Sport Compact Pistons for Subaru EJ257 WRX STI


CP Pistons

CPP SC7422

In stock - Ships Today if ordered in the next:

This piston is designed to be used with a standard-stroke Crank in an EJ257 block with a standard-length connecting rod. This combination works out to a 2.5L depending on bore size.

Bore Diameter: 99.75mm
Pin Size: -0.905in / 23mm
Stroke: 79mm
Rod Length: 5.137in / 130.5mm

Compression Ratio: 8.2:1
This piston maintains the standard compression ratio.

Bore Size:
The bore size of this piston is larger than stock. That means the cylinder will need to be bored to match these pistons. We recommend not having the block bored till the machine shop has the pistons in-hand. The block should be bored to YOUR pistons.

File to Fit Rings:
These pistons come with file-to-fit rings. This means the rings come slightly-long, and MUST be filed to the desired ring-gap for your application. This ring gap can vary depending on what your engine will be used for. For example, a 1000hp drag-only application will have a much different ring gap than a 300hp daily driven engine. Consult with your engine builder before filing your rings, and do not install the rings without filing them.

These pistons, like many aftermarket pistons, are made of 2618 alloy. 2618 is a strong, durable, forged aluminum alloy that can withstand a large amount of abuse in race applications.

If you are installing these pistons yourself, there are some tools you will need to install them in your engine correctly. We can help supply you with these tools if you don't already have them. At the very minimum you will need a quality torque wrench and a ring compressor. You should also get a quality bolt-stretch gauge to properly torque your rod bolts.

Returns Policy

You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the 'Complete Orders' link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.


We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

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