When perusing car spec sheets, you’ve likely noticed abbreviations such as SOHC and DOHC appearing in sections about engine information. To some purchasers, these terms seem tech-sounding and bewildering. Knowing them, however, can provide a better understanding of how your automobile engine operates, as well as what it offers in terms of engine performance, fuel economy, and maintenance.
In this blog, we will demystify the differences between SOHC and DOHC, providing a clear understanding of how these two engine types differ. We will discuss what each is short for, how their strengths and weaknesses compare, and which is more sensible given varying types of drivers in India.
What is SOHC?
SOHC: Abbreviation of Single Overhead Camshaft. This engine configuration features a single camshaft located above the cylinder head. This alone operates the intake and exhaust valves, directing air and fuel into the combustion chamber, as well as exhaust gas out.
Advantages of SOHC Engines
- Simplicity: With fewer moving parts, the design is straightforward and easier to maintain.
- Lower Cost: Cars with SOHC engines are often less expensive to produce, which helps keep vehicle costs down.
- Compact Size: SOHC engines typically occupy less space under the hood, making them suitable for smaller cars.
- Decent Efficiency: They provide good mileage in city and highway conditions, especially in budget-friendly cars.
Disadvantages of SOHC Engines
- Performance Limitations: Since one camshaft handles both intake and exhaust valves, it restricts the flexibility of valve timing.
- Lower Power Output: Compared to DOHC, SOHC engines generally produce less power at higher RPMs.
SOHC engines are commonly found in smaller cars, where affordability and fuel economy are more important than outright performance.
What is DOHC?
DOHC is an abbreviation of Double Overhead Camshaft. In this configuration, there are two camshafts located on top of the engine cylinder head. One camshaft operates an exclusive intake valve, and the other operates an exclusive exhaust valve. This enables engineers to fine-tune valve timing to provide improved airflow, combustion, and performance.
Advantages of DOHC Engines
- Higher Performance: With separate camshafts, valve operation is more precise, allowing engines to rev higher and produce more power.
- Better Efficiency: Improved airflow can lead to better combustion and, in many cases, higher fuel efficiency.
- Supports More Valves: DOHC designs commonly use 4 valves per cylinder (2 intake, 2 exhaust), which improves breathing and performance.
- Modern Preference: Most modern cars, particularly those in the premium and performance categories, utilise DOHC engines.
Disadvantages of DOHC Engines
- Higher Cost: The design is more complex and expensive to manufacture.
- Maintenance Complexity: The presence of more moving parts means that repairs and servicing can be more costly.
- Slightly Bigger Size: DOHC engines are usually larger and heavier than SOHC ones.
DOHC engines are widely used in mid-range and premium cars today, as they strike a balance between performance, refinement, and efficiency compared to SOHC setups.
SOHC vs DOHC: Key Differences
While both SOHC and DOHC engines serve the same purpose of controlling intake and exhaust valves, their design creates noticeable differences in performance, cost, and efficiency.
Comparison Table – SOHC vs DOHC
| Feature | SOHC (Single Overhead Camshaft) | DOHC (Double Overhead Camshaft) |
| Number of Camshafts | 1 camshaft per cylinder head | 2 camshafts per cylinder head |
| Valve Control | Controls both intake and exhaust valves | Separate camshafts for intake & exhaust |
| Performance | Adequate for daily driving, limited at high RPM | High performance, better power at high RPM |
| Fuel Efficiency | Generally good, especially in small cars | It can be better due to improved combustion |
| Cost | Cheaper to produce and maintain | More expensive to manufacture and repair |
| Size & Weight | Compact and lighter | Larger and slightly heavier |
| Common Usage | Entry-level hatchbacks, budget cars | Mid-range to premium and performance cars |
SOHC vs DOHC: SOHC is a simpler and less expensive engine, best suited for small, economy vehicles. DOHC provides improved potency and refinement, which is why it is king in current mid-range and high-end cars.
Which is Better: SOHC or DOHC?
When choosing between SOHC and DOHC, it all depends on what you value as an automobile purchaser.
When affordability and ease of operation are most important, SOHC engines offer a good compromise. They are less costly to own, less expensive to build, and commonly used in small cars such as those intended for city driving and economy.
