Phenolic Thermal Spacer 8mm Impreza 99+, 2.5L N/A Legacy 00+




Collections: Intake System

Product type: Spacer

Vendor: GrimmSpeed

Tags: 00, 1999 forester, 1999 impreza, 2.5l, 2000 forester, 2000 impreza, 2000 legacy, 2001 forester, 2001 impreza, 2001 legacy, 2002 forester, 2002 impreza, 2002 legacy, 2003 forester, 2003 impreza, 2003 legacy, 2004 forester, 2004 impreza, 2004 legacy, 2005 forester, 2005 impreza, 2005 legacy, 2006 forester, 2006 impreza, 2006 legacy, 2007 forester, 2007 impreza, 2007 legacy, 2008 forester, 2008 impreza, 2008 legacy, 2009 legacy, 8mm, 99, a, impreza, legacy, n, phenolic, spacer, thermal



In response to the demand to extend our Phenolic Spacer lineup to include some of the older subaru models, we now have created intake manifold thermal spacers for Impreza/Legacy/Forester 99+ 2.5 N/A and 99+ 2.2 N/A 'Phase 2' engines.

Thermal spacers lift the intake manifold off the super heated engine to lessen the transfer of heat. Both the intake manifold and engine block are aluminum so the high heat transfers very quickly, these spacers stop that. The cooler the intake charge the more HP and TQ your engine will make.

In addition to cooling your intake charge, these will also give you larger intake volume similar to that of a throttle body spacer.

What it does:

  • Greatly reduces the transfer of heat from engine to intake manifold thus reducing heat soak.
  • One of a kind true Phenolic material, not cutting board material like others.
  • The cooler your intake temperature is, the denser the air is which leads to more power.
  • For every 5 degree reduction in temperature, increases power by 1%.
  • The cooler and denser the intake air that the engine sucks in, increases the amount of air that can be mixed with fuel thus increasing efficiency.
  • Direct bolt-on.
  • When running a gasket only, your intake manifold gets very hot to the touch, enough to burn your hand. When our gaskets are paired with our Phenolic Spacers, your hand can be placed on the intake manifold without any issues.
  • We do recommend using 2 sets of our gaskets, one on both sides of the spacers.

How it works:

  • The intake air in your engine travels through the airbox into the turbo, then into the aluminum intake manifold. The air exits the intake manifold and goes directly into the engine.
  • While the intake air is within the intake manifold it picks up a lot of heat from the aluminum intake manifold. This added heat reduces air density thus reducing engine power capabilities.
  • In stock form your engine has a steel gasket between the intake manifold and engine which allows the heat from the engine to quickly transfer into the intake manifold. By replacing this steel gasket with the GrimmSpeed Phenolic Spacers and gaskets you are greatly reducing the transfer of engine heat into the intake manifold.
  • Phenolic Spacers are able to withstand 500+ degrees F. Subaru engines run at the hotter end of operation around 200 degrees F, so the Phenolic Spacer is well within its max running temperature. GrimmSpeed has tested that it is also safe to run race fuel, E85 and methanol with the Phenolic Spacers.
  • The Phenolic Spacer will conduct 300-900 times less heat than the oem steel gasket.

Temperature Testing Data: Testing at 1/2 hour intervals. All testing was conducted fairly in Fahrenheit measurements on ONE day at a consistent outside temperature.

Test #1 - OEM measurement from IM without spacers, 152 degrees.

Test #2 - with 3mm phenolic spacers the temp dropped to 134 Degrees

Test #3 - With 8mm phenolic spacers the temp dropped to an outstanding 108 Degrees!!!

That is an OVER 44 Degree drop with the largest Phenolic Spacers!

Impreza, Forester 1999-2008 2.5L N/A
Impreza 1999+ 2.2 N/A
Legacy 2000-2009 N/A

Like our other thermal spacers we suggest putting GrimmSpeed gaskets on top and bottom of each spacer to allow for proper sealing.