GrimmSpeed Phenolic Thermal Manifold Spacer WRX/STI/FXT/LGT - 3mm

( 4 Reviews )
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GrimmSpeed 3mm Subaru WRX STI Phenolic Thermal Spacer
Do you know what your intake manifold sits on?...a superheated boxer engine. If you don't know already, the cooler your intake air is the more HP your car will achieve. We present you the answer to this age old problem, raising the intake manifold off the engine with GrimmSpeed's Phenolic Intake Manifold/TGV to Engine Thermal Spacer

Phenolic spacers have been used for years by many other specialized automotive companies, but this is new technology to the Subaru world.

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 air temperature, increases power by 1%.
  • Cooler and denser intake air, increases the amount of air that can be mixed with fuel thus increasing efficiency.
    GrimmSpeed 3mm Subaru WRX STI Phenolic Thermal Spacer
  • 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.
    GrimmSpeed 3mm Subaru WRX STI Phenolic Thermal Spacer
  • 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 Spacer 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!

WRX '02-'14
STI '02-'21
Legacy GT 04-'09
Forester XT '04-'13

4 Reviews

Andrew Kapczynski 15th Nov 2013

spacers are amazing and really do work

These spacers are amazing and really do work. Before I installed mine, I could barely touch my intake it was so hot just from warming up and idling. Now that I have them I can do a 10 minute heat and my intake never gets hot. In-fact my intake didn't get much above ambient temp. I wish I had a checked the temp with a laser before so I could give an accurate number of how much cooler my intake is now. I am a true believer in this product. I have made my own before and they are very difficult to make, which is why I understand how much they cost to purchase. Phenolic is a very abrasive material which makes it very difficult to cut. They cannot be cut out with lasers or milling machines. The only way to get a clean cut without destroying every bit or blade within 100 miles is to use a waterjet. Believe me I tried bandsaws, cnc, and laser cutting. Not to mention the toxic dust and smoke that is created. You will be amazed at what these do for your intake temps, I was!

Ryan Schram 15th Nov 2013

Works as advertised

"I picked these up since I was doing TGV deletes anyway. Works as advertised, and your car and tuner will appreciate them too! I replaced the steel gaskets with these (no more steel ones). no leaks so far as I can tell."

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