What do the EVO-VIII, WRX, and GT-R all have in common? All three of these platforms rely on an all-wheel-drive configuration to deliver phenomenal street performance. Unlike a two-wheel-drive vehicle that only uses two contact patches for acceleration; an all-wheel-drive vehicle has the advantage of using all four tire contact patches to propel the vehicle forward. As a result, all-wheel-drive vehicles are more capable of putting the power to the pavement. Putting the power to the pavement was the exact intent of Jimmy Jennings when he purchased this 2003 EVO VIII. Thanks to the wrenches at RnR of El Cajon, California, this Mitsubishi lays down 620 horsepower on race gas and over 450 horsepower with on a diet of decaffeinated 91-octane.

Balance: Response & Power

When building a turbocharged performance vehicle, the tuner must always strike a balance between response and power. While gigantic turbochargers are necessary for giant power figures, throttle response and the amount of useable powerband can be compromised. When we fitted our stock GT-R RB26DETT engine with a pair of turbochargers capable of generating 1000 flywheel horsepower, the entire personality of the engine changed. With the factory turbochargers in place, the engine starting pulling from 4000 rpm; then it paced itself to redline. With the BIG turbos in place, the engine was lazy until about 6300 rpm. From 6300 rpm to 9000 rpm, the engine pulled as if someone had activated a 200-shot of nitrous oxide. Our combination made the horsepower figures, but it wasn't that fun to drive due to its narrow powerband and lazy response.

To avoid this situation with this Mitsubishi, a target horsepower goal needed to be set first. Jimmy's desire was for a combination that could produce in excess of 600 horsepower on race gas and over 450 horsepower on 91-octane pump gas. These criteria led RnR to choose a GT35 turbocharger. The GT35 turbocharger features some of the latest-generation turbocharger technologies and its flow potential was perfect for the horsepower goals. However, the GT35 is still a "big" turbo that will definitely be lazy on a stock engine. Hence, the decision was made to build the engine with an emphasis on improving response.

Stroked, Poked, Ported, and Prepped

There are a number of factors that can influence how a turbo responds on a particular engine. These factors include engine size, camshaft profiles, exhaust manifold design and fuel/ignition tuning. All other factors being equal, a larger engine will provide a greater supply of exhaust energy to drive the turbine section of the turbocharger. Quite simply, a 2.4-liter engine will be able to spool the turbo to the desired boost level about 20 percent sooner than a 2.0-liter. If a 2.0-liter engine reaches "full boost" by 5000rpm with a particular turbo, a 2.4-liter engine will reach "full boost" at about 4150rpm. Since the 4G64 crankshaft measures 100mm, instead of 88mm (the original stroke of the 4G63), the displacement of the 4G64 engine is considerably larger. On the negative side, the long stroke of the 4G64 does limit rpm potential. Even with the best available bottom end components, exceeding 8000 rpm is not recommended on 4G64s, as average piston speeds are already buzzing at 5200 feet per minute at that rpm. Under 8000 rpm, the 9-to-1 forged pistons and Eagle connecting rods have no problem staying together.

While additional displacement helps to bring the boost in sooner, RnR also decided to capitalize on optimizing the cylinder head flow, camshaft profiles, exhaust manifold design and fuel/ignition tuning to maximize response. An RnR sheet-metal intake manifold and 65mm throttle body were called upon to direct airflow into the cylinder head. The original cylinder head was worked over with a set of Ferrea 1mm-oversize valves and Tomei valve springs. A pair of HKS 272 bumpsticks were selected to control the valve events. When valve events call for the exhaust to flow out of the cylinder, an RnR equal-length "ram-horn", tubular exhaust manifold directs high-enthalpy exhaust gases into the turbine inlet of the GT35 turbo. Of course, performance is never optimized unless the fuel and ignition delivery is tuned for maximum performance.

To provide the correct amount of fuel, a Walbro in-tank 255lph fuel pump pushes the gasoline up to the quartet of 1000 cc/min injectors. These injectors take cues from the AEM EMS engine management system. The AEM EMS also triggers the AEM C2DI digital, multi-channel ignition amplifier. This amplifier powers the coil-on-plug ignition that provides the high voltage for the NGK BP7ES plugs.

The end result of this combination is a setup that matches the factory torque output at 3500 (286 lb-ft); provides a peak torque that's more than double the factory figure at 4900rpm (590 ft-lb); and delivers a wheel horsepower that's over two-and-a-half times the factory horsepower output. A tank full of C16 and a twist of the boost controller up to 30psi is all that's needed to bring out the Mr. Hyde in this Dr. Jekyll.

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