8 Breakthrough Engine Designs that Created the Modern Automobile Engine
Today’s highly-efficient engines combine many different technologies. Let’s look at the engines in which each of these key concepts were first introduced.
For the sake of simplicity, we’re going to define a modern engine as one that has four cylinders inline, two belt-driven camshafts that reside in the top of the cylinder head directly acting on two intake and two exhaust valves per cylinder. Further the engine is force-inducted to improve its efficiency, primarily via turbocharging. Fuel is injected directly into the engine with great precision via an electronic computer that controls both fuel delivery and ignition timing to maximize power and efficiency. Here goes:
First Modern Engine Architecture – 1912 Peugeot L45
In 1912, a 27 year old engineer named Ernest Henry, then working for Peugeot, set down what would become the basic architecture for most automobile engines in production today. It was an inline four cylinder design, with double overhead camshafts (DOHC), four valves per cylinder, and a hemispherical combustion chamber. The original design used shafts and bevel gears to drive the camshafts, which were replaced with gears in 1913, along with the addition of dry sump lubrication. The engine was very successful in racing, winning both the French GP in 1912 and 1913 and the Indianapolis 500 in 1913.
First Gasoline Direct Inject – 1954 Mercedes-Benz 300SL
The 3.0 L Mercedes-Benz M186 ‘big six’ was produced from 1951 until 1967 with no change in its 3.0 L displacement derived from a slightly under-square 85 mm x 88 mm bore and stroke. It featured an overhead cam, and an aluminum head with an innovative diagonal head-to-block joint that allowed for oversized intake and exhaust valve. In 1954 Mercedes added fuel injection for the 300SL “Gullwing” and its roadster counterpart, in this case direct fuel injection (as in a diesel engine), but in this case a gasoline engine. The Bosch mechanical pump can be seen in the lower right of the illustration above and trace the fuel line to the injector that passes through the engine black to reach the combustion chamber. Direct injection, along with the increase in compression ratio it allowed, produced 215 hp from an engine that on carburetors could produce only 150 hp.
First Turbo Engines – 1962 Oldsmobile F-85 Jetfire and 1975 Porsche 930
In 1961 GM introduced its 215 CID aluminum block V8 for the Buick, Oldsmobile, and Pontiac divisions (each had added their own uniques tweaks to the engine). For 1962 Oldsmobile offered a version with a Garrett turbocharger, becoming the first turbocharged production car (Corvair would join it a few weeks later). Without modern engine controls, performance was problematic, with “spark knock” occurring under load. A water/alcohol injection system was developed, but rarely refilled by owners and the turbo Olds faded after just a few years less than 4,000 units sold.
Skip ahead a decade. Turbocharging, which had since been relegated to oval track racing due to poor throttle response, was reinvented by Porsche and the Penske team led by Mark Donohue, which won two championships in the turbocharged Porsche 917 with George Follmer and Donohue driving. Concurrently Porsche was examining turbocharging for its 911-based race car. The rules required production versions of the car, so the Porsche 930 Turbo was born. Using Bosch K-Jetronic fuel injection, crude by today’s standards but state-of-the-art in the early 1970s, Porsche created a practical street car and the dominating 935 race car using a turbo engine, and triggered a rebirth in interest among manufacturers in turbocharging.
First Toothed-belt Overhead Camshaft Drive Belt – 1966 Pontiac Tempest
In the 1966 model year Pontiac introduced to the world the first overhead camshaft engine with a rubber toothed-belt drive . Based on the standard 230 CID Chevrolet Straight-6, but with block and head castings unique to the OHC. Both head and block were grey iron; only the combination cam carrier/valve cover was aluminum. Pontiac had wanted an OHC engine to improve its stodgy image with buyers, but the traditional options of gear or chain drive were noisy, complex, heavy, and expensive. Pontiac’s eventual solution, developed in conjunction with Uniroyal (now part of Michelin), was a one-inch wide nylon fabric belt, impregnated with neoprene rubber and reinforced with fiberglass. The reinforced rubber belt proved to be strong and durable, demonstrating minimal wear in high-mileage testing. Since proving itself on the Pontiac OHC engine, the toothed-belt has become the standard of the industry.
First Linerless Aluminum Engine – 1971 Chevrolet Vega
The 1971 Chevrolet Vega was the first true production automotive engine with a liner-less hypereutectic aluminum cylinder bore as the wear surface. Despite the car’s reputation, the cylinder concept was ahead of its time. A hypereutectic alloy is saturated with silicon particles dispersed throughout the alloy like chocolate chips in cookies. “Saturated” is the key word, as above the saturation point (the “eutectic” point), silicon will precipitate out in crystal form. Typically, this begins to take place at around a 12% silicon concentration. When properly finished, hypereutectic aluminum cylinder bores present a surface to the piston rings that’s a smooth as glass. The resulting engine has lower friction, improved heat dissipation, reduced weight, easier to recycle, lower manufacturing cost and can be smaller than an equivalent aluminum block with cast-iron cylinder liners.
First Digital Engine Management System – 1979 BMW 732i
The first complete engine management system was the Bosch Motronic ML-1, as integrated into the 1979 BMW 732i. The Motronic system integrated ignition spark timing with fuel injection technology. The engine control module (ECM) received information regarding engine speed, crankshaft angle, coolant temperature, and throttle position. An air flow meter also measured the volume of air entering the induction system. If the engine is naturally aspirated, an air temperature sensor is located in the air flow meter to work out the air mass. However, if the engine is turbocharged, an additional charge air temperature sensor is used to monitor the temperature of the inducted air after it has passed through the turbocharger and intercooler, in order to accurately and dynamically calculate the overall air mass. This data was compared to preprogrammed maps inside the ECM, which instructed the operation of the ignition and fuel injection systems. And while systems have become more sophisticated, with increased and faster computing power, along with the ability to monitor a greater number of sensors, the systems still have their roots in the original Motronic ML-1.
First Compacted Graphite Iron (CGI) Cast Block in a Gasoline Engine – 2015 Ford F150 2.7 L EcoBoost V6
Compacted Graphite Iron has actually been around since the 1940s but hasn’t come into widespread use until recently. What makes CGI different than regular gray iron is that the graphite particles are shorter and thicker. This results in stronger adhesion between the graphite and the iron giving the material greater strength. A strange, but very useful, property of CGI is that its stronger the thinner it’s cast (to a point of course). CGI first found application for brake rotors on high speed trains in Europe, then started being utilized by commercial diesel engine manufacturers. Audi has used CGI in its diesel engines for several years, and Ford, Chevrolet, and Toyota all cast their NASCAR race block blocks in CGI. The first application in a mass-produced gasoline engine is the Ford 2.7 L EcoBoost V6 for the F150 truck. It’s a unique design where the basic block is cast in CGI and sits in what appears to be a cradle that Ford refers to as a Ladder Structure. Very clever.
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