Phenolic Thermal Spacer 8mm Impreza 98, 2.5 N/A Legacy 96-99




Collections: Intake System

Product type: Spacer

Vendor: GrimmSpeed

Tags: 1996 legacy, 1997 legacy, 1998 impreza, 1998 legacy, 1999 legacy, 2.5, 8mm, 96, 98, 99, a, impreza, legacy, n, phenolic, spacer, thermal



NOTE: When installing spacer on at Impreza Phase 1 Engine you will have to cut your EGR tube in half and insert a heater hose between the the halves of the EGR tube to extend it.

GrimmSpeed™  Subaru Phenolic Spacer
GrimmSpeed™  Subaru Phenolic Spacer

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 '98 and Legacy '96-'99 2.5L N/A 'Phase 1 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.
      • USA MADE.

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 '98 2.5L N/A Phase 1 engines
Legacy '96-'99 2.5L N/A Phase 1 engines

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