Forged Pistons for Subaru, EJ257 WRX STI (stroker), 100.5mm, 9:1 (CP Pistons SC7440)
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|
Make |
Subaru |
|
Model |
EJ257 WRX STI (stroker) |
|
Part Number |
SC7440 |
|
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 |
-18.2 |
|
Compression Ratio |
9 |
|
Weight (Grams) |
394 |
|
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, 9:1 (CP Pistons SC7440) |
|---|---|
| Brands | CP Carrillo |
| Engine | EJ257 WRX STI |
| Make | Subaru |
Delivery & Freight
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If you are unsure, get in touch by emailing [email protected], messaging us on Facebook, or phoning us at +61 7 5645 1333 (8am to 2pm AET).
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 SC7440 pistons?
For the SC7440 pistons, a typical bore clearance of 0.0015" to 0.0025" is recommended. However, this can vary based on the specific application and operating conditions, so always consult with your engine builder for the best fit.
What compression ratio do the SC7440 pistons provide?
The SC7440 pistons are designed to achieve a compression ratio of 9:1 when used in the EJ257 WRX STI engine. This ratio is suitable for a balance of performance and reliability, particularly with moderate boost levels.
Are the SC7440 pistons compatible with aftermarket camshafts?
Yes, the SC7440 pistons feature deep valve reliefs that accommodate high lift camshafts and oversized valves, making them suitable for use with various aftermarket performance camshafts.
What is the weight of the SC7440 pistons, and how does it affect performance?
The SC7440 pistons weigh 394 grams each. This weight is beneficial for performance applications as it helps reduce reciprocating mass, allowing for quicker engine response and higher RPM capabilities.
What type of wrist pins are included with the SC7440 pistons?
The SC7440 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 seeking additional strength for high power applications.
