Improved Racing designed this billet aluminum rear passage plug (commonly known as the "barbell") to improve oil flow and completely eliminate dirty engine oil from bypassing the filter.

• Improved Racing's barbell features a second O-ring that completely seals off the dirty oil from the clean oil, forcing 100% of oil flow through the filter.
• Sharp corners were avoided and machined as smooth fillets to improve oil flow, while the bullnose tip helps smooth oil flow to the oil filter.
• The shaft diameter is smaller than the OEM plastic barbell to minimize flow restriction. A threaded hole was added to the end of the plug so that it can be easily removed with any M4x0.7 screw.
• Because it's machined from aluminum, the plug will never degrade. Simply replace the two O-rings with any rebuild.

Why Replace the Factory Oil Passage Plug?

• The factory oil passage plug (shown on the left) is made from plastic, which degrades over time, compromising the seal. Simply replacing the O-ring is not enough. It is therefore recommended that the entire plug be replaced with every engine build.
• The factory plug does not seal the passage perfectly due to manufacturing tolerances and cost. It's simply not possible to make a plug that will fit perfectly in every engine bore, and still allow for removal, because the bore itself has a manufacturing tolerance (+/- 0.005", for example).
• The ridges on the front of the OEM plastic unit are an attempt to make the plastic more malleable so it deforms into the hole, creating a better seal. In practice, it doesn't seal very well, and the plastic degrades over time, allowing oil to flow around it.
• Adding an O-ring to the end of the plug creates a positive seal that can account for tolerances and completely prevent any oil from bypassing the filter.
• Improved Racing's passage plug is reusable, lifetime part. It can be reused over and over with every engine build by simply replacing the O-rings.

Specifications