This power plant is a screamer, with peak torque at 4,500 r.p.m. and peak horsepower at 6.800 r.p.m.

Among the tweaks was a variable intake system that opened an extra set of butterflies as rpm increased, allowing great low-end torque along with 145 peak horsepower.

This gave lightweight, compact dimensions, extremely fast throttle response and high peak horsepower.

Torque is up to 86lb ft from 65lb ft, while peak horsepower rises 12bhp to 127bhp, enough for Harley to fire it up a drag strip in California.

These engines can be tuned in a manner where peak horsepower is reduced in order to have a wider torque band for easier throttling in any circumstance and have greater reliability.

The peak horsepower might be 5000 RPM.

Forget what those specifications imply about outmoded technology: with 350 peak horsepower, and bountiful torque at low speeds, the Corvette is very forgiving if you're lazy with the six-speed manual gearshift.

Though still down a bit on peak horsepower compared with some rivals, the 851 compensated with strong midrange punch, light weight afforded by exotic materials, and chassis dynamics second to none.

This smaller engine is higher revving and produces a lower peak horsepower than the larger engine used in the 999.

The RPM at which peak horsepower occurs is typically increased as duration increases at the expense of lower rpm efficiency (torque).