Horsepower.

[TT-(Moderator) 1,127]

No-load governed speed is 3600 rpm on the K series singles. (K-91 was 4000)

Newer engines are all relatively the same - 3400 to 3600 rpm.

MAXIMUM rpm varies on all engines.

(That would be the fastest speed the engine turns before the rod bolts stretch and break or the rod seizes to the crankshaft journal and the whole thing goes to pieces.) I've seen a few "little ones" turning in excess of 8500 rpm. :horseplay:

17 to 19 horsepower (or more) is not uncommon for the B & S engines used in the Junior Dragster cars...... engines that started out as 14 cubic inch 5hp models! :whistle:

[Curmudgeon 28]

Increasing RPM only increases RPM, not horsepower. Every engine has a peak output spot, the spot where RPM X torque (over simplified math example) yields the greatest number. This is at some point just pass peak torque where RPM's are going up faster than torque is coming down. Once the torque output is dropping faster than the RPM's can make up for it in the equation, horsepower will also drop.

"Go fast" engines typically spin faster for more horsepower, because of different cam profiles, enlarged ports, etc. which move the torque up the RPM range.

[Curmudgeon 28]

No-load governed speed is 3600 rpm on the K series singles. (K-91 was 4000)

Newer engines are all relatively the same - 3400 to 3600 rpm.

MAXIMUM rpm varies on all engines.

(That would be the fastest speed the engine turns before the rod bolts stretch and break or the rod seizes to the crankshaft journal and the whole thing goes to pieces.) I've seen a few "little ones" turning in excess of 8500 rpm. :horseplay:

17 to 19 horsepower (or more) is not uncommon for the B & S engines used in the Junior Dragster cars...... engines that started out as 14 cubic inch 5hp models!

Or the valves float. Or the points (if it has them) float, or or or. There is a limit.

The 28cu in Briggs, typically a 12HP model can be made souped up to about 40HP without too much effort as well. Just ask the lawn mower race guys......