If you haven't figured it out yet, power is evil. Once you get a taste of it, you always end up wanting more. After we performed the first battery of performance upgrades on our EVO VIII, we were hooked. We pushed the output of the Evolution by 44.4 hp, peaking at 292.4 with four bolt-on upgrades. Impressively, the increased output was done at the stock boost pressure. By using higher flowing performance parts and fine-tuning the fuel and ignition maps via AEM's EMS, we increased the Mitsubishi's output from the stock 248.0 to 292.4 hp.
To ensure the car was still up to spec, we re-baselined the Evolution on XS Engineering's four-wheel-drive DTS chassis dyno after a couple of heavy right-foot actions. It baselined at 291.0 hp-pretty much consistent with the previous session. The 1.4-hp decrease could have resulted from a change in weather conditions or from strapping the vehicle on the dyno. It's always important to perform a new baseline to kind of reset the clock. This ensures the parts previously installed are still making power and provides a new "ground zero" for future upgrades.
For this round we opted to further improve the exhaust flow characteristics by adding a tubular, stainless-steel turbo manifold from DC Sports. The manifold we tested was a prototype piece, but by the time this issue hits the presses, it should be available to the masses.
The factory turbocharger features a twin-scroll design similar to those used on the 4G63 Eclipse GSX and GS-T turbos. The factory Evolution turbocharger has two inlet ports in the turbine housing. The twin-scroll turbocharger only works with a turbo manifold designed for this configuration. The factory cast manifold links the number one and four exhaust ports and the two and three exhaust ports together. Each pair converges to feed each side on the turbocharger inlet simultaneously based on the engine's firing order.
Often the factory components are designed with cost in mind. In doing so, the stock turbo manifold isn't very free-flowing and has several harsh angles restricting flow. DC Sport's tubular, stainless-steel turbo manifold follows the same general characteristics of the stock manifold but is designed for better flow.
Unlike the cast manifold, the DC Sports piece utilizes smooth radius stainless-steel tubing to expedite exhaust flow from the exhaust ports of the cylinder head into the turbocharger. Like the stock manifold, the DC Sports manifold links cylinders two and three, and one and four. The manifold features stainless flanges that are CNC-machined and the entire manifold is TIG-welded. The DC Sports piece also keeps the turbocharger in the exact same location as the stock manifold, so there's no need to change any components you're currently using.
Installing the manifold is a straight R&R affair. The swap can be performed in a couple of hours with simple hand tools. With some finessing we removed the manifold without removing the turbocharger. Once installed, the manifold adds some eye candy underneath the hood. As with any stainless-steel exhaust piece, wipe down the manifold with brake cleaner before starting the vehicle to avoid unsightly blemishes.
On the dyno the DC Sports turbo manifold truly shined, generating an additional 10.9 hp and 4.2 lb-ft of torque to the wheels. Since we data-logged the boost pressure, we determined the boost levels were actually lower with the DC manifold than the stock counterpart. With the manifold boost, pressure peaked at 219.6kPA (17.58 psi); the stock manifold peaked at 222.8kPA (18.05 psi), about 0.5 psi more than the DC manifold.
One reason for the stock manifold's higher peak boost pressure is the thermal mass of the cast-iron manifold. Due to the improved flow of the DC Sports piece, the engine loses less power trying to push the exhaust gases through the manifold, in turn generating more power.
For the second performance upgrade we added five gallons of 104-octane VP Racing unleaded racing gas. High-octane gas is extremely important when fine-tuning the ignition and fuel maps for maximum output. Ninety-one-octane juice lacks stability under boost pressure. By using higher-octane fuel we can run more timing and run a slightly leaner fuel mixture for maximum horsepower output.
Greg Nakano of AEM worked his magic on the laptop, and we were able to generate an additional 14.2 hp and 11.9 lb-ft of torque by just adding the high-octane fuel. We spent about $8 per gallon on the VP Racing gas, but for $40 the five gallons generated 14-plus hp. Pretty good horsepower-to-dollar-spent ratio.
In the end we were able to squeeze another 24.2 hp and 16.1 lb-ft of torque from two go-fast goodies.
For the next installment we are looking to add larger injectors, performance camshafts from Buddy Club and possibly a larger front-mount intercooler. This is just the beginning of the Evolutionary process.