Forged Pistons for Subaru, EJ257 WRX STI (stroker), 100.5mm, 8.5:1 (CP Pistons SC7436)
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|
Make |
Subaru |
|
Model |
EJ257 WRX STI (stroker) |
|
Part Number |
SC7436 |
|
Cylinders |
4 |
|
Bore (in) |
3.957 |
|
Bore (mm) |
100.5 |
|
Size |
+1.0mm |
|
Stroke |
83 |
|
Conrod |
130.5 |
|
Comp Height (in) |
1.123 |
|
Comp Height (mm) |
28.5 |
|
Dom/Dish CC |
-23.7 |
|
Compression Ratio |
8.5 |
|
Weight (Grams) |
377 |
|
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 (stroker), 100.5mm, 8.5:1 (CP Pistons SC7436) |
|---|---|
| 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 SC7436 pistons?
For the SC7436 pistons, a typical bore clearance of 0.0010" to 0.0015" is recommended. This ensures proper thermal expansion and prevents piston scuffing. Always verify with your specific engine build requirements.
What compression ratio can I expect with the SC7436 pistons?
The SC7436 pistons have a compression ratio of 8.5:1 when used in an EJ257 WRX STI engine. This ratio is suitable for applications requiring a balance of power and reliability, particularly with forced induction setups.
Are the SC7436 pistons compatible with high lift camshafts?
Yes, the SC7436 pistons are designed with deep valve reliefs to accommodate high lift camshafts. This feature allows for increased airflow and performance without risking valve contact.
What is the weight of the SC7436 pistons, and how does it affect performance?
The SC7436 pistons weigh 377 grams each. Lighter pistons can improve engine responsiveness and reduce reciprocating mass, leading to better throttle response and higher RPM potential, provided the engine is properly balanced.
What type of wrist pins are included with the SC7436 pistons?
The SC7436 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 additional strength for high-performance applications.
