GrimmSpeed Phenolic Thermal Spacer 8mm 2002-2014 WRX / 2004-2021 STI / 2005-2012 Legacy GT / 2004-2013 Forester XT / 2005-2009 Outback XT

The GrimmSpeed Phenolic Thermal Spacer is the solution to the age-old problem of intake heat soak. By raising your intake manifold off the engine and replacing the stock steel gasket, you can dramatically reduce heat transfer from the engine to the intake.

Why Phenolic Spacers?

• Reduce Heat Soak: Phenolic material minimizes heat transfer from the engine to the intake manifold.
• True Phenolic Construction: Not cheap cutting-board material—engineered for high performance.
• Denser, Cooler Air: Every 5°F reduction in intake temperature can increase power by roughly 1%.
• Increased Efficiency: Cooler air allows more oxygen to mix with fuel for better combustion.
• Safe & Durable: Withstands 500+°F and is compatible with race fuel, E85, and methanol.

How It Works:
Air travels from the airbox into the turbo, then into the aluminum intake manifold, picking up heat along the way. The stock steel gasket transfers engine heat quickly to the manifold, reducing air density. GrimmSpeed’s Phenolic Spacers drastically reduce this heat transfer—conducting 300–900 times less heat than the OEM steel gasket. Pairing these spacers with our gaskets ensures a cooler manifold, even allowing you to touch it safely after driving.

Testing Results:

• OEM Steel Gasket: 152°F
• 3mm Phenolic Spacer: 134°F
• 8mm Phenolic Spacer: 108°F

That’s a 44°F+ reduction in intake manifold temperature with the largest spacer!

Features:

• Direct bolt-on installation
• Made in the USA
• Recommended: use two sets of gaskets—one on each side of the spacer