The past century has seen significant developments in the high performance internal combustion engine. These changes were driven in the first 50 years by accelerated technology due to two World Wars. A study of the engines in the period 1914–1918 and 1939 to 1944 is interesting in so much as many of the current designs of modern engines were in place. The materials and most importantly the computing power were simply not available. In 1960, a four cylinders normally aspirated race engine produced less than 100 BHP (74 kW) per liter capacity; today this is the norm for standard production car engines. A major thrust in the development of high performance engines came with the introduction of Formula 1 racing, as we understand it today in the early 1960’s when the engine capacity was reduced to 1.5 liters and the engines were normally aspirated. This lead to the onset of high revving engines than ran through to 12,000 rev/min, but still retained a flat BMEP (brake mean effective pressure) curve in excess of 1.4 MPa peak and at least 1.1 MPa from 4,500 rev/min through to 12,000 rev/min. In the course of some 45 years power per liter has risen from 100 BHP to 300 BHP (74–220 kW) and dynamometers and specialist instrument design has kept pace with this rise in efficiency. The paper will follow these trends and discuss in some detail the instrumentation that was available to early engineers and follow progress through today, culminating in low inertia dynamometers that are capable of continuous running at 30,000 rev/min and absorbing 2,500 BHP (1,800 kW).