Sleek styling at a competitive price, the EVO IX has carried the Mitsubishi name to new heights for 2006. Producing an impressive 274hp and 295 lb-ft of torque through a 2.0-liter MIVEC power plant, this beast from the east delivers a spellbinding 12-second quarter-mile time while delivering incomparable handling. Slated as the next generation of super cars in the import market, horsepower hungry individuals have taken these all-wheel-drive monsters to the next level, snatching up every conceivable product sold over the counter with high hopes and expectations of breaking the 400whp barrier. Unfortunately, many EVO owners fail to recognize a potential ticking time bomb, waiting to erupt with every bolt-on piece.
With import cars, such as the EVO producing more horsepower than ever before straight from the dealer, upgrading with the correct injectors becomes critical in maximizing horsepower and engine efficiency. RC Engineering of Gardena, Calif., has recently released two off the shelf injectors that tend to the woeful mishaps of running the engine lean. RC, fuel injection specialist for more than two decades, has developed both 750cc and 1000cc drop-in njectors as a simple and effective way to ensure consistent fuel is flowing through your 4G63 engine.
What injector is right for my application you ask? Selecting the correct injector can be a tricky process. The most common mistake among automotive enthusiasts is "bigger is better" in terms of fuel delivery. RC Engineering's research states that unless the airflow in an engine has been increased 20 to 25 percent over stock, larger injectors are generally not needed on a streetcar. It has been proven that properly operating stock fuel injectors have the potential to supply fuel for another 10-15 percent more horsepower over stock. "We've had numerous customers calling to purchase a set of our newer 1000cc injectors. Obviously they're looking for maximum flow for their 400hp EVO but they seem to only focus on what's at hand. They often don't consider that these injectors might be too big for their application and often won't function properly without some sort of aftermarket fuel management or ECU modification," states RC Engineering's John Park. Always keep in mind, bigger isn't always better
Proper Injection selectionTo find out the approximate injector size to run, use the following formula to select the correct size injectors in lb/hr for your application. As a sample, we'll take a modified Mitsubishi EVO rated at 380hp to the crankshaft.
First, we need to determine the Brake Specific Fuel Consumption (B.S.F.C). B.S.F.C equals how much fuel an engine needs to make X amount of power. The lower the number, the more efficient it is. The B.S.F.C varies, depending if the car is naturally aspirated of turbocharged. For NA cars, the B.S.F.C. will be anywhere from .45 to .50. This means the engine will use .50 lbs. of fuel per hour for each horsepower it produces. For turbocharged engines, the scale will be at .55 to .60 lb/hr or higher depending on whether the engine is running on pump gas or race fuel. If the car is running race fuel, the BSFC is slightly lower.
Take the target horsepower at the crankshaft (380) and multiply that number by the B.S.F.C (.60) = 228.
Take the number of injectors (4) multiplied by the injector duty cycle (.80) = 3.2
Finally divide the 228 by 3.2 (= 71.25 lb/hr), which is the total per injector.
To convert from lb/hr to cc/min, take 71.25 and multiply by a factor of (10.50) = 748cc/min.
The proper injector size for this application would be 71 lb/hr or 748 cc/min.
Spray patternsCompare the factory EVO injectors spray patterns to that of an aftermarket race injector, and the results are blatantly obvious. Stock injectors are developed by manufactures to finely atomize in order to promote a clean-burning vehicle while maintaining maximum fuel efficiency. These same injectors are engineered to pass regulated tailpipe emissions tests, but aren't the particular injector you want when looking to produce maximum horsepower. Race cars prefer a tightly coalesced spray pattern, or one that shoots fuel in a narrow stream to keep the fuel flowing at high velocity. At high RPM, it's a fact you don't need or want an injector that mists-you need one that can spray plenty of fuel into the combustion chamber.