What is the part number of the radiator cap on a Subaru STI?

Part Number of the Radiator Cap for Subaru STI
The part number of the radiator cap for a Subaru STI is ST4511355010. This high-pressure radiator cap increases the pressure rating of the cooling system from.9 bar (13.0 lbs.) to 1.3 bar (18.9 lbs), allowing for more efficient cooling under demanding conditions.
The STI radiator cap has a pressure rating of 1.3bar and is a direct replacement for the radiator cap(s) on turbo Subaru vehicles, including the WRX (2002-2015), WRX STI (2004-2015), and 2.5i (2006-2007), as well as the Forester XT, XT Premium, XT Ltd., & Sports (2004-2008).
This part is also referred to as the Subaru STI 1.3 BAR Radiator Cap and is designed to fit a wide variety of Subaru vehicles, including the WRX (2002-2015), WRX STI (2004-2015), 2.5i (2006-2007), and Forester XT, XT Premium, XT Ltd., & Sports (2004-2008).
It’s important to note that the STI radiator cap is a high-pressure cap designed to improve the cooling efficiency of the vehicle.
If you have any further questions or need assistance with anything else, feel free to ask!

What are the numbers on the top of the radiator cap?

The cap’s pressure rating has nothing to do with regulating your engine’s coolant temperature, nor will it make your engine run cooler. Depending upon the original application you will see original radiator caps rated for anywhere from 13 psi up to 18 psi.

What is the pressure at 1.1 radiator cap?

All modern automotive cooling systems are under pressure, completely regulated by the radiator cap. 1.1 bar is roughly 15psi, and 1.3 bar is around 18psi.

What is a 1.8 radiator cap?

The 1.8 Radiator Cap greatly reduces fluid being blown out when temperatures increase. This radiator cap is used on every one of our in-house race team bikes. Help keep your coolant in the radiator where it belongs.

What is the difference between 1.1 and 1.8 radiator cap?

A 1.1 kg/mm2 cap can handle 14.22 psi before the coolant pushes the valve open and steam comes out the overflow. By increasing the radiator cap to 1.8 kg/mm2, the radiator can handle 25.6 psi, while a 2.0 kg/mm2 cap ups the ante to 28.45 pounds.

What is the difference between 1.1 and 1.3 radiator cap?

Raising the pressure capability of the cooling system won’t strain anything unless and until the cooling system actually reaches that pressure. Adding a 1.3 Bar radiator cap will not change the actual pressure of the coolant until it gets hotter than the designed for temperature it reaches at 1.1 Bar.

What does number on radiator cap mean?

A radiator cap will have two pressure measurements on it, psi and kPa. Psi measures pound per square inch and kPa stands for kiloPascals. They are both used to calculate pressure and depend on whether the system uses imperial or metric units of measurement.

Will a lower pressure radiator cap cause overheating?

A faulty radiator cap can result in engine overheating, loss of coolant or major engine damage. So, Pressurized cooling systems help prevent overheating and coolant loss. Also, It raises the coolant boiling point about 3-degrees F for each additional psi above atmospheric pressure.

How do I know what radiator cap to buy?

Based On Pressure Rating
It is very important to learn about the appropriate pressure rating for your vehicle’s radiator cap. Depending on the model of your car, each cap is unique. The correct pressure rating for your car is usually specified in the manual.

What is the radiator cap pressure for a Subaru STI?

1.3bar
Made by Subaru, the STI radiator cap has a pressure rating of 1.3bar and features the STI logo over a ‘cherry blossom’ pink signature background.

Is higher psi radiator cap better?

A high-pressure radiator cap is used to raise the boiling point. This protects the system from boiling over at the top of the operating temperature range. High-performance engines also create more heat. Higher pressure caps can boost the boiling point even more.