Conversely, if refinement, performance, and new technology are your primary concerns, DOHC is the outright victor. With wider valve control and the ability to rev a higher number of valves per cylinder, DOHC engines have higher power output, smoother pickup, and, in most instances, higher efficiency.
Indian Market Conditions
- SOHC Engines are still found in some budget-friendly hatchbacks and older models, where cost savings are a priority.
- DOHC Engines dominate today’s market, as most new cars in India, from hatchbacks like the Hyundai i20 to SUVs like the Kia Seltos, use DOHC setups for better performance and compliance with emission norms.
In a nutshell, most Indian buyers opt for a DOHC engine, as it strikes a balance between performance and economy. In contrast, the SOHC is more suitable for start-ups, where cost and maintenance are key considerations.
Why This Matters for Indian Car Buyers
Understanding SOHC vs DOHC isn’t just for car enthusiasts; it has practical implications for everyday buyers in India.
Fuel Efficiency vs Performance
Indian customers tend to look for mileage. SOHC engines, being simpler, offer good mileage at lower prices. DOHC engines, on the other hand, can achieve good mileage while also offering higher engine performance, making them suitable for both highway and mixed usage driving.
Maintenance and Repair Costs
SOHC engines are less expensive to repair due to their fewer moving parts. For price-conscious buyers in minor cities, this is a consideration. DOHC engines, being more sophisticated, are more expensive to repair.
Regulatory and Emission Norms
BS6 and future discharge standards are driving manufacturers towards DOHC engines due to improved control of emissions and combustion. This is driving DOHC as the new industry standard for India.
Market Availability
The majority of new vehicles in India, ranging from small cars like the Baleno and i20 to crossovers such as the Nexon and Creta, employ DOHC Engines. SOHC configurations are becoming increasingly less common and are now found only in older or entry-level cars.
Resale Value
DOHC cars have a perception of higher modernity and sophistication, which will have a favourable effect on their resale value compared to SOHC cars.
Simply put, understanding SOHC vs. DOHC allows Indian purchasers to select vehicles that most closely align with their requirements for fuel efficiency, finances, and long-term appreciation.
Conclusion
When comparing SOHC vs DOHC, it is a case of two engine types that have their merits. The SOHC is a less complex and more affordable engine that is efficient in daily use and is suitable for small and inexpensive vehicles. The DOHC engine offers higher output, superior refinement, and is commonly found in contemporary high-performance vehicles.
DOHC versions have become the standard in most new cars among Indian buyers due to their conformance to emission norms and a good balance of performance and economy. SOHC versions areília present in a few entry-level cars but are becoming obsolete.
If you’re car shopping and see these terms in the spec sheet, understanding the difference between SOHC and DOHC will help you make a wiser purchase – whether mileage is important to you, cost is a concern, or high-end performance is desired.
FAQs on SOHC vs DOHC
Q. What does SOHC mean in a car engine?
SOHC stands for Single Overhead Camshaft. It utilises a single camshaft to control both the intake and exhaust valves in the engine.
Q. What does DOHC mean in a car engine?
DOHC stands for Double Overhead Camshaft. It utilises two camshafts one for the intake valves and one for the exhaust valves, to deliver improved airflow and performance.
Q. Which is better: SOHC or DOHC?
In the SOHC vs DOHC comparison, DOHC engines usually win for performance, refinement, and modern features. SOHC engines, however, are cheaper to maintain and more compact.
Q. Which gives better mileage: SOHC or DOHC?
SOHC engines often provide good mileage due to their simple design. However, DOHC engines can also be fuel-efficient because they optimise combustion more effectively.
Q. Are SOHC engines still used in India?
Yes, but they’re mostly found in older or entry-level models. Most modern cars in India now use DOHC engines.
Q. Why do manufacturers prefer DOHC engines now?
DOHC engines allow better control of valve timing, improved combustion, and compliance with stricter emission norms, making them the preferred choice today.
Q. Is maintenance cost higher for DOHC engines?
Yes. DOHC engines have more moving parts, which makes them slightly more complex and costlier to maintain compared to SOHC engines.
Q. Do both SOHC and DOHC engines support multiple valves per cylinder?
SOHC can support multiple valves, but with limitations. DOHC engines are better suited for four valves per cylinder, which improves breathing and performance.
