JE Pistons: Inside Look at HP Heavyweights

A company crowned piston perfect explains its craft and weighs in on why the Hayabusa's powerplant is still unmatched.

From the June, 2012 issue of Super Streetbike

By Sean Russell

Photography by JE Pistons, Staff

Putting power to the pavement is a complex symphony of motor mechanics. If one component fails the entire shebang goes south faster than a toothless lady of the night, but when things work, magic happens. More often than not, JE Pistons has played a part in that big power magic. We caught up with these piston kings to hear an insider’s take on who provides the best platform for monster numbers and what it takes to get there.

Pistons worthy of a world record machine are not an instant affair. Getting the right parts at the Stotz Racing level takes years of dragstrip testing , evaluation and development.

No other sportbike has proven more capable of producing staggering dyno numbers than the Hayabusa. Streetable Hayabusas have spun the drum to the tune of 700+ HP in recent years. When Kawasaki’s latest modern marvel hit the scene the ‘Busa was beat-down by the press for antiquated technology. Stock to stock, SSB even crowned the ZX-14R a more capable streetbike. But what about the aftermarket? Pushing emotions to the side in the hypercruiser debate is easy for a piston company. Brand name means squat if the mechanical makeup isn’t right. Since 1999, JE Pistons has entrenched themselves in developing ‘Busa pistons, rings and pins that today can support over 1,000 HP—good luck attaining those kind of numbers.

“We have sold more Hayabusa pistons than any other piston company on the planet. We were the first to market and have basically carried that all the way through,” said Brian Weaver, JE Pistons’ Powersports Manager.

Nitrous was the weapon of choice in the late nineties. Spraying extra HP gave way to forced induction and the “big number” builders worked for crept up from 250 HP to 350 HP and well beyond. At the heart of the race for more power is a volatile relationship between combustion and the pressure it places on cylinder components. Before building a beast it’s important to know what you’re up against.

Pistons Under Pressure

Sitting front and center to each power-producing explosion are the pistons. As HP numbers climb so does the heat in the combustion chamber. Stock components will literally fold under the pressure. “Pro Street guys like Kent Stotz pulling six-second runs on a 1000 engine are running purpose-built pistons because the standard piston, compression height, pins, and all that will not withstand what is being thrown at it to achieve those milestones,” said Brian.

Running boost and spraying nitrous turns up the heat and inevitably roasts internal components that aren’t equipped to handle it. According to JE Pistons, pre-ignition starts after 1,600 degrees Fahrenheit but aluminum parts start softening well before that. “Pistons get soft a couple hundred degrees under 1,600 degrees. Once soft it becomes very malleable and starts flexing, which causes your ring grooves to go all over the place. As it continues to flex you can umbrella the whole part and that is where cracking occurs. From there it just becomes total destruction,” explained Nick DiBlasi, JE Pistons’ Product Manager. “How well you support the piston and how well it’s built will determine if it can withstand all the heat and pressure. Internal and external bracing is a huge thing for a stable part.”

The 2618 Aluminum Alloy used in all of JE’s motorcycle applications is stress-tested to the point of excess. A long partnership between Stotz Racing and JE helped develop a piston later used in the record breaking CBR1000RR, “We have not had a piston failure in three years now. At the start of the 1000 project we had serious scuffing on the front and back of the piston skirt at high boost. JE kept inspecting the piston and changing the piston’s cam (shape) and then had me tighten up the piston to wall clearance until we had it right,” said Kent Stotz.

It’s obvious getting a big number isn’t possible without big pistons. So what motor for the up and coming power punk has the greatest potential?

Hayabusa vs. ZX-14R

Think straight-line speed and two bikes should come to mind. The Suzuki had a seven-year head start, which has amounted to a serious supply of used motors floating around for cheap and a massive aftermarket catalogue. Since the start, JE Pistons exploited the hypercruiser’s powerplant and can confidently say it’s the most versatile option when seeking serious power.

Brian explains,“The Hayabusa’s removable cylinder is quick to exchange, rebore or repair if damaged. In 2004, turbo chargers had improved and boost had increased so we improved piston strength by increasing the deck height of the piston. The removable cylinder aided the design by allowing a spacer plate to slide under the cylinder. We were the first in the Hayabusa turbo market with tall deck pistons. The taller piston allowed us to thicken up the ring lands to keep them from collapsing under high boost pressures.

Brian then laid out why Kawasaki has had problems stealing market share.“Throwing big boost on this engine proved to be a bigger challenge. Being a monoblock presents some challenges in boring, replating and increasing the compression height on the piston. To achieve big HP, shorter rods are needed to add land thickness to increase piston durability. Though a good engine, it lacks the versatility of the Hayabusa’s removable cylinder.”

Conclusion

Achieving wild HP is a risky and expensive game. It is the sum of many parts working together. Those who don’t want to reinvent the wheel are safe with Suzuki, period. The ZX-14R hasn’t accumulated the followers, aftermarket options and used part market scope as the Hayabusa, although things may change in the future. As of today, the most flexible and budget friendly engine for copious HP is that of the Hayabusa—sorry Team Green. ssb

Piston Breakdown

A PhD in mechanical engineering is required to understand piston science but these key terms will get you started.

Crown: The top of the piston where the combustion occurs.

Skirt: Sides of the piston that act as stabilizers. Skirts also help scavenge heat away from the combustion chamber and crown and down the sides of the piston.

Ring lands: The area of the skirt between the rings. 70% of heat is transfered through the rings to the cylinder walls.

Wrist Pin: Secures the small end of the rod to the piston.

Connecting Rod: Links the piston to the crank and transfers up-and-down motion from the piston into spinning motion at the crank.

Piston Rings: Creates a gas-tight seal between the circumference of a piston and the cylinder wall to guarantee the force from combustion doesn’t escape around the piston.

Crankshaft: Turns the up-and-down motion of the piston to rotary motion used at the rear wheel.

Bore: Diameter of the cylinder opening; the bigger the bore the bigger the displacement. Bore x stroke = motor displacement.

Stroke: Distance between the two end points that the piston travels inside the cylinder. The longer the stroke the larger the displacement.