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Clearly, in this example, the angle between the crank and the rod is not a right angle. Summing the angles of the triangle 88.21738° + 18.60647° + 73.17615° gives 180.00000°. A single counter-example is sufficient to disprove the statement "velocity maxima/minima occur when crank makes a right angle with rod".
The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution (or alternatively: two strokes per one crank revolution) and a '60' to convert seconds from minutes in the RPM term.
The formula was calculated from total piston surface area (i.e., "bore" only). The factor of 2.5 accounts for characteristics that were widely seen in engines at the time, such as a mean effective pressure in the cylinder of 90 psi (6.2 bar) and a maximum piston speed of 1,000 feet per minute (5.1 m/s).
As piston engines usually have their maximum torque at a lower rotating speed than the maximum power output, the BMEP is lower at full power (at higher rotating speed). If the same engine is rated 72 kW at 5400 min −1 = 90 s −1 , and its BMEP is 0.80 MPa, we get the following equation:
Current Formula One engines, maximum piston acceleration (up to 10,000 g before rev limits) [24] 10 5: 100 km/s 2: 102 000 m/s 2: 10 400 g: A mantis shrimp punch [25] 152 210 m/s 2: 15 500 g: Rating of electronics built into military artillery shells [26] 196 400 m/s 2: 20 000 g: Spore acceleration of the Pilobolus fungi [27] 304 420 m/s 2: 31 ...
is the Mach number, which is taken in the limit of zero p 0 {\displaystyle p_{0}} is the flow's stagnation pressure This relationship is valid for the flow of incompressible fluids where variations in speed and pressure are sufficiently small that variations in fluid density can be neglected.
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An engine is described as undersquare or long-stroke if its cylinders have a smaller bore (width, diameter) than its stroke (length of piston travel) - giving a ratio value of less than 1:1. At a given engine speed, a longer stroke increases engine friction and increases stress on the crankshaft due to the higher peak piston acceleration.