MCE-5 to Debut 220-HP 1.5L Engine with Variable Compression Ratio at Geneva

by Scott_Evans

If you know much about how engines work, the idea of a variable compression ratio seems almost crazy. The idea isn't new, in fact Saab claims to have been working on it since the 1980s, but it's never been commercially viable. Nine years after the last attempt to bring it to market, the variable compression engine is back for another round and it's got some big promises to keep. This time, another European company is giving it a go. France-based MCE-5 Development was founded in the year 2000 by a small group of engineers from a school in Paris dedicated to developing VCR technology. The company quickly teamed up with a number of European automakers and auto parts suppliers and has been trying to perfect an engine design originally conceived back in 1997. Here's what they've come up with: The gasoline-powered, four-cylinder MCE-5 VCRi (for Intelligent Variable Compression Ratio) engine uses a two-state turbocharger, displaces 1.5L and pumps out an impressive 220 hp and 310 lb-ft of torque -- numbers comparable to engines with much larger displacement and more cylinders. MCE-5 says the engine will get 35 mpg and emit only 0.56 grams of CO2 per mile. Sound too good to be true? Wait, it gets better. MCE-5 says that the engine shown here is just a preliminary model and will soon be upgraded. For 2010, MCE-5 will add direct injection, optimized combustion chambers and advanced temperature management of the engine, cylinder head, piston, and exhaust. All of these upgrades will help the revised engine produce a whopping 266 hp and 347 lb-ft of torque, all from just 1.5L. It'll even bump fuel economy over 40 mpg and drop CO2 emissions under 0.5 lbs per mile. MCE-5 is optimistic even here, suggesting that emissions could drop under 0.43 lbs per mile by 2012-2013 and fuel economy could improve even further. The last time we saw this kind of technology was the 2000 Geneva Motor Show, where Saab rolled out the Saab Variable Compression engine, which could alter its compression ratio while running. To do so, Saab attached one side of the cylinder head to the cylinder block with a hinge, then placed a lifting mechanism on the other side of the block. When activated, it would tilt the cylinder head four degrees up to one side in a similar fashion to opening the lid of a piano. Doing so would increase the volume of the combustion chambers, lowering the compression ratio. Saab claimed that the technology could change the compression ratio from 8:1 to 14:1 while the engine was running for optimal efficiency and performance, yielding 225 hp and 224 lb-ft of torque on 40 psi of boost from a supercharged 1.5L engine. MCE-5, though, has other ideas. Rather than move the cylinder head around, MCE-5 appears to be manipulating the stroke of the pistons. In a traditional internal combustion engine, each piston is attached directly to the crankshaft by a rod. MCE-5, though, has added an intermediary in the form of a special gear. This gear acts as both a gear and a rocker arm, and special hydraulic jacks embedded in the engine block next to the cylinders manipulate this rocker gear in order to change the length of the piston stroke, thereby changing the volume of the combustion chamber and therefore the compression ratio. MCE-5 says their system can change the compression ratio from 7:1 to an incredible 18:1 and the system can change the ratio from the lowest to the highest in less than 100 milliseconds. The system will supposedly allow the gasoline engine to run on compression like a diesel in some cases, use the more-efficient Atkinson Cycle and run various other fuels like bio-fuels and compressed gasses. The system can even control each cylinder separately, allowing all four cylinders to operate at different compression ratios, each one optimal for that cylinder. At least, that's how we understand it. The new design is very complex and MCE-5 never explains exactly how the mechanics of the system work, so our understanding is a bit hazy. If you're mechanically inclined, pop over to MCE-5's website and have a look around at their diagrams, videos and other materials and see what you can make of it. MCE-5 claims that because their system is based on simple mechanics and utilizes all of the same construction techniques as conventional engines, the cost of putting an MCE-5 engine in a car is less the $700 more than using a conventional engine. The company will be showing off their prototype nestled under the hood of a Peugeot 407 at the 2009 Geneva Motor Show next week, and who knows, maybe we'll see it on the road someday. Source: MCE-5 Development