This Famous P-51 Air Racer's Engine Test Is A Mechanical Thunder Storm

Precious Metal is a staple of the air racing community. The highly modified P-51’s striking yellow and polished paint job and its contra-rotating propellers are features that make it stand out, but the sights and especially sounds of its supped Merlin engine during a test run equates to a visceral crescendo of delight and amazement for anyone who loves mechanics and things that go really, really fast.

Top video and one above courtesy of master photographer Mike Killian, check out more of his work over on his Facebook page, you will be amazed.


Flames, grunts, putters and the steadying hum of startup are followed by a settling yet increasingly violent roar as Precious Metal’s engine output increases.

Then there’s that propeller that seems more like it was meant to conquer medieval cities than claw a plane through the air at 500 mph just 50 feet over the desert floor.

Unlimited Air Racing teams that fly Mustangs take Rolls Royce Merlin V-12 Engines (or the up-sized Griffon evolution of the Merlin in the case of Precious Metal), considered holy by many and priced accordingly, and pump their horsepower up by almost twice that of stock. This, along with fine-tuning the perfect propeller, and constantly clipping and streamlining the Mustang’s already sleek airframe and adapting its flight controls accordingly, is all in an attempt to make it around an 8.2 mile course a little faster.

Unlimited air racing remains the fastest racing sport in the world, and Precious Metal along with a gaggle of racing icons are about to go to war over Stead Field just outside of Reno on September 16th. Make it if you can; it is one of the most amazing spectacles you will ever see and hear.

Update note: Made change to mention the Griffon engine configuration with contra-rotating propellers on Precious Metal.


Contact the author at

Share This Story

Get our newsletter


Tentacle, Dutchman, drives French

The Unlimiteds go flashing through the racecourse, engines howling, air shearing, heat waves streaming. Four hundred eighty miles an hour is 8 miles a minute, and the elite racers take about 70 seconds to cover the 9.1 mile Reno course. If you could take a souped P-51 racer flying the circuit at Reno, slow time down, and examine just one second, what would you find?

In that one second, the V-12 Rolls-Royce Merlin engine would have gone through 60 revolutions, with each of the 48 valves slamming open and closed 30 times. The twenty four spark plugs have fired 720 times. Each piston has traveled a total of 60 feet in linear distance at an average speed of 41 miles per hour, with the direction of movement reversing 180° after every 6 inches. Three hundred and sixty power pulses have been transmitted to the crankshaft, making 360 sonic booms as the exhaust gas is expelled from the cylinder with a velocity exceeding the speed of sound.

See the rest at…aptly called One Second in the Life of a Racer

Another great fact, which I unfortunately can’t find a link to, is that, apparently, those Unlimiteds get some extra power from raising boost beyond what raises prop speed. So why does that work, if you’re already nudging your prop tips against Mach 1 speeds? Gulping even more air and burning even more fuel (and ADI fluid) increases the flow of exhaust gasses, contributing to more propulsion!