Forged Pistons for Subaru, EJ257 WRX STI (stroker), 99.5mm, 9:1 (CP Pistons SC7437)
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|
Make |
Subaru |
|
Model |
EJ257 WRX STI (stroker) |
|
Part Number |
SC7437 |
|
Cylinders |
4 |
|
Bore (in) |
3.9175 |
|
Bore (mm) |
99.5 |
|
Size |
STD |
|
Stroke |
83 |
|
Conrod |
130.5 |
|
Comp Height (in) |
1.123 |
|
Comp Height (mm) |
28.5 |
|
Dom/Dish CC |
-16.7 |
|
Compression Ratio |
9 |
|
Weight (Grams) |
391 |
|
Pin (mm) |
23 |
|
Rings |
RS1658-3917-0 |
|
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), 99.5mm, 9:1 (CP Pistons SC7437) |
|---|---|
| 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 SC7437 pistons?
The recommended bore clearance for the SC7437 pistons in the EJ257 engine typically ranges from 0.0025" to 0.0035". However, it's crucial to measure the specific bore and piston dimensions to ensure proper fitment, as clearances can vary based on the engine builder's preferences and the intended use of the engine.
What compression ratio do the SC7437 pistons provide?
The SC7437 pistons have a compression ratio of 9:1. This ratio is suitable for a balance of performance and reliability, but keep in mind that actual compression may vary based on head gasket thickness and combustion chamber volume, so it's essential to verify these factors during assembly.
Are the SC7437 pistons compatible with high lift camshafts?
Yes, the SC7437 pistons feature deep valve reliefs designed to accommodate high lift camshafts and oversized valves. This makes them a good choice for performance builds aiming for increased airflow and power output.
What type of wrist pins are included with the SC7437 pistons?
The SC7437 pistons come with standard wrist pins (part number 905-2500-18CP1S) included at no additional cost. Upgraded and ultra-duty wrist pins are also available for those looking to enhance durability in high-performance applications.
What machining processes should be considered when using SC7437 pistons?
When using SC7437 pistons, it's important to ensure the cylinder bores are honed to the correct specifications for proper clearance. Additionally, the pistons should be balanced with the full rotating assembly to avoid vibrations and ensure optimal performance. Always consult with your engine builder for specific machining requirements.
