GrimmSpeed 1.3 Bar Radiator Cap – Subaru Universal

The Correct Pressure Cap for a Modified Subaru Cooling System

The GrimmSpeed 1.3 Bar Radiator Cap for Subaru universal fitment is a higher-pressure replacement for the factory radiator cap that raises the system pressure ceiling to 1.3 bar (approximately 18.9 psi). Higher system pressure raises the boiling point of coolant, providing more headroom before coolant vaporizes under sustained hard driving or track use. The billet aluminum construction and GrimmSpeed logo make it a visual upgrade over the factory plastic cap as well.

Why 1.3 Bar vs Factory Pressure

The factory Subaru radiator cap operates at a lower system pressure designed for a stock cooling system. A higher pressure cap raises the boiling point of the coolant — water boils at a higher temperature under higher pressure, so the same coolant mixture stays liquid at temperatures that would cause vaporization and localized hot spots at stock pressure. On a modified Subaru that produces more heat than stock, the 1.3 bar cap provides meaningful additional headroom.

Universal Subaru Fitment — Direct Replacement

The GrimmSpeed 1.3 bar cap threads directly onto the factory radiator cap location on Subaru EJ and FA-series cooling systems. No modification required. The billet aluminum body maintains its appearance over time unlike factory plastic caps that yellow and crack in the engine bay environment.

Key Features

• Universal Subaru EJ and FA-series fitment
• 1.3 bar (18.9 psi) operating pressure — higher than factory cap
• Raises coolant boiling point under pressure
• Billet aluminum construction — machined GrimmSpeed logo
• Direct replacement for factory radiator cap

Fitment Notes

• Universal Subaru fitment — EJ and FA-series cooling systems
• Direct replacement at factory radiator cap location
• 1.3 bar pressure — verify compatibility with cooling system components before use

Straight From Subispeed

The GrimmSpeed 1.3 bar radiator cap is a small purchase with a real function — it raises the coolant system’s boiling threshold, which matters on any Subaru that’s been modified to produce more heat than stock. Combined with a quality coolant and a proper flush, it’s the correct cap for a built engine bay. The billet aluminum look is a bonus.

What’s Included

• GrimmSpeed 1.3 Bar Radiator Cap — Black

About GrimmSpeed

GrimmSpeed is a Pacific Northwest-based performance parts manufacturer that has been building Subaru-specific hardware since 2003. Founded by engineers who were actively building and racing Subarus themselves, GrimmSpeed’s catalog reflects the priorities of people who use the products they make — turbo inlets, downpipes, uppipes, boost controllers, intercoolers, and engine bay accessories designed specifically for the EJ and FA-series Subaru platforms. Every GrimmSpeed product is engineered, tested, and refined in-house, and their focus on Subaru means the fitment and function reflect a deep understanding of the specific platforms they cover. Subispeed carries the full GrimmSpeed catalog because their approach to product development consistently produces parts that perform as advertised and fit correctly out of the box.

Year	Make	Model	Notes
Universal	Subaru	EJ/FA-series	All models — verify cooling system cap fitment