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EVO X engine details
EVO X engine details
Guys & girls I found this article about the EVO X engine.
I would love to know the tuning potential of the new 4B11 engine. The section at the bottom of this article 'Last Minute Additions' makes interesting reading. It implies that the new 4B11 has a forged crank and forged connecting rods. Can anyone confirm if this is true? Does this mean that higher boost levels can be achieved on the standard engine?
The 4B11, like the 4G63 it replaces, is an intercooled-turbocharged 2.0-liter DOHC inline four-cylinder; beyond that description, the two engines are vastly different. The 4B11 is built with a cast-aluminum cylinder block versus the cast-iron block used in the 4G63. That change, among others, helps reduce overall engine weight by 27.5 lbs. compared to the iron-block 4G63, even with the addition of a timing chain replacing a belt and MIVEC variable valve timing on both the intake and exhaust camshafts (the 4G63 had MIVEC on the intake only). A revised turbocharger yields up to 20-percent quicker response at lower engine speeds.
The new 4B11 T/C produces more power than its predecessor: 291 hp at 6,500 rpm (vs. 286 hp at 6,500 rpm) and 300 lb.-ft of peak torque at 4,400 rpm (vs. 289 lb.-ft. at 3,500 rpm). It is important to note, too, that the 4B11 offers a broader torque curve, producing a bit more torque than the 4G63 at all engine speeds, and also offering a torque "bubble" from 3,500-4,500 rpm, where the 4G63 begins to fall off.
High-Strength Aluminum Construction
Although based on the same architecture as the 4B11 naturally aspirated engine, the 4B11 T/C engine in the 2008 Lancer Evolution starts with a unique block casting and is reinforced for turbocharging. A semi-closed deck structure and an integrated ladder frame contribute to the strength, as do four-bolt main bearing caps. The die-cast ladder frame also helps reduce noise, vibration and harshness (NVH) levels. Unlike the 4G63, the 4B11 does not use a balancer shaft.
The new 2.0-liter (1,997 cc) engine's bore and stroke both measure 86.0 mm (3.4 in.), making it a "square" design with a bore-stroke ratio of 1.0. In comparison, the 2.0-liter (1,998 cc) 4G63 was slightly "over-square," with an 85.0 mm bore (3.34 in.) and 88.0 mm stroke (3.46 in.) for a bore-stroke ratio of 1.04. The semi-floating pistons of the 4G63 have been replaced with a fully floating pistons for the 4B11, which improves reliability while reducing frictional loss. Compression ratio is slightly higher in the 4B11 - 9.0 vs. 8.8 for the 4G63.
The red zone on the tachometer starts at 7,000 rpm, with a fuel cutout at 7,600 rpm to protect the engine. Using a timing chain instead of a belt allows for a more compact design and also helps ensure reliability. Iridium spark plugs contribute to lower emissions and help extend major service intervals. Premium-grade (91 AKI) fuel is required. The 2008 Lancer Evolution is certified to the LEV II / Tier 2, Bin 5 emissions standard.
The stainless steel exhaust manifold has a rear location on the transverse engine, compared to the front location for the previous engine, yielding important benefits. The new location helps improve weight distribution and is one factor in the new Lancer Evolution having 4 percent less load over the front wheels (GSR) than the previous model. The rear location makes it easier to package the catalysts for quicker "light off," and therefore better emissions performance. Also, as detailed in the "Chassis" section of this press kit, the manifold's rear location allows the use of a flat front suspension crossmember, which is stronger than the previous saddle-shaped crossmember needed to clear the exhaust pipe.
Aluminum is also used for the timing chain case and cylinder head cover, the latter being resin in the normally aspirated 4B11 in other Lancer models). A revised breather nipple location dramatically reduces the amount of oil blow-by.
The 4B11 is a more compact engine than the 4G63. In cross section, minus the rear-mounted exhaust manifold, it is 5.3 inches narrower, allowing more crush space in front and behind it for enhanced collision safety.
