Key to engine's performance: stroke/bore ratio.
The volume of engine cylinders is determined by its bore and stroke. These two calibers differ according to application usage and mostly rely on environmental commitment.
Cylinders with longer stroke/bore ratio, experience small surface area where combustion occurs in the chamber (especially high compression ratio engines). This in-turn leads to less heat transfer from the cylinder and thus building more pressure that allow the engine to extract more mechanical energy to rotate the crankshaft. Moreover, high stroke to bore ratio could be more useful for engines with limited valve-train number per cylinder such as SOHC and OHV. In such design, the distance fresh air has to travel from the intake port to the exhaust one increases resulting in higher scavenging effect, more breath-out, and an increase in volumetric efficiency. The engine can then draw more fresh air to each cylinder at each cycle where no residual gases are left.
Previously mentioned that stroke to bore ratio is not embodied for performance only, but also for environmental sake. The higher stroke to bore ratio, the more distance the piston is allowed to move down through expansion stroke, the cooler the exhaust stream is obtained. Cooler exhaust stream means less hazard NOX emissions.
No limits in engine design and innovations…. Obviously F1 engines have high bore to stroke ratio which make these engines superior in being very high revving engines; (surely aided with the use of light components to reduce inertia and special valve-train design). The above simulation declares how different bore/stroke ratios affects piston speed. Low stroke engines, have lower Mean Piston Speed than stroker ones: {Mean Piston Speed is a function of stroke and RPM, so for high Bore to Stroke ratio engines, the piston traveling speed is lower (since stroke is shorter), that's why these engines can be set to rev-up higher and thus extracts more power at high revving ranges}. Additionally, having shorter stroke serves in lowering stress exerted on piston, connecting rods, piston rings, and reduce secondary vibration.Thus rationality says that it can be revved up more smoothly!