Custom JE Pistons
Custom JE Pistons for Porsche EnginesLN Engineering has offered custom JE Pistons to rebuild your aircooled or watercooled Porsche engine since 2002. With thousands of custom piston designs, we likely have made the piston you are looking for. If not, we will work with you to design the best possible piston for your Porsche engine. This starts with our custom piston worksheet that allows us to collect all the information needed to build a custom piston. We then work out the details directly with JE Pistons so you don't need to worry about technical side of the custom piston process. Depending on your plans for the engine, we will make recommendations to you on available upgrades. In some cases, a custom piston is not required, but if we don't have what you need on the shelf, we'll happily make it for you custom for the same price as one of our off-the-shelf pistons.
Every custom JE Piston from LN Engineering includes these features standard:
Full CNC machining
Precision CNC machined ring grooves
2618 low silicon forging alloy (or 4032 high silicon material available on some applications)
Diamond turned skirts
Single forced pin oilers or broaches
Pick lock grooves for use with wire locks or carbon steel spiro locks
Machined side reliefs on full round forgings
Anti-friction coated piston skirts
What custom piston options are available?
Ultra Crown Dome Ultra Crown Inverted Dome: The Ultra Crown machining process allows incredibly precise dome to cylinder head tolerances. By mapping the exact shape of a piston or cylinder head, optimum compression and quench characteristics can be achieved.
3D Under Crown Milling: The Under Crown machining process allows for uniform deck thickness, therefore creating a lighter and more durable piston.
Vertical Gas Ports: Vertical holes in the deck of the piston, allows combustion pressure to directly enter behind the top ring on the power stroke, thus pressurizing the area behind the top ring for greater ring to cylinder wall seal. During the rest of the cycle, the ring has normal tension for reduced friction. (Most commonly used for drag race applications).
Lateral Gas Ports: This process mills slots into the top of the top ring groove and provides a pathway for combustion pressure to get behind the top ring. This process helps to increase ring seal and is most common in circle track applications.
Ultra Groove: Ultra Groove is a special ring groove machining process that provides near perfect groove flatness and surface finish. Tolerances are held to millionths of an inch.
Spin Boss & Window Milling: In certain applications window milling will remove a significant amount of weight from the skirt of the piston while maintaining its strength and integrity. Spin Boss refers to machining on the bottom of the pin boss, which removes weight where it is not needed for strength.
Plunge Boss & Chamfer Pin Boss: Machining process that removes additional material for added weight savings.
Contact Reduction Grooves: The purpose of machining these grooves is to reduce the amount of contact area against the cylinder wall when the piston “rocks over”. Contact reduction also serves to disrupt the flame travel into the crevice area thus helping to reduce detonation.
Accumulator Grooves: An accumulator groove is machined into the land between the top and second ring. It provides additional volume where residual combustion gases that have "blown by" the top ring can collect. This additional volume helps to reduce pressure between the top & second ring, thus aiding in top ring seal and minimizing ring flutter.
Double Pin Oilers: Double Pin Oilers deliver twice the amount of oil to the wrist pin as compared to the standard single pin oiler.
Pin Fitting: The pin bore is precision honed to attain an exact pin clearance. Clearances typically range from .0003 to .0010 between the wrist pin and pin bore.
Oil Squirt Notch: Notching can be done on pistons for motors with oil squirters, or to avoid contact between pistons and/or pistons and crankshaft.
Bottom Oilers: This process machines one or two holes into the bottom of the pin boss to assist in splash pin lubrication.
Tulip Valve Pockets: Most commonly used on Hemi and motorcycle engines, this process leaves a raised area on plunged valve pockets to achieve maximum compression.
What piston coatings are available from JE Pistons?
A. The thermal barrier crown coating is applied to the top of the piston and is designed to reflect heat into the combustion chamber, thereby increasing exhaust gas velocity and greatly improving scavenging potential. The .0015” thick coating can also assist in extending piston life by decreasing the rate of thermal transfer.
B. Skirt Coating. This is a “break-in” coating applied to the skirt of the piston only, designed to show wear. This coating is a .0003” to .0005” thick spray-on dry film that will help reduce friction and inhibit galling. No manufacturing allowance is required as this application is made to wear in to the cylinder wall.
