Mean Piston Speed and RPM-Limit Reading
Whether an rpm target is safe for the stroke, the single best predictor of reciprocating stress: MPS = stroke_in x RPM / 6 (ft/min), independent of bore. A 3.48 in stroke at 6,000 rpm runs 3,480 ft/min (street/endurance); rev to 7,000 and it hits 4,060 (performance) - and a longer 4.00 in stroke would already sit at 4,000 at 6,000 rpm, the trade a stroker accepts. Street builds stay under ~4,000, performance 4,000-4,500, race over 4,500. Average, not peak; guidance bands. A shop aid; the component ratings govern.
Formula and source
mps_fpm = stroke_in x RPM / 6 (= 2 x stroke x RPM); mps_ms = mps_fpm x 0.00508; regime by ft/min band.
The mean-piston-speed relation MPS = 2 x stroke x RPM and the practical rpm-limit bands, as compiled in the engine-building references, by name.
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