What's the different between SOHC and DOHC?

Question

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

Answer 1

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

Answer 2

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.

Answer 3

The dohc is Double over Head cam sohc is single the dohc has a cam shaft over the intake valves and one over exhaust valves single is 1 camshaft running all valves on 1 head with 1 cam. Sohc is used in lower cost engine , less parts , less power. double is the standard now as most engines ar 4 valves per cylinder and having a cam over each bank of valves has less mechanical drag while working, sohc usually has a rocker arm Thai is in the center of head and the cam works the arms to move the valves

Answer 4

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.

Answer 5

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.

Answer 6

VTEC - Valve Timing(and carry ) Electronically controlled. I-vtec is the same element, yet with VTC. additionally many times happening as Variable Cam phasing. i don't be attentive to why im going to take a seat down right here and positively form this out, yet luckily I form exceedingly speedy.. With a VTEC motor, in any respect cases of acceleration 4 valves artwork consistent with cylinder. With an I-VTEC motor, below VTEC the two Exhaust valves artwork and purely a million intake valve opens. This reasons extra suction from the only intake valve being open which additionally reasons all the air that gets sucked in to be sucked in with a spirial like action. The gasoline is then allotted during the combustion chamber extra frivolously. starting to be extra useful low end torque useful properties. This one intake valve working action is many times happening as VTC or Variable Cam Phasing. whilst VTEC is crossed over to the different intake valve opens and all 4 valve artwork. i've got understood that the older VTEC only has the intense-carry cam switchover, and the extra cutting-edge i-VTEC provides continuously variable cam phasing. Plus, the cam changeover RPM can variety looking on throttle place and whatnot; i'm not sure if that's only on i-VTEC or if it become additionally on the older variations of VTEC too. at the same time as the EP3's A3 motor would not have a intense-carry cam for intense RPM's (the 2200 rpm swap between 12 and sixteen valves is for various motives), it does enhance/retard the cams' overlap as mandatory during the RPM variety.

Answer 7

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

Answer 8

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

Answer 9

The difference is one cam. !!

The DOHC is better but more expensive to repair.

Answer 10

1 cam. Dual is always better.