C. Tuff Skirt is a JE Pistons’ trademark coating that is a lubricating, anti-friction / anti-wear coating applied to the piston skirt only. Unlike our standard Skirt Coating, Tuff Skirt will not wear and is designed to withstand many different types of endurance applications, similar to those commonly found in NASCAR. Buildup is .0005” per surface and finished diameter of skirt should include the coating buildup.
D. Top groove hard anodize, this coating has proven to increase power output by allowing for extremely tight ring clearances. Available exclusively to top-level racing teams until now, this top ring groove coating creates a hard mating surface which virtually eliminates microwelding while decreasing ring groove wear. Buildup is .00025” per surface and clearance must be added during manufacturing to accommodate the change.
E*. Anodize option B, also a ring groove coating, offers twice the buildup of the standard process (.0005” per surface). Through extensive R & D and field-testing, the Option B process has shown to be more durable in maximum effort, high endurance applications. Appropriate manufacturing allowances apply.
F*. Anodize Option C. This coating is the same material as the Anodize Option B except is applied to the wrist pin bore instead of the top ring groove. This coating provides increased lubricity, smoother oil transfer, and better wear in the pin bore. The wrist pin hole must be honed both before and after anodizing.
G. KoolKote is an aerospace quality hard anodize applied to all surfaces of the piston with a buildup of .001”. This coating is designed for use in nitro-methane engines such as Top Fuel Drag Racing to endure the corrosive effects of this fuel type. It will withstand greater temperatures and will not flake, chip or peel. This coating does alter the heat transfer and expansion characteristics of the piston. Consult the JE Pistons technical department for specific applications. Manufacturing allowances are required on all surfaces.
H. Oil Shed coating, this coating is applied to the underside of the piston. It is intended to reduce the reciprocating weight by repelling oil quicker than an untreated part. No additional manufacturing is required.
I. Armor Plate (not shown). This plating is applied to the piston domes, ring grooves, and wrist pin bores of pistons to provide an extremely low coefficient of friction, reduced piston ring blow-by, and detonation protection by reducing erosion caused by detonation. It also allows the domes to run 20 degrees C cooler and reflect heat back into the chamber for better combustion efficiency.
What is an FSR forging?
FSR (Forged Side Relief) forging designs feature a reduced skirt width and shorter wrist pin when compared to traditional “full round” style forgings. The narrow skirt helps minimize piston contact with the cylinder wall that can cause friction and power loss while the shortened wrist pins reduces the overall weight.
Some FSR forgings feature internal and external bracing to provide a more rigid construction while minimizing overall weight. With thousands of race miles logged in the most demanding applications, these pistons provide the ultimate combination of low-friction, lightweight design with increased stability and strength. (Tech note: In extreme horsepower applications the use of oil squirters may be required).
It is not always required to use an FSR forging to achieve significant weight reduction for a piston. 3D under-crown milling allows JE to precisely control the thickness of the piston crown, allowing for excess material to be removed out of the piston. In many cases, we've been able to make a full-found slipper skirt piston as light or lighter than an FSR, providing increased long term durability for a street engine.
What is the difference between the 2618 and 4032 forging alloy?
JE's 4032 forging alloy is created with a high-silicon content- 12 percent. Adding silicon reduces the expansion rate of the piston, allowing for tighter cold clearances. This reduces piston slap that can occur on a cold engine with a 2618 forging alloy, however there are drawbacks. A piston made from 4032 might have excellent wear rates, but the addition of silicon makes the piston less ductile and reduces fatigue resistance. A piston made out of 2618 alloy is stronger and can handle higher operating temperatures and stresses than a piston made out of 4032. Top ring groove hard anodize or JE's exclusive Armor Plate process when applied to a 2618 forged alloy piston provides superior long term durability, exceeding that of a 4032 piston. A 2618 forged alloy piston will expand 15% more than a 4032, requiring increased wall clearance than a 4032, but that's only half of the equation. Where a factory Mahle cylinder was cast out of an aluminum alloy with high silicon content and featured either cast or forged high-silicon content pistons to control expansion rates, LN Engineering's billet Nickies cylinders and sleeves are designed to work best with 2618 forged alloy pistons. If you are running cast iron cylinders or liners, we do offer custom 4032 alloy forged pistons, however you can still run a 2618 piston as long as proper clearances are observed.
SKU: LIB-0038Custom Piston Worksheet$0.00