![]() First off, the bottom end features a four-bolt main cap to ensure the crankshaft is secured in place. Although cast-iron offers a substantial benefit in strength over aluminum, Mitsubishi took the necessary steps to ensure the durability of the 4B11T bottom end. The cast-iron 4G63 engine, seen in previous EVO platforms, has proven to withstand high-horsepower production. The cooler running engine also reduces emission production by lowering the engine’s nitrogen oxide (NOx) production. As a result, cooler piston and oil temperatures improve engine durability and longevity. In addition, the superior thermal efficiency of aluminum increases heat transfer to the cooling system. The reduced engine weight helps improve the vehicle’s fuel economy. The new EVO engine weighs 26 lbs less than the 4G63. One of the obvious advantages of the aluminum bottom end is weight savings. The biggest change made to the EVO heritage was the move to an all- aluminum short block. To remain compliant with EPA while being able to make more power, Mitsubishi developed its new 4B11T engine that debuted in its EVO X. ![]() Detuned to meet these limits, the 4G63 engine would max out at 250 horsepower. The reason was simple: new, more-stringent emission requirements. Many questioned why Mitsubishi did away with an iconic and nearly indestructible engine that has set records for the last two decades. When EVO fans discovered their beloved 4G63 would be replaced with an all-aluminum engine, outrage ensued. ![]() While few embrace it, change must happen in order to evolve and improve. ![]()
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