Engine Technology Overview and Benefits
Technology Performance and Fuel Consumption Compact & Light Low Emissions Low NVH Durability
Diecast aluminum cylinder block
4-bolt main bearing caps
Semi-closed deck block
Direct-acting DOHC valvetrain
Timing chain (vs. belt)
Serpentine belt accessory drive
Isometric short port aluminum intake manifold
Exhaust manifold at rear of engine
5W-30 engine oil
Compact, large-volume atomizing fuel injectors
No balancer shaft
Water pump with rubber impeller integrated with shroud
Iridium spark plugs
Long-reach M12 spark plugs
Electronically controlled throttle
New Direct-Acting Valvetrain
The double overhead-cam (DOHC) 16-valve cylinder head is also aluminum, and the greatest divergence from the previous architecture is in the use of a direct-acting valvetrain in place of the roller rocker arm configuration for reduced weight. A direct-acting valvetrain also yields a more compact layout. The reduction in number of parts alone reduces weight, as does using built-up (hollow) camshafts and eliminating the rocker arm assembly, including lash adjusters, and adopting valve stem seals integrated with the spring seats. A weight reduction at the top end of the engine also contributes to a lower center of gravity.
Valvetrain friction has also been reduced through the use of additional phosphoric acid coating treatment on the camshafts, reduced valve spring weight (see table), reduced frictional resistance and additional polishing of valve stems.
Valve Specifications 2008 Evolution 4B11 T/C Evolution IX 4G63 T/C
Valve narrow angle (deg.) 47 57
Intake valve diameter (mm) 33.6 33.0
Exhaust valve diameter (mm) 27 29.5
Valve stem diameter (mm) 5.5 6.6
Mitsubishi Innovative Valve Timing and lift Electronic Control (MIVEC)
The Mitsubishi Innovative Valve Timing Electronic Control (MIVEC) - a continuously variable valve timing system - works on both the intake and exhaust valves versus just the intake side for the most recent version of the 4G63. The addition of MIVEC to the exhaust side helps ensures optimal power, high fuel efficiency and low emissions across the engine's operating range.
Variable valve timing systems optimize engine performance in response to operating conditions. In the Lancer Evolution's MIVEC system, intake and exhaust cam timing is independently controlled to provide four optimized engine-operating modes:
Under most conditions, to ensure highest fuel efficiency, valve overlap is increased to reduce pumping losses. The exhaust valve opening timing is retarded for higher expansion ratio, enhancing fuel economy.
When maximum power is demanded (high engine speed and load), intake valve closing timing is retarded to synchronize the intake air pulsations for larger air volume.
Under low-speed, high load, MIVEC ensures optimal torque delivery with the intake valve closing timing advanced to ensure sufficient air volume. At the same time, the exhaust valve opening timing is retarded to provide a higher expansion ratio and improved efficiency.
At idle, valve overlap is eliminated to stabilize combustion.
The 2008 Lancer Evolution uses a freer-breathing exhaust system than the previous model. The front pipe diameter is now 65.0 mm (2.6 in.), up from 60.5 mm (2.4 in.). The rear exhaust manifold location yields a shorter exhaust pipe, which is more efficient. Main muffler capacity is increased by 31 percent, from 16 liters in the previous model to 21 liters in the 2008 model. The larger muffler, along with the new twin-pipe outlet with elliptical tips, yields a deeper, more powerful sounding exhaust note. Unwanted noise, meanwhile, is mitigated by reducing the number of exhaust pipe hangers from five to four and by adding a spherical joint in front of the main muffler.
Metallurgy - LAST MINUTE ADDITIONS
The internal components of the new Lancer Evolution's engine have been reinforced to withstand high levels of boost. The turbocharged version of the new 4B11 features a cross-drilled forged steel crankshaft that rotates in 4-bolt main bearing caps. Also unique to this engine are reinforced forged steel connecting rods that are attached to pistons unique for the application. The new engine's pistons are gravity castings made of a high strength aluminum material designed for durability, and quiet operation, and also include a unique ring package optimized for this engine