Additional Air In + Less Restriction Out = Power Gains.
Breathe Easy
As I'm sure you've heard before, the internal combustion engine is nothing more than an air pump-the more air the pump can process/move, the more power it can make. While this basic theory holds water, other contributing factors are to be considered, such as engine displacement, camshaft profile, valve size, and so on.
In many cases, the first, easiest and most cost-effective modification performed to a virgin automobile in order to produce power gains is the air filter/induction system. With a plethora of options in the aftermarket, a single air filter or cold-air induction system can net decent power gains, but is it due to the higher rate of airflow into the engine? Some may argue yes, and some no-the larger amount of air into the engine helps, but in some cases the vehicle's electronic control properties are centered on the stock filtration system.
By changing to a higher-flowing unit, the air-fuel mixture is essentially leaned out, causing an increase in power (leaner is meaner). Most vehicles are tuned conservatively from the factory, so leaning the mixture out doesn't generally cause an engine-damaging condition. But be aware of what you're doing.
At the other end of the spectrum, what goes in must come out, which leads us to the exhaust system. Spent exhaust gases are expelled from the engine via the exhaust valves, through the exhaust ports in the cylinder heads, then the exhaust manifolds/headers, one or more catalytic converters, several bends in the exhaust tubing, the mufflers-finally reaching the atmosphere via the tailpipe(s).
That leaves us with many avenues for restrictions. Engineered restrictions are necessary to produce a certain amount of backpressure, although some think manufacturers add additional restrictions to detune the car.
Before getting started, Doug strapped the C6 to ECS's mobile Dynojet dynamometer for some before numbers. The LS2-powered Corvette put down 324.4 hp and 321.8 lb-ft of torque to the rear tire. With these cars being rated at 400 hp from the factory, wheel horse seemed dead on with an approximate 20 percent loss through the drivetrain. The factory exhaust system is definitely a decent piece, but who among us can leave well enough alone?
But keep in mind that your favorite car company has to meet stringent noise restrictions (both corporate and government mandated), safety and fuel economy standards, and emissions regulations. As hot rodders, we look at all of the potential power gains achieved by applying aftermarket components to reduce the factory road blocks in your engine.
Additional factors that will increase the "in and out" effect are throttle plate/body size, intake manifold port diameter and runner length, camshaft lift and duration, intake and exhaust valve sizes and cylinder head port volumes. When taking an engine to the extreme via extensive modifications, it is necessary to consider additional factors such as injector size and custom tuning to the engine management system, which can become very costly, never mind turning your ride into a gas-guzzling beast that won't pass an emissions test and who knows about the drivability thereafter.
For this particular installation/test we'll leave the actual engine alone, installing an air-induction system from Motorsport Technologies in Houston; long tube headers and mid-pipe with catalysts from American Racing Headers in Amityville, New York; and a trick-looking quad-tipped muffler system from GHL Motorsports in Mesa, Arizona.
The specimen being utilized is none other than an LS2-powered 2006 C6 Corvette automatic with paddle shifters. To perform the installation duties and custom tuning, we called upon Chris Corriell, Doug Ring and the crew of East Coast Supercharging in Cream Ridge, New Jersey. ECS specializes in LSX-powered vehicles, especially the Corvette, so we were more than comfortable being surrounded by the professional staff, as well as the stout machinery being modified at its facility.