JE Subaru EJ25 Ultra Series Forged Piston Set

4x EJ25 Ultra Series Piston

Ultra Series pistons are brimming with premium features and proven technologies that work in concert to provide racers with a winning formula.

The ceramic crown treatment is a spray-on coating that’s baked on to the piston. This coating reflects the heat of the combustion away from the piston, and that enables you to run at really, really high heat levels without the piston pulling in all the heat and softening. If we can keep the heat off the crown of the piston, it’s going to live significantly longer.

While the ceramic crown coating helps to manage heat, the lateral gas ports on the Ultra Series pistons help to achieve the best ring seal possible. Vertical gas ports have a tendency to get clogged and cause premature ring failure. A lateral gas port doesn’t apply the same amount of pressure but it’s a lot more pressure than you’d have without them, and your rings won’t wear out as quickly. It’s kind of the best of both worlds – excellent ring seal paired with longevity.

The accumulator grooves found on the Ultra Series pistons (and elsewhere in the JE lineup) are essentially notches in the material between the top and second ring to reduce pressure build up. Because of the added volume, the pressure caused by any gases that pass by the top ring are reduced, and that prevents the top ring from being unseated. It’s a nice machine feature that we’ve being using for a while now to get additional ring seal.

The Ultra Series also features JE’s Perfect Skirt technology, a coating which conforms to the bore size, in turn allowing for much tighter clearances without cold piston slap while also reducing friction.

While the Ultra Series pistons pack no shortage of high-end features, it’s the unique forging process that’s used exclusively on this line which is perhaps the most interesting element of their design, a breakthrough technology that strengthens the piston at the material level.

A new process that enables us to have 100% of the grains completely aligned with the shape of the forging.

Like wood, metal has a grain to it, and you want the forces applied to that material to be aligned with the grain rather than against it. Using a proprietary forging process called Aligned Grain Flow Technology, JE engineers are now able to precisely control metal grain direction around key structural elements of the piston. This process yields significant strength improvements, and an exceptionally robust part overall.

Perfect for Turbo or Supercharged as well as Race Engines!

(361328)

SUBARU EJ257 ULTRA SERIES
Ultra Series Includes:

Grain Flow Optimized Forging
Lateral Gas Ports
Ceramic Crown Coating
Perfect Skirt Coating
Accumulator Groove
Double Broach Pin Oiling
Upgraded 9310 Pins and locks
Carbon Steel Nitride Rings

SKU 361328
Brand JE Pistons

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