Imagine accelerating from a dead stop up to an average velocity approaching 5000 feet per minute and back down to a dead stop 125 times every second. Now, imagine doing this in an environment seeing combustion gases in excess of 1400 degrees. Sounds like Hell and that's exactly what each piston in your engine must endure when you are buzzing at 8000 rpm. It's no wonder that pistons are considered one of the most critical components in an internal combustion engine.

Factory pistons are made with keeping production costs as low as possible. As a result, the majority of pistons found in today's engines are of the cast variety. While technology has made these cast pistons better than offerings from past years, there is no comparison in the performance and reliability increase that can be delivered by a quality set of aftermarket forged pistons.

Five Ways to More Power
A high-performance aftermarket piston can increase performance in as many as five different ways. First, the forged performance piston can be made in a bigger bore as to increase the displacement of the engine. How much power will this deliver? As a rule of thumb, the percent increase in displacement will deliver an equal percent increase in torque and horsepower. Second, aftermarket performance pistons can be ordered in a higher compression ratio than the original piston. The higher compression ratio improves the thermal efficiency of the engine. This allows the engine to produce more power while reducing exhaust gas temperatures. For most applications, an increase of a full-point in compression ratio generally results in a four-percent increase in horsepower and torque. Third, aftermarket forged pistons when combined with a quality set of piston rings will generally deliver an improved ring seal. This improved ring seal means that the pressure stays in the cylinder instead of escaping to the crankcase. As a result, the engine once again delivers more power and runs more efficiently. Fourth, a well-designed aftermarket performance piston will reduce free up some additional horsepower by reducing the friction in the cylinder. Many times, the forged pistons will use thinner ring sets and have a skirt profile which dramatically reduces cylinder to piston contact. Some manufacturers (like Mahle and HKS) take the technology even further and apply a dry-film lubricant to the piston skirts to minimize friction. Finally, since the material and manufacturing process used to make a forged piston are superior to cast pistons, weight can often times be removed from the piston. A lighter weight piston allows the engine to run more comfortably at higher rpms and makes it more responsive.\

Six Ways to More Reliability
In addition to providing at least five opportunities to improve power output, an aftermarket forged performance piston can also deliver six ways to improve strength and reliability. First, forged pistons are available in either a 4032 (low-silicon) or 2618 (zero-silicon) material. Both of these materials have superior physical characteristics compared to the aluminum alloy used in cast pistons. This means you are starting with a superior material. Second, an aftermarket performance forged piston can reposition the rings groves to lower the ring package away from the heat or increase the size of a ring land that's susceptible to damage from detonation. Third, through finite element analysis and computer modeling a piston manufacturer can redesign a pistons structure to provide the highest ratio of strength to weight. Fourth, along these same lines a performance piston manufacturer can increase the thickness of the material in critical areas like the crown and pin boss areas of the piston. Fifth, a piston manufacturer can apply a thermal barrier on the crown of the piston to limit heat transfer through the piston. Finally, the piston designer can employ bigger diameter or thicker wall piston pins to carry the high stress and strain of increased horsepower demands.

The Images Tell It All
Look at the precision machining that each forged performance piston undergoes at Ross Pistons. Ross was nice enough to supply us with some sample pistons at different stages of the machining process. The end products by Arias, CP Pistons, JE Pistons, Mahle and Ross tell the same story. Today's performance pistons are produced with some of the highest technology machinery on the planet. While different engine builders express a preference for a particular brand based on their experiences, every single aftermarket forged performance piston will outperform a factory cast offering.

For Boosted Only---The Battle of Boost versus Compression Ratio

Seven-hundred horsepower, 1.8-liter engines; 1200 horsepower, 2.1-liter four cylinders. Is this tomorrow's fantasy? No, it's today's reality. This reality includes the leading-edge forced induction and engine management technologies that make power production the easy part of building a racecar today.

In dealing with naturally-aspirated applications, high compression ratios are the key to serious power levels. In dealing with forced-induction applications, it's well known that increasing boost pressures of a properly sized turbocharger will increase power production (at least, to a point when the capacity of the turbo or fuel system is exceeded). Of course, the big downside to higher boost pressures is that the likelihood of encountering engine-damaging detonation also increases.

Next