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SOHC Vs DOHC: What’s The Difference?

If you’ve ever been in the process of buying a new vehicle or even just casually browsing spec sheets, you’d probably come across terms like SOHC and DOHC. Now, they might’ve mentioned that they relate to the camshaft, but what is the camshaft? And how does a SOHC or DOHC differ your driving experience? This article will help clear all that out!

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What is a Camshaft and its purpose?

The camshaft is a rotating rod that moves against a piece of machinery, turning rotational motion to reciprocal motion. It is responsible for opening the valves. That means the camshaft is accountable for how much fuel goes into the engine for combustion and how much fuel from that combustion is released as energy. Each camshaft has two valves, one responsible for intake and one responsible for exhaust.


Now that we know what a camshaft is and what role it plays, let’s find out about the SOHC and DOHC: –

  • SOHC means Single Overhaul Camshaft, and DOHC means Dual Overhaul Camshaft.
  • In SOHC, there is a single camshaft installed in the cylinder head of the engine, where one valve is responsible for intake, and the other valve is responsible for exhaust.
  • In DOHC, there are dual camshafts in the engine, meaning two intake valves and two exhaust valves owing to 4-valve. Most engines nowadays run on DOHC.

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SOHC Vs DOHC: Which is better?

PerformanceFuel-EfficiencyRunning and Repair CostEfficiency and Smoothness
SOHCLesser performance due to 2 valvesLess efficient due to one intake and exit valve.Due to lesser moving costs, its cheaperIt is less smooth and vibrates a lot more.
DOHCDue to their being 4 – valves per cylinder, more horsepower is produced owing to higher performance.Two intake and exhaust valves ensure higher efficiency leading to lower fuel consumption.More valves mean more moving parts, which translates to higher costs in case of mishaps.It is much smoother with significantly fewer misfires.