Mean Piston Speed and Engines
The mean piston speed identifies the potential power loss and maximum Revolutions Per Minute (RPM) of an engine. Every car manufacturer has to identify the mean piston speed of their engine before launching it to ensure the accurate functioning of the car’s engine.
In this guide, we will provide you complete details about mean piston speed and its role in engine designing and performance.
What is Mean Piston Speed (MPS)
According to the definition, average piston speed refers to the speed of piston when it moves up and down in the cylinder bore during each crankshaft revolution. The speed of the piston is always changing as it completely stops at the top and bottom of the cylinder bore. Therefore, there are multiple formulas to calculate the speed of the piston at every angle in the cylinder bore. The most common and general way to calculate mean piston speed is:
Number 2 represents two positions inside the cylinder bore where the piston completely stops.
Relationship between MPS and RPM
The RPM in the car measures how many times the crankshaft rotates in one minute. Along with this, it also calculates the mean time taken by the piston to complete one cycle. Therefore, RPM and MPS are directly related in petrol and diesel engines. Any potential change in the speed of the piston can impact proper fuel combustion inside the cylinder which directly reduces RPM.
Mean Piston Speed and Engine Performance
Piston speeds create direct and significant impact on the performance and efficiency of an engine. The speed and time taken by a piston to complete its journey, actually determines the overall speed of a vehicle.
Power and Efficiency
MPS can increase or decrease the efficiency and power of an engine. If MPS is lower the power created by an engine will also decrease. Whereas, if the piston stays at one place for a longer period of time, it will decrease the efficiency of the engine. This is why the ratio between MPS and RPM is set as per the total power producing capacity of an engine.
In combustion engines, fuel consumption is dependent upon the air to fuel ratio. When the MPS is higher it provides less time to air to fuel ratio for burning which leads to incomplete combustion. This leads to black smoke from the exhaust and higher fuel consumption. Thereof, the disruption in MPS will impact fuel mileage of the vehicle, regardless of the number of fuel efficient habits that you adopt.
The higher MPS will multiply the magnitude and stroke pressure on different engine parts leading to their malfunctioning. The increased pressure will also cause wear and tear of rotating and revolving parts increasing engine oil consumption. Moreover, the increased pressure will reduce the overall life span of different engine parts.
What is Safe MPS
Safe piston speed is the maximum piston speed of a vehicle. At this speed pistons work effectively at highest efficiency. Around 26.9 m/s is the highest mean piston speed that is only possible in Formula 1 cars. However, some Audi car models containing 5.5L V-10 engines can achieve this maximum piston speed.
This was all about the Mean Piston Speed that impacts on engine performance. Pistons in vehicles are prepared from durable material with higher cylinder bore circumference to meet MPS. If you are interested in experiencing the MPS of vehicles, browse through some of these used cars for sale in the UAE with higher cylinder bore circumference. We have also enlisted some of the models for you with perfect MPS.
Stay tuned to UAE’s top auto blog for more information on piston speed.