Max RPM from a Piston-Speed Limit

From MPS = stroke x RPM / 6, the RPM cap is 6 x MPS_limit / stroke. A 3.48 in stroke at a 4,000 ft/min street ceiling redlines at 6,897 rpm; a longer stroke lowers the cap for the same limit. Street/endurance ~4,000, performance 4,000-4,500, race over 4,500 ft/min. Average, not peak; guidance bands. A shop aid; the component makers' rpm ratings govern.

rpm_max = 6 x mps_limit_fpm / stroke_in (the mean-piston-speed relation MPS = stroke x RPM / 6 solved for RPM); mps_limit_ms = mps_limit_fpm x 0.00508.

The mean-piston-speed relation MPS = 2 x stroke x RPM solved for the RPM cap, the inverse of the mean-piston-speed tile, as compiled in the engine-building references, by name.

The mean-piston-speed relation is a public engine-building result; the regime bands are standard builder guidance.

Estimate. AHJ and licensed professional govern.

Field names used by the API: stroke_in, mps_limit_fpm, rpm_max

• RPM cap rpm_max = 6 x mps_limit_fpm / stroke_inengine-building references
• Regime bands street/endurance ~4,000, performance 4,000-4,500, race over 4,500 ft/minbuilder guidance
• Average not peak uses the average piston speed; a specific assembly's limit depends on the rods, pistons, and pinskinematics