SOHC VS DOHC

Differences DOHC VS SOHC

DOHC stands for Double Overhead Camshaft (as an alternative to the SOHC engine type). Layout engine uses two back (camshaft as) on top of the engine block. It also means that the engines are DOHC V 4 camshafts because there are two blocks that make it easier for the machine manufacturer implements 4 valves per cylinder. Most also brings propeller DOHC engine (RPM) is higher.
Better layout optimizes valve setup that maximizes engine performance as well. But its shortcomings, the weight will increase, more expensive, and more complicated. Also more parts to play two back.
The main reason to use a DOHC valve to add more on each cylinder. (But) if SOHC allows the use of 4 valves per cylinder (as in MX or Thundy 250), the DOHC is no longer everything. Especially with a heavier weight.


In short, SOHC 16 valve has better torque at low rpm because it is lighter (rotating machine) and vice versa DOHC engine produces more torque due to the weight lower. But in at high speed, 16 valve DOHC engine torque will be better. That's the trade-offs. When the spigot amount equal, SOHC has better low-end torque while DOHC has better top-end power is higher.
Another advantage, easier to apply tenologi DOHC variable valve timing (VVT) and ditune-up easier. If you intend to use a back-profile racing on the DOHC, lobe profiles can be optimized for easier fiddling add modifiers in a separate state.
Why need more valve? Why you do not make each one suction valve and discard it? Of course not. Larger valve would be heavier and would be very difficult to control at high engine speed. Per valve must be rigid, which means also the extra energy needed to withstand the pressure (motion) valve. Useless, is not it!
Also at low engine propeller, the large valve suction velocity becomes lower. Simply this: the power of pressure on a hole that big is definitely smaller than the holes smaller. Because the suction velocity decreases, low torque and engine movement also weakened.
Although two smaller valve would weigh 1 large valve, and with the addition of the trigger valve (rocker arm) and by which means a little heavier, but all that means nothing compared to decreasing the burden on the process of opening and closing the valve. So, more valves per cylinder is more profitable?
Let's compare a Nissan VG30E versus VG30DE. Both 3.000cc with electronic fuel injection, but that the 2 valve SOHC and DOHC 4 valve latter per cylinder. Consider the diagrams below. Look at the same RPM at low speed, but 2 valves per cylinder has reached its peak and had to change gears, while the twincam 4 valve per cylinder continues to add energy at its peak powerband. Powerband (power distribution) is also longer. But remember, this graph to determine the different 2-valve and 4-valves, not to compare the SOHC vs DOHC.
Show SOHC

In conclusion, SOHC has better torque down lap, while the opposite DOHC (peak power and energy distribution of the maximum length of time). 4 valves per cylinder better than 2 valves per cylinder, 4 valves either the SOHC or DOHC dipanceng on.

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