What size is the intake manifold on a Subaru?
There isn’t a single Subaru intake-manifold size—the correct size varies by engine family and model year.
Subaru uses multiple engine designs across its lineup, including older EJ-series motors, newer FA/FB-series engines, and other variants like EZ. Each engine family can have different plenum volumes, runner geometries, and throttle-body interfaces, which means the intake manifold size is not universal. To determine your exact size, you must identify the engine code and year and then refer to the official specifications or parts catalogs. The sections below outline how to approach this question and what to check for your specific vehicle.
Engine families and how they influence manifold size
Below is a concise look at how the main Subaru engine families influence intake-manifold design. The exact dimensions still depend on model year and market, but understanding the family helps orient your search.
- EJ family (older, widely used from the 1990s through the early 2010s): manifold designs vary by displacement and configuration; both naturally aspirated and turbo variants have different runner sizes and plenum geometries.
- FA/FB family (modern four-cylinder engines introduced in the mid-2010s): redesigned manifolds with updated runner geometry; turbo versions (such as in WRX/STI) use distinct plenums and throttle-body interfaces compared to naturally aspirated versions.
- EZ family (later, including larger-displacement applications): intake manifolds optimized for higher flow and torque, with varying runner geometries and throttle-body interfaces across models.
In practice, the exact intake-manifold size you’ll encounter is tied to your engine code and model year. The general takeaway is that there is no universal spec that covers all Subarus.
How to determine the exact intake-manifold size for your Subaru
Following these steps will help you identify the precise size and ensure compatibility for replacements or upgrades.
- Identify your engine code and model year. Look at the vehicle’s VIN or the engine tag on the engine itself to find codes such as EJ25, FA20D, EZ36, etc.
- Consult the official Subaru parts catalog or service manual for that engine code and year to locate the intake manifold part number and the corresponding port/runner dimensions.
- If you’re replacing the manifold, measure the throttle-body bore and compare it to the manifold inlet to verify compatibility with the existing throttle body.
- When removing or inspecting the manifold, measure the intake-port diameters for each cylinder to confirm port size and ensure an exact match for replacement or tuning parts.
- When in doubt, contact a Subaru dealer or a qualified mechanic with your engine code and VIN to confirm the exact size and compatible parts.
By following these steps, you’ll confirm the precise intake-manifold size for your specific Subaru powertrain, avoiding mismatches that could affect fitment or performance.
Summary
For Subaru vehicles, there is no universal intake-manifold size. The correct size hinges on the engine family, whether the engine is naturally aspirated or turbocharged, and the model year. Identifying the exact engine code and consulting official Subaru documentation or a qualified technician is the best path to determine the precise manifold size and ensure proper fitment for replacements or upgrades.
