Pro Piston Set | 22R/22RE

• 1981-1984 22R 2.4L Engines
• 1983-1984 22RE 2.4L Engines

CP Forged Piston Set

When installing these 94mm CP Pistons with CPN or CPN2 piston rings, achieving the correct cylinder wall finish is critical for proper ring seating and optimal engine performance.

• Honing Specifications: Plateau honing
• Cross Hatch Angle: 35-40°

Honing Recommendations & Surface Finishing

To achieve the proper surface roughness for gray cast iron engine blocks and Nikasil cylinders, top honing machine manufacturers recommend a two-step process to ensure optimal ring seating and longevity.

Step 1: Initial Honing Roughness

Begin the honing process using one of the following grit specifications based in your stone material:

• Conventional Stones: #220-#280 grit
• Diamond Stones: #325-#550 grit

Step 2: Final Plateau Finishing

After the initial hone, finish the cylinder bores to eliminate jagged peaks, folded metal, ir torn material. Use one of the following methods to create a smooth, durable plateau finish:

• Fine Abrasive: A fine-grit conventional stone (#400-#600 grit)
• Brushing: Sweeping the bores with a flexible brush or a nylon-bristle plateau honing tool

Surface Roughness Specifications

• Note: Always verify with your honing equipment manufacturer that the selected stone grits will achieve the precise Rz and Ra roughness specifications listed below.

1. Rz Roughness: 59 - 138 μin (1.5 - 3.5 μm)
2. Ra Roughness: 15 - 35 μin (0.4 - 0.9 μm)
   
   

CP Piston Ring End Gap Guide

Critical Warning: Failure to properly check and set the ring gap can result in severe, catastrophic engine failure. The final end gap setup is the sole responsibility of the engine builder.

The recommendations provided below are general guidelines. Optimal ring gaps vary based on your specific engine build and application. Increased clearance is required for high-stress applications, including:

• Forced induction (Turbocharged/Supercharged)
• Nitrous oxide systems
• Filled engine blocks
• Endurance racing and other extreme operating conditions

If you have technical questions or need specific clearance advice, please contact technical support at 949-567-9000.

How to Calculate Ring End Gap

To determine your required ring end gap, locate your specific application in the reference table below. 

• Note: All cylinder bore measurements must be converted to inches before calculating. 

1. Bore in Millimeters divided by 25.4 = Bore in Inches
2. Bore in Inches x Application Factor = Required Ring End Gap

Calculation Example (Street Application)

If your cylinder bore size is 81mm:

1. Convert to inches:

81 mm divided by 25.4 = 3.189 in

2. Calculate top ring gap:

3.189 in x 0.005 = 0.016" end gap

Piston Ring Installation & Measuring Procedures

Important: The instructions below are general guidelines. Certain high-performance or heavy-duty applications may require alternative clearances. Always consult the specific charts and diagrams included with your kit before final installation.

Step-by-Step Ring Gap Measurement

1. Torque Plate Installation: Install a torque plate onto the engine block (if applicable to your build) and torque it completely to factory specifications to simulate true cylinder distortion.
2. Squaring the Ring: Position the piston ring into the cylinder bore. Ensure it sits perfectly square and level below the deck surface.
3. Measuring the Gap: Use a precise feeler gauge or dedicated ring gap measuring tool to check the clearance between the ring ends.

• Technical Note: If the measured ring gap is tighter than the minimum clearance specified for your exact bore size, you must file-fit the rings to achieve the proper end gap. Running an insufficient gap will cause the ring ends to butt together under thermal expansion, leading to severe engine damage.

Piston Ring Filing Procedures

When adjusting ring clearance, proper filing technique and correct orientation are critical to ensure a proper seal and prevent engine damage.

• Filing Method: Always use a dedicated manual or electric piston ring squaring/filing tool.
• Filing Direction: File the ring end in an inward direction (from the outside face toward the inside face) to prevent chipping or peeling the specialized outer face coatings. Keep the ring square to the grinding wheel.

Ring Orientation & Facing

Before final installation onto the piston, carefully verify the orientation of each ring

1. Top-Facing Markers: If the piston ring features an etched dot, laser-marked letters, or writing (e.g., a brand mark or size code), it must be installed with that marked side facing up toward the cylinder head.
2. Taper Hook Groove Style: If the ring uses a taper hook groove design (scraper ring), ensure the groove is oriented correctly according to the enclosed instruction sheet, keeping the face completely square to the cylinder wall.

• Technical Note: CP Piston ring sets are precision-manufactured to fit specific, standard bore sizes. For every 0.001" the actual cylinder bore measures over the ring set's intended nominal bore size, your ring end gap will automatically increase by approximately 0.00314"

Second Ring Installation & Orientation

Before installing the second (scraper) compression ring, inspect it carefully to identify its design and markings. Incorrect orientation will cause high oil consumption and poor cylinder pressure retention.

• Marked Rings: If the ring features an etched dot, laser-marked letters, or writing, install it with the marked side facing up toward the cylinder head.
• Taper Hook Groove Style: If the ring has a taper hook groove profile, the groove must always face down toward the oil control ring pack.
• Inner Bevel Style (Unmarked): If the ring is completely unmarked but features a distinct inner step or bevel, install it with the bevel facing down toward the bottom of the piston.
• Standard/Symmetric Rings: If the ring is completely unmarked has no inner bevel or groove, it can be installed with either side up.

Oil Ring Pack Installation & Clearance

Most CP Piston high-performance oil rings utilize a three-piece design consisting of two steel rails and a central expander. Proper installation ensures correct oil control and prevents premature cylinder wall wear.

• Oil Rail Clearance: Check the end gaps on both the top and bottom oil rails before final assembly. The end gap must not be less than 0.015".
• Rail Alignment: When checking clearance and positioning the rails in the cylinder, ensure the ring ends do not overlap.
• Expander Care: Do not cut, file, bend, or modify the central expander assembly in any way. Modifying the expander will alter the precise radial tension of the oil ring pack, leading to oil bypass or ring binding.

Disclaimer & Warranty Policy

Due tp the severe stress and unpredictable nature of high-performance racing and automotive applications, all CP Pistons/Pankl products and services are sold strictly on an "As Is" and "With All Faults" basis.

No Warranty Expressed or Implied

There are no warranties, either express or implied, including any implied warranty of merchantability or fitness for a particular purpose. It is expressly understood and agreed between CP Pistons/Pankl and the purchaser that the entire risk as to the quality and performance of these parts is with the buyer. The purchaser is provided a full and complete opportunity to examine all parts, inventory, and services prior to installation or use.

Limitation of Liability

• CP Pistons/Pankl shall not, under any circumstances, be held liable for any special, incidental, or consequential damages. This includes, but is not limited to:
• Damage or loss of other property or equipment
• Loss of profits, revenue, or business options
• Cost of purchased or replacement goods
• Any-third party claims from customers of the purchaser arising from the sale, installation, or use of these components.