Honda Car Forum

I know what it means, i just want to know what it's for and how it helps the engine work better.

On a dual over head cam the cams are right in the head and have a direct drive to the valves this gives it more dependability and allows the vehicle to perform much better than a conventional camshaft.

Dual Overhead Cams

dual over head cam

Dual overhead cams allows the engine to obtain higher RPMs and thus higher horsepower compared to an overhead valve engine with the same displacement and number of cylinders. Overhead valve (pushrod) engines are limited because the the pushrods will break if revved too high. A dual overhead cam engine allows for more valves as opposed to a single overhead cam engine and thus also produces more power. Having more valves allows an engine to "breath" better. There is usually one cam for intake valves, and the other cam for exhaust valves.

Bad part, screw your cam; screw your block....

Duel Over Head Camshaft,the reason an engine works a lot better is the engineers can design the intake duration and exhaust duration differently on separate cams than if they on one single camshaft,just by off setting the cam drive on each camshaft they can achieve more horse power.If you think this is technical try HCVVT.Hydraulically Controlled Variable Valve Timing.Does the same thing only a lot better and it's computer controlled.

instead of having a single camshaft doing all the opening and closing of the intake and exhaust valves. A Dual Overhead Camshaft is cheaper to tune because in a SOHC, you need to grind a whole new camshaft to change the power/economy/emissions. In a DOHC, all you gotta do is change to timing on the exhaust camshaft if you wanna change power/economy/emissions settings. Also, 2 camshafts are smaller and lighter than 1 big camshaft. so it's lighter because it uses less metal, and it's less work to turn two little camshafts vs. a big heavy camshaft.My Chrysler 300M is a SOHC but it's got 24 valves, so it still breathes but it's got less parts than a DOHC so it's cheaper to make. And nobody is gonna be modifying the breathing on a Chrysler.The other big thing is the sparkplug. it sits in the middle of the DOHC so it fires in the center. The SOHC has to fire the plug from an angle.

it work with both camshaft so the engine fire quicker when you start the car. most honda, toyota, and nissan has it. a very few american, german car have it.

D = Dual. meaning it has separate mechanicals controlling intake(1) and exhaust(2) valves, hence, "dual"OH = overhead. meaning the mechanicals controlling the valves are "over" the engine head. they are located closer to the actual parts they're controlling. hence, less distance the force has to travel through the mechanicals.C = Cams. A part that controls the opening and closing of the valvesIn another words, DOHC = "There are two parts that control the valves (cams) located right over the head of my engine."DOHC doesn't always necessarily mean it's better than other designs; i.e. OHV (overhead valve: cam is located farther away from the valves that it controls) or SOHC (single: single cam does both duties, intake and exhaust)and it doesn't always mean it has a "variabale" (another can of worms) technology. it all depends on the application and individual design. But when all else are equal, DOHC design provides more flexible/efficient way for engine to breathe more.