What makes an Evo an Evo? The short answer is threefold - rally car inspired handling, turbocharged inline 4, and full time all-wheel-drive. Let's get one thing straight - the Evolution is not a base model Lancer with a bunch of bolt on tuner parts. Just about every aspect of the vehicle was designed for performance, forged in the heat of WRC competition.
The heart of every generation since the Lancer Evolution I in 1992 is the famous turbocharged 2.0L inline four cylinder 4G63. This engine was actually available earlier in the first generation Eclipse/Eagle Talon/Plymouth Laser from 1990 to 1994, and from 1995 to 1999 in the second generation of the same vehicles. Generally regarded as bulletproof, the 4G63 has had a simple recipe for power - 1) big turbo + 2) big injectors + 3) magic black box. Retaining a completely stock bottom end, enthusiasts have been able to make upwards of 400 flywheel horsepower on a day to day basis.
The engine has evolved with the rest of the car, and it?s newest incarnation in the Evo 8 sports 8:8 to 1 compression cast aluminum pistons, a forged steel crankshaft, forged steel connecting rods, and a heavily reinforced block to withstand the stress of forced induction. The high flow cylinder head is equipped with sodium filled exhaust valves for decreased retention of combustion temperatures while hollow camshafts and lightweight aluminum retainers make for reduced rotational mass. A twin scroll TD05HRA-16G6-9.8T (try saying that three times real quick) turbo efficiently pressurizes the cylinders via a dual chambered turbine housing.
Generating this much output (heat and power) from this much pressure on a relatively small motor will create a detonation prone environment. To combat this condition, the Evolution is equipped with a relatively large front mount intercooler to remove heat from the intake charge. In 2003 models, the intercooler comes standard with a water sprayer designed to spray a fine mist directly onto the fins to further increase the cooling/condensing effect.
This combination in real world driving does produce a consistent powerband at speed as the close ration tranny keeps the motor in it?s powerband. Drop out of that powerband, and you?ll be crossing your fingers waiting for the turbine to spool up again. At low RPMs in first gear, the motor takes a inordinate amount of time to wake up. If you engage the gearbox without first bringing up the revs, you?ll be rewarded with a torque-free experience that even most Honda Civics will surpass (at least for a second or two). Once you hit the maximum boost of 19psi, the motor will pull to about 6000 RPM where boost will drop and you?ll fall flat on your face until you shift into the next gear. Opening up the exhaust and installing an aftermarket boost controller will cure this problem and allow turbo to hold full boost well into redline.
One of the best parts about driving a 4G63 at the limit is the sound. Driving through tunnels at wide open throttle, the roar of the exhaust coupled with the whine of the turbo and the hiss of the compressor bypass valve releasing boost between shifts is a unique aural experience. Too bad you don?t get this with the Evo, at least not out of the box. The turbocharger?s sound is muted and the exhaust tone is understated. Looking at the factory exhaust system, you can see the rear piping entering at 90 degrees into a variably valved muffler, which is good for noise surpression but bad if you really want to hear things. This is another nagging problem that will be fixed when we nix the factory exhaust system.
A big improvement on the transmissions of the first and second generation Eclipse, the Evo?s tranny is a five speed reinforced affair. The first two gears are equipped with triple synchros, dual synchros in third, and single synchros in fourth and fifth gears. Coupled with a short throw counter weighted shifter, gear selection is a smooth and precise operation. Power is fed through the transmission into a viscous coupling that divides torque evenly between the front and rear wheels. Power distribution between the forward left and right wheels is controlled via an open differential while the rears are split with a mechanical plate style limited slip differential. The factory clutch is a 240mm unit coupled with a lightweight flywheel. This provides for relatively smooth engagement and a fast revving motor, but is a setup that won?t last long under abusive driving (i.e. drag racing style AWD launches).
Stay tuned for our next segment when we?ll explore the third part of the Evolution equation - the chassis.