You’re sorting through spec sheets, comparing engines. One model lists a single overhead cam; another boasts a dual overhead setup. And suddenly you’re faced with the kind of question that doesn’t come with a simple answer: which is better—SOHC or DOHC?
Let’s make one thing clear: there’s no “better,” universally. It’s about fit. The right camshaft configuration depends entirely on what you expect from the engine—power, efficiency, ease of maintenance, or all of the above.
Where It All Started
Overhead camshaft designs go back further than you’d think—1903, if you want to be precise—but they weren’t common in everyday vehicles until the 1960s. At that point, manufacturers needed engines that could burn cleaner and perform better without getting bigger. This Jalopnik article is a solid primer if you’re curious about the timeline.
Since then, SOHC and DOHC engines have each found their place in the industry, depending on what the engine’s built to do.
Engine Designs
In the world of the internal combustion engine, camshaft design is more than a spec line—it defines how the engine breathes, performs, and even how long it lasts. Two of the most common architectures—SOHC (Single Overhead Camshaft) and DOHC (Dual Overhead Camshaft)—control the engine’s intake and exhaust valves in different ways, and those differences matter.
These configurations determine airflow into and out of the combustion chamber, affect fuel efficiency, and even influence how easy the engine is to work on. So, if you’re weighing options—or just trying to understand what powers your equipment—it’s worth taking a closer look at how these systems work, and where each one shines in the SOHC vs DOHC conversation.
SOHC: Straightforward, for a Reason
In SOHC engines one camshaft handles both inlet and exhaust valves, often through a basic rocker setup. Nothing elaborate, just a direct connection between what the engine needs and how it gets there.
You don’t need a blueprint to see the appeal. Fewer parts. Less to wear. Less to line up.
The real advantage isn’t obvious until you’ve driven or serviced one for a while. They tend to be mechanically lean—less friction, less resistance. Especially at lower RPMs, that pays off in better efficiency.
DOHC: Built to Respond
With DOHC engines, you get two camshafts—one manages intake valves, the other handles exhaust.
Engines with this setup usually run four valves per cylinder, which gives them more airflow potential. That alone improves how they perform across the rev range—not just at the top, but during transitions. Acceleration feels sharper. The engine reacts more intuitively.
But where this layout really earns its keep is in adaptability. Pairing DOHC with systems like variable valve timing lets the engine adjust on the fly, shifting valve behavior depending on load, speed, or driving conditions.
What Should Drive Your Decision?
Let’s be honest—you can’t just toggle between SOHC and DOHC. The cam setup is baked into the engine block, the cylinder head, and everything around them. So this isn’t about picking a part. It’s about choosing a platform.
If your priority is ease of service, lower cost, and dependable operation, SOHC is a solid call. It’s not exotic, but it works—and it keeps working, year after year.
If you’re chasing better airflow, more responsive throttle, or trying to meet modern performance standards, DOHC is where you’ll likely land. Whether you’re hauling heavy loads or optimizing for emissions and fuel efficiency, the DOHC configuration gives you more to work with.
Where Behind The 8 Fits In
At Behind The 8, we know engines come in all shapes, sizes, and cam configurations—and we’re here to make sure you get the right parts for your needs.
From dual overhead cam components to hard-to-find SOHC replacements, we stock the parts that keep diesel engines running hard.Working on something specific? Get a quote.
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