Forged Pistons for Subaru, EJ255 WRX, 100mm, 8.4:1 (CP Pistons SC7431)
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|
Make |
Subaru |
|
Model |
EJ255 WRX |
|
Part Number |
SC7431 |
|
Cylinders |
4 |
|
Bore (in) |
3.937 |
|
Bore (mm) |
100 |
|
Size |
+0.5mm |
|
Stroke |
79 |
|
Conrod |
130.5 |
|
Comp Height (in) |
1.208 |
|
Comp Height (mm) |
30.7 |
|
Dom/Dish CC |
-24.3 |
|
Compression Ratio |
8.4 |
|
Weight (Grams) |
396 |
|
Pin (mm) |
23 |
|
Rings |
RS1658-3937-0 |
|
Ring Thickness |
1.2 x 1.2 x 2.0mm |
|
Pin included (Standard) |
905-2500-18CP1S |
|
Upgraded Pin |
905-2500-20CP3S |
|
Ultra Duty Pin |
905-2500-26CP3S |
|
Locks |
905x055 SUB |
CP pistons are compatible with oversized valves and high lift camshafts. CP Pistons represent the highest quality and is engineered for maximum power. Standard features include: Deep valve reliefs accommodate high lift camshafts; Larger valve reliefs for +1mm valve sizes; Custom skirt cam and barrel design; Accumulator grooves; High strength aluminum forgings; High performance rings; Fully CNC machined and balanced to +/- 1 gram; Wrist pins included at no additional cost; Double pin oilers force fed from oil ring groove; Pin lock grooves for easy lock removal; Pin fitting included.
| Product Name | Forged Pistons for Subaru, EJ255 WRX, 100mm, 8.4:1 (CP Pistons SC7431) |
|---|---|
| Brands | CP Carrillo |
| Engine | EJ20 / EJ25 / EJ255 / EJ257 |
| Make | Subaru |
Delivery & Freight
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What information do I need to match these pistons to my engine?
You need the engine code, bore size, stroke, rod length, pin diameter and target compression ratio. These determine the correct piston compression height and crown design.
How should ring gaps be set for these pistons?
Ring gaps must be set by your engine builder based on fuel type, boost level and the intended rpm range. Forced-induction engines usually require larger gaps.
Are forged pistons suitable for street engines?
Yes. Forged pistons handle detonation and high cylinder pressure better than cast units. Your builder should set the piston-to-bore clearance to suit your application.
What is the recommended bore clearance for the SC7431 pistons?
For the SC7431 pistons, a typical bore clearance of 0.0015" to 0.0020" is recommended. However, this can vary based on the specific engine build and operating conditions, so always consult with your engine builder for precise measurements.
What compression ratio can I expect with the SC7431 pistons in my EJ255?
The SC7431 pistons provide a compression ratio of 8.4:1 when used with the standard EJ255 configuration. Keep in mind that actual compression may vary based on head gasket thickness and any modifications to the cylinder head.
Can I use the SC7431 pistons with upgraded valve sizes?
Yes, the SC7431 pistons are designed with deep valve reliefs, making them compatible with oversized valves and high lift camshafts. Ensure that your cylinder head modifications are compatible with the piston design for optimal performance.
What type of wrist pin is included with the SC7431 pistons?
The SC7431 pistons come with standard wrist pins (part number 905-2500-18CP1S) included at no additional cost. If you require upgraded or ultra-duty pins, options are available for purchase separately.
How are the SC7431 pistons balanced?
The SC7431 pistons are fully CNC machined and balanced to within +/- 1 gram. This precision ensures that they perform reliably at high RPMs, which is crucial for performance applications.
