For months on end leading to the debut of the newest Mitsubishi Evolution, anticipation ran high among automotive enthusiasts as they sat patiently licking their chops for their chance to purchase the new Evo x. when the time had finally arrived, interestingly enough the added hype we had seen within the past few months has been met with a flurry of mixed emotions and cautious buyers.

Green Giant
Word on the street had quickly risen that Evo x's new 4B11 powerplant used a smaller exhaust camshaft with less lift and duration. Adding to the troubling news was Mitsubishi's new outlook on going environmentally green that was relevant even on the new Evo, as they implemented environmentally friendly exhaust valves that eliminated the once sodium-filled valves found on the Evo Ix. These minor changes paled in comparison to the shocking news that Mitsubishi's cast-iron block, which offered exceptional durability in all previous models, was replaced with a more conventional open-deck aluminum-alloy setup.

Preliminary news for the Evo x was looking grim for Evo enthusiasts and those reporting on the findings. Or at least that was until we received exciting news that the 4B11 engine had been carefully reverse engineered by Tomei Powered of Japan. Tomei engineers have diligently studied the 4B11's internal design in order to fully educate themselves before even attempting to lift a finger in fabricating high-performance aftermarket products. Now that's what you call dedication, folks. From the valvesprings to the piston design, Tomei Powered has carefully analyzed and recorded every conceivable part on the engine to the minute detail with some positive results. Prepare yourself as the Tomei engineers spit knowledge and breakdown the newest Mitsubishi 4B11 engine while comparing it to the previous 4G63 powerplant in their official Evo x Technical Report.

The Obvious Difference
Following the public release of the Mitsubishi Evo x, Tomei Powered quickly acquired and disassembled the newest 4B11 powerplant to begin their research. Tomei's first step toward research proved crucial for the development of their own 4B11 products as it involved familiarizing and discovering the basic characteristics of Mitsubishi's new engine design. Another aspect of this research included a side-by-side comparison with its predecessor, the 4G63. This comparison was significant for the Tomei engineers as it provided further insight on how this engine is going to be modified and its potential capabilities. The first and most obvious change from the 4G63 to the new 4B11 was the rocker arm-type valvetrain being replaced with the 4B11's direct acting unit and the timing belt being replaced with a silent-chain setup. The MIvEC feature, which was only available on the intake side on the latest version of the 4G63, was now available on both intake and exhaust on the 4B11, offering a wider range in powerband while keeping eco-friendly with emissions was the general focus for Mitsubishi engineers when building the engine.

Bearings Adopted Onto Exhaust Side Cam Journals
Several devices equipped on this engine indicate that the engineers at Mitsubishi have paid particular emphasis on the 4B11's oiling system design. On the exhaust side camshaft, the No. 1 cam journal was equipped with bearings since it's furthest from the oil line. This bearing adaptation was implemented to increase reliability and decrease friction within the cam journals. Thicker oil lines were also installed to supply an increased amount of oil due to the existence of the MIvEC system.

Highly Efficient Cylinder Head Engineered For Low Emissions And Power
The cylinder design was well thought-out and engineered by Mitsubishi with balance in mind. The design included engineering an area where the piston top geometrically matches well with the combustion chamber design. By looking at the piston design, it doesn't resemble the conventional forced-induction profile, but looks to be designed to that of a low-emissions engine. The intake and exhaust ports have large-diameter ports for improved efficiency. The low-emissions-producing design was also made with the MIvEC feature in mind.