The Great Debate: Crossplane vs Flat Plane Firing Order

When it comes to internal combustion engines, there are many nuances that can affect their performance and efficiency. One such aspect is the firing order pattern used in engine design - specifically, whether an engine uses a crossplane or flat plane configuration.

So what does this terminology mean exactly? In simple terms, 'flat plane' and 'cross plane' refer to the angle at which the crank journals are positioned relative to each other within the engine block. This seemingly minor detail has significant implications for the overall behavior of the engine.

In a traditional crossplane design, the crankshaft's firing order is arranged in an angular pattern, with pistons on opposing banks firing 180 degrees out of phase from one another. This arrangement helps to reduce vibrations and improve smoothness at high RPMs by averaging out the forces generated during combustion.

On the other hand, flat plane engines have a more linear firing order, where pistons fire directly across from each other in an alternating pattern. While this design can provide better low-end torque due to its increased compression ratio, it also introduces additional vibrations and harmonics that must be carefully managed through engine balancing and tuning.

So why do manufacturers opt for the flat plane configuration? According to some insiders, certain high-performance applications - such as those found in limited-production sports cars like the M1 - require this design to effectively mitigate the intense vibration generated at extremely high RPMs (in excess of 18,000 rpm). By using a flat plane crankshaft, engineers can better control these vibrations and create a smoother overall driving experience.

In conclusion, while both crossplane and flat plane firing orders have their own advantages and disadvantages, understanding the fundamental differences between them is crucial for engine enthusiasts seeking to optimize performance or diagnose issues with their vehicles. Whether you're an engineer designing high-performance engines or simply looking to improve your ride's power delivery, grasping these subtleties can make all the difference in achieving optimal results.

Crossplane vs flat plane firing order