Ever try blowing through a tiny cocktail straw, not that I've tried, but hypothetically speaking? For the amount of effort you exert you don't get much in return. It would be much easier if the diameter of the straw were bigger. While you're wondering what a straw has to do with a Mitsubishi Evolution, trust us it's more relevant than you might think. One of the areas most Evolution enthusiasts often overlook is adding performance camshafts to their 4G63.
For obvious reasons the factory Evolution camshafts were not designed for maximum horsepower. Smog regulations and idle quality often dictate their measurements. The result often means a lower lift camshaft with less duration. Lift refers to how far the valve opens while duration refers to how long the valve stays open. This is where the straw reference comes into play.
Hypothetically speaking, let's say the factory Evolution camshafts have 7mm of lift with 248 degrees of duration. From the point the valve begin to open to until it fully closes will take 248 degree of the camshaft's rotation and will attain 7mm of full lift. However, if you had a camshaft with higher lift and longer duration, theoretically, it should be easier for compressed air from the turbocharger to make its way into the combustion chamber.
Known for its Honda camshafts, Buddy Club also offers bumpsticks for 4G63 and SR20DET engines. These camshafts are advertised as having 264 degrees of duration and 10.8mm of lift. Made from billet cores the BC cams are specially designed to increase the turbo engine's efficiency by allowing more air to reach the combustion chamber. This in turn enables the engine to generate more power when mixed with additional fuel. Each BC camshaft comes specially coated with a thin layer of dry lubricant allowing for proper break-in during initial start up.
For maximum power output the camshafts need to be degreed in using a degree wheel and adjustable cam gears. We opted for a pair of billet AEM Tru-Time adjustable cam gears. With the camshafts degreed we made a baseline run on XS Engineering's DTS dyno and got back 302.5 horsepower.
However, as mentioned earlier, in order to extract maximum power fuel enrichment is necessary. With Greg Nakano from AEM on the laptop data logging every run, he was able to recalibrate the fuel mixture for more power. The retune was good for another 10.9 horsepower, bringing peak power to 313.4. The BC cams and the retune generated a total of 11.5 horsepower more than the factory camshafts.
Surprisingly we were still able to attain a fairly stock-like idle with the longer duration and higher lift BC cams. From 3000 rpm to redline the BC cams generated more power than the stock cams. Peak torque numbers also rose by 4.0 lb-ft with a maximum torque of 266.4 lb-ft at 6400 rpm. Torque figures rose as high as 12 lb-ft over stock at areas of the power curve.
With nearly 400 horsepower to the flywheel we were running the injectors at the ragged edge. The factory 540cc injectors were nearly at 100 percent duty cycle at the top end. To ensure the Evo's thirst is always quenched we went big. At almost two times the size of the factory 540cc squirters, the MSD 96lb (1008cc) injectors are massive. The MSD injectors did require some machining in order to fit them into the factory fuel rail. Any competent machine shop should be able to perform this job. We had ours done at XS Engineering for about $100.
With the injectors in place Greg recalibrated the AEM EMS system for the larger injectors. This time around the injectors were only running at 45 percent duty cycle at full load; much safer than before.
To our surprise the MSD injectors also generated a little more power over the stock injectors. Our guess is the MSD injectors have a better spray pattern than the stock injectors allowing for better atomization of the fuel. Whatever it was the MSD injectors posted a 4.1 horsepower increase over the stockers, pushing peak power to 317.5 horsepower at the wheels.
In our December 2005 issue we were the first to feature the Blitz i-Color boost controller and now we are the first to test it out on the dyno. Previously we had been using the factory boost controller to maintain boost pressure but with the solenoid maxed out on the EMS computer we were only able to generate 1.196 kPA (17.58 psi) of boost pressure.
The i-Color is not just about glitz and glamour, the controller utilizes an extremely effective twin solenoid design for boost control. After dialing in the i-Color for increased boost we generated 1.463 kPA (21.51 psi) of boost pressure. With the increased boost we were able to generate 345.2 horsepower to the wheels on 91-octane pump gas. Gains as high as 30 horsepower were vividly illustrated on the dyno graph.
Considering we only increased boost pressure by 4 psi the power increase was substantial. In addition to the previous installment we increased the output of the Evo by 42.3 horsepower to the wheels. Compared to a stock Evolution we nearly generated an extra 100 horsepower and we have yet to open up the engine.
What's next you ask. We are itching to try out a larger pair of camshafts as well as a larger bolt-on turbo or complete upgrade. However, before we even address more bolt-on performance adders we must address the factory fuel pump and ignition system. So until next time we will keep turning those wrenches.