Forged Pistons for Subaru, EJ257 WRX STI, 100.5mm, 9:1 (CP Pistons SC7428)
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|
Make |
Subaru |
|
Model |
EJ257 WRX STI |
|
Part Number |
SC7428 |
|
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 |
-15.6 |
|
Compression Ratio |
9 |
|
Weight (Grams) |
393 |
|
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, 9:1 (CP Pistons SC7428) |
|---|---|
| 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 SC7428 pistons?
For the SC7428 pistons, a typical bore clearance of 0.0015" to 0.0025" is recommended. However, final clearance should be determined based on the specific application and the builder's experience.
What compression ratio can I expect with the SC7428 pistons in an EJ257 engine?
The SC7428 pistons provide a compression ratio of 9:1 when used in the EJ257 engine. This ratio is suitable for a balance of performance and reliability, particularly when tuning for boost.
Are the SC7428 pistons compatible with upgraded wrist pins?
Yes, the SC7428 pistons come with standard wrist pins included, but they are also compatible with upgraded options such as the 905-2500-20CP3S or the ultra-duty 905-2500-26CP3S for enhanced strength in high-performance applications.
What type of rings are included with the SC7428 pistons?
The SC7428 pistons include high-performance rings specified as RS1658-3957-0, featuring a thickness of 1.2 x 1.2 x 2.0mm. These rings are designed to provide optimal sealing and performance under high-stress conditions.
Do I need to modify my engine for the SC7428 pistons?
While the SC7428 pistons are designed with deep valve reliefs to accommodate high lift camshafts and oversized valves, it's essential to ensure that your engine's cylinder head and camshaft setup are compatible. Always verify clearances during assembly.
