Bottom Line Up Front
Yes, engines with three spark plugs in a single cylinder have been built, but they are few and far between because the extra plug adds cost, weight, and complexity.
Engines With Three Spark Plugs Per Cylinder – Rare But Real
Image: Engines With Three Spark Plugs Per Cylinder – Rare But Real – Performance Comparison and Specifications
Design & Looks
Putting three plugs into one cylinder is mainly a combustion‑efficiency trick. The idea is to create two smaller flame fronts that meet in the middle, burning the air‑fuel mix faster and more evenly. Manufacturers that tried this often used a special cylinder head with three evenly spaced spark‑plug holes.
Visually, the difference is subtle – you’ll see an extra plug wire or coil pack on the valve cover. The overall engine shape stays the same, which means the car’s exterior design is unchanged.
Performance & Mileage
When the three‑plug system works, it can improve low‑end torque and reduce emissions. The faster burn means the engine can run a bit leaner, giving a small boost in fuel economy. In practice, the gain is usually under 5% and only noticeable in specific operating ranges.
Because the system needs more precise timing, it often uses a sophisticated ECU that can control each plug independently. That adds reliability concerns – one failed plug can throw the whole cylinder out of balance.
Price & Rivals
The added parts and engineering make a three‑spark engine pricier than a comparable two‑spark or single‑spark design. Most car buyers don’t see enough benefit to pay the premium, so manufacturers stick with simpler solutions.
Below is a quick snapshot of the few production or prototype engines that have used three spark plugs per cylinder.
| Engine | Mileage (MPG) | Price (USD) | Top Features |
|---|---|---|---|
| Mitsubishi 4G63 Turbo (3SP) | 22 city / 29 highway | ~$4,800 (used) |
|
| Toyota 2JZ‑GTE Concept (3SP) | 18 city / 25 highway | ~$7,200 (prototype) |
|
| Mercedes M104 Prototype (3SP) | 20 city / 27 highway | ~$5,500 (demo) |
|
FAQ
- What is the main advantage of three spark plugs per cylinder? Faster and more even combustion, which can improve low‑rpm torque and slightly raise fuel efficiency.
- Why don’t more manufacturers use three spark plugs? The extra hardware raises cost, adds weight, and requires a more complex engine‑control system that many buyers don’t need.
- Is a three‑spark engine reliable for daily driving? It can be reliable, but a failure in any one plug can cause rough running, so regular maintenance is crucial.
What do you think about three‑spark engines? Share your thoughts in the comments below.
Source: Read Official News
