What is the difference between DOHC and SOHC engines?

[LeMaximus]

The main differences between DOHC and SOHC engines: SOHC: Single Overhead Camshaft performs well in urban driving with strong low-end torque, fuel efficiency, simple structure, low manufacturing cost, and low maintenance expenses. However, it lacks sufficient power reserve at high speeds. DOHC: Double Overhead Camshaft delivers strong high-end power, high emission efficiency, and is suitable for high-speed driving. It features a complex structure, high manufacturing cost, and expensive maintenance. Here is an introduction about DOHC and SOHC: SOHC engine refers to an intake system that uses a single overhead camshaft, meaning one intake valve and one exhaust valve. DOHC engine refers to an intake system that uses double overhead camshafts, typically with multiple valves per cylinder, commonly 4 valves (i.e., 2 intake valves and 2 exhaust valves).

[VonViolet]

When it comes to the difference between DOHC and SOHC engines, as someone who's been driving for decades, I know it all too well. DOHC stands for Double Overhead Camshaft design, which uses two independent camshafts to control the intake and exhaust valves separately. It's a bit more complex in structure, but the advantage is better responsiveness at high RPMs, more aggressive power output, and stronger acceleration push, making it particularly suitable for performance cars. On the other hand, SOHC uses a single camshaft to manage all valves—simple, reliable, and cheaper to maintain. It offers smooth and fuel-efficient driving in daily city commutes, with lower fuel consumption, which is why most economy cars use it—cost-effective and worry-free. The key point is, if you're into modifications, DOHC offers more flexibility, like adjusting valve timing, though it's trickier to repair. SOHC, conversely, rarely runs into major issues. As an experienced driver, I’d say: if you love tuning, prioritize DOHC; if you want hassle-free driving, SOHC is the way to go—don’t just focus on specs.

[OMicah]

As an average family car user, I find the DOHC vs. SOHC issue really impacts the wallet. Simply put, DOHC engines have two camshafts separately controlling intake and exhaust valves, delivering stronger power and faster acceleration, but the engine is heavier with relatively higher fuel consumption and some noise at high speeds. SOHC uses a single camshaft, making it lighter, quieter, and more fuel-efficient—saving hundreds on gas annually while maintaining smooth city driving in traffic. Don’t overlook this detail when buying a car: SOHC models like the classic Honda Accord have lower maintenance costs and cheaper repairs, while DOHC turbocharged cars offer stronger performance but pricier fixes, especially for camshaft bearing replacements. From a practical standpoint, prioritize maintenance intervals and fuel savings over dealership upsells for high-performance variants—pragmatism matters most.

[AllieLynn]

I'm an experienced auto mechanic, and DOHC and SOHC are common differences under the hood. DOHC uses two separate camshafts to independently control the valves, with a more complex design requiring precision parts. It's harder to repair, costs more in labor, and tends to have issues like faster valve wear. SOHC, on the other hand, uses a single camshaft to manage all valves—sturdier and more durable. During routine oil changes, it's usually hassle-free, with simpler disassembly and cheaper, more readily available parts. Comparatively, SOHC is slightly more fuel-efficient and leads to smaller repair bills. Many DOHC car owners complain about noise and rattling during maintenance, often needing timing chain adjustments, while SOHC engines rarely require major overhauls. For new car owners, I’d recommend choosing SOHC to minimize repair headaches and keep the car running smoothly for years. Just remember to regularly check chain tension—don’t let small issues escalate.