Forged Pistons for Subaru, EJ257 WRX STI, 100.5mm, 8.2:1 (CP Pistons SC7423)
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|
Make |
Subaru |
|
Model |
EJ257 WRX STI |
|
Part Number |
SC7423 |
|
Cylinders |
4 |
|
Bore (in) |
3.957 |
|
Bore (mm) |
100.5 |
|
Size |
+1.0mm |
|
Stroke |
79 |
|
Conrod |
130.5 |
|
Comp Height (in) |
1.208 |
|
Comp Height (mm) |
30.7 |
|
Dom/Dish CC |
-21 |
|
Compression Ratio |
8.2 |
|
Weight (Grams) |
384 |
|
Pin (mm) |
23 |
|
Rings |
RS1658-3957-0 |
|
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, EJ257 WRX STI, 100.5mm, 8.2:1 (CP Pistons SC7423) |
|---|---|
| Brands | CP Carrillo |
| Engine | EJ257 WRX STI |
| 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 SC7423 pistons?
For the SC7423 pistons, a typical bore clearance of 0.0015" to 0.0025" is recommended. However, this can vary based on the specific application and the engine builder's preferences. Always consult with your engine builder for the best fitment.
What compression ratio can I expect with the SC7423 pistons in an EJ257 engine?
The SC7423 pistons provide a compression ratio of 8.2:1 when used in an EJ257 engine. This ratio is suitable for applications requiring lower compression, such as those running higher boost levels.
What type of wrist pins are included with the SC7423 pistons?
The SC7423 pistons come with standard wrist pins (part number 905-2500-18CP1S) included at no additional cost. Upgraded and ultra-duty pins are also available for those seeking enhanced performance.
Are the SC7423 pistons compatible with high lift camshafts?
Yes, the SC7423 pistons feature deep valve reliefs designed to accommodate high lift camshafts, making them suitable for performance builds that require such modifications.
What is the weight of the SC7423 pistons, and how does it affect performance?
The SC7423 pistons weigh 384 grams each. This weight is optimal for performance applications, as it helps reduce reciprocating mass, allowing for quicker engine response and higher RPM potential.
