Pro Series High-Compression Piston Set

• 1985-1995 22R 2.4L Engines
• 1985-1995 22RE 2.4L Engines

CP Forged 94mm Piston Kit

When installing CPN or CPN2 piston rings, we recommend using a plateau hone with a cylinder bore cross-hatch angle of 35° to 40°.

Recommended Honing Process & Materials

To achieve the ideal surface roughness for gray cast iron engine blocks and Nikasil cylinders, manufacturers recommend a two-step honing process:

1. Initial Honing

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

2. Finish & Smoothing

After the initial hone, finish the surface to remove jagged peaks, torn material, or folded medal using one of the following methods:

• A fine-grit conventional abrasive (#400 - #600 grit).
• A flexible brush sweep of the bores.
• A nylon-bristle plateau honing tool.

Recommended Surface Roughness Specifications

Before honing, confirm with your equipment manufacturer that your chosen stone grit will achieve the following target roughness specifications.

• Rz (Average Peak-To-Valley Height): 59-138 microinches (1.5 to 3.5 micrometers)
• Ra (Roughness Average): 15 to 35 microinches (0.4 to 0.9 micrometers)

CP Piston Ring End Gap Guidelines

Critical Warning: Failure to properly check and set your piston ring end gap can result in catastrophic engine failure.

The recommendations provided below are general guidelines. The optimal ring gap varies based on your specific engine configuration and application. Increased clearance is typically required for extreme applications, including:

• Forced induction (Turbocharged / Supercharged)
• Nitrous Oxide (NOS) setups
• Filled engine blocks
• Endurance Racing

-Note: The final determination and execution of the proper end gap is the sole responsibility of the engine builder. For additional technical support, please contact CP directly at 949-567-9000.

Piston Ring Measurement & Installation Guidelines

The following steps are general guidelines for installing piston rings. Because certain high-performance setups require specific clearances, always consult the included charts and diagrams before final installation.

Step-by-Step Ring Gap Measurement

• Prepare the Block: If applicable to your engine, install a torque plate and torque it to factory specifications.
• Square the Ring: Position the piston ring into the cylinder bore, ensuring it sits flat, square, and completely below the deck of the surface.
• Measure the Clearance: Use a feeler gauge to accurately check the gap between the ring ends. 

-Important: If your measured ring gap is tighter than the recommended minimum for your bore size, you must carefully file-fit the rings to achieve the proper clearance. Failure to maintain a safe minimum gap can cause severe engine damage.

Ring Filing Process

• Use the right tool: Always check and adjust ring end gap using a dedicated ring gap filing tool.
• Filing Direction: File the ring ends in an inward direction (from the outside edge toward the center) to prevent chipping or damaging the outer face coating. Ensure the filed ends remain perfectly square to the sides of the ring.

-Technical Note on Bore Size: Ring sets are manufactured for precise cylinder bore dimensions. For every 0.001" the cylinder bore measures over its intended size, your ring end gap will increase by 0.00314".

Top Ring Orientation Guide:

Before installing the top piston ring, check its markings and profile to ensure correct orientation.

• Marked Rings: If the ring features a stamped dot or writing, always install it with the marked side facing up.
• Beveled Rings (Unmarked): If the ring is unmarked but features an inner bevel, install it with the bevel side facing up.
• Symmetrical Rings: If the ring has no dots, writing, or inner bevels, it can be installed either side up.

Second Ring Orientation Guide:

Before installing the second piston ring (scraper ring), carefully check its markings and groove profile to ensure proper orientation.

• Marked Rings: If the ring features a stamped dot or writing, always install it with the marked side facing up.
• Taper Hook Groove Style: If the ring features a taper hook groove, the groove must always be face down toward the bottom of the piston.
• Beveled Rings (Unmarked): If the ring if unmarked but features an inner bevel, install it with the bevel side facing down.
• Symmetrical Rings: If the ring has no dots, writing, or inner bevels, it can be installed either side up.

Oil Ring Orientation Guide:

• Three-Piece Assembly: Most CP oil rings consist of three separate components: two steel side rails and one center expander ring.
• Rail Clearance: The end gaps on the top and bottom rails must be at least 0.015". Ensure the rail ends do not overlap when installed.
• Do Not Modify: Never modify, file, or cut the center expander ring in any way.

Disclaimer & Warranty Policy

Due to the extreme demands of high-performance applications, all CP Pistons/Pankl products and services are sold strictly "as is" and "with all faults." 

• No Warranty: There no warranties, express or implied, including any warranty of merchantability or fitness for a particular purpose. Buyers are given full opportunity to inspect all parts and services prior to purchase.
• 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 tom damage to or loss of other property or equipment, loss of profits or revenue, costs of replacement goods, or any third-party claims resulting from the sale, installation, or use of these parts.