other) - this improves flow through the combustion chamber from the intake valve to the exhaust valve, which gives both improved efficiency and more horsepower, especially at high rpm - which is why it is considered more important on small engines, and in sports cars.