Piston to cylinder wall clearance Please read the specification sheet provided with your pistons. Piston Diameter must be measured at the gauge point indicated in the diagram. Required clearance depends on diameter, alloy, type of forging (full, skirt or slipper), application, operating, conditions, etc. Recommended Ring Gap It is important to recognize that some end gaps for individual engines may vary from this standard because of engine manufacture’s requirements, type of application, fuels, etc. The top ring gap should be as small as possible to avoid blow-by. The table appearing below is for reference only. Top Ring Multiply the Bore diameter in inches by the following factor: Application
Factor
Street Performance
0.0045
Moderate Turbo / Nitrous
0.0050
Drag / Oval Track
0.0055
Turbo / Nitrous Race only
0.0065
Second Ring Multiply the First Ring Gap x 1.25
Oil Ring Gap Minimum Gap 0.015”
Oil Ring Installation Example: Subaru oil ring with rotational locking detent. The oil ring side rail’s are supplied with one or two tabs. One is installed with the tab facing the side of the groove designed to lock the rail using one of the grooves in the piston. The other tab (if applicable) is designed to lock the middle expander. Use at the top or the bottom is the same.
- Install the middle expander with end gap about 90 degrees from the wrist pin centerline. - Locate the upper notch in the oil ring groove. Install Lower Oil Ring Side Rail and rotate it until the tab falls in one of the oil grooves opposite to the upper notch. - Install the top oil Ring Side Rail and rotate it until the tab falls in the upper notch. TOP OIL RING RAIL GAP
UPPER NOTCH 2nd COMPRESSION RING GAP
OIL HOLES BOTTOM OIL RING RAIL GAP Wire Locks Installation Insert one end of the lock into the groove and continue spiral feeding until the lock is fully seated.
OIL RING EXPANDER & TOP COMPRESSION RING GAP
In addition to this form, please send a sample piston or pin, or supply a drawing / sketch of your piston requirements. Name:
Company:
Address: Telephone:
Fax:
`
E-mail:
Date: Engine Description: Naturally Aspired / turbo / supercharged: Boost pressure (if turbo or supercharged):
psi
Number of cylinders: Bore size: Stroke: Maximum power: Maximum torque: Maximum engine speed: Max. Water temperature (state if air cooled): C Compression ratio: Compression height: Deck clearance +/-: Head gasket thickness:
bhp Nm rpm
Rod Length: Rod small-end width: Thickness above pin: Piston type (circle one if known): Dome Pocket depth: Int: Exh: Pocket Angle: Int: Exh: Number of piston rings (2 or 3): Offset pin bore: Yes / No Piston designed for:
Flat Top
Camshaft Specs Gross valve lift: Int: Exh: Lobe separation (o): Duration @ .050: Int: Degreed in std. o: + o - o Valve lift @ TDC: Int: Exh:
Exh:
Dish