How do I know my throttle body size?
To know your throttle body size, identify the bore diameter in millimeters or locate the exact part number on the throttle body and cross-check with your vehicle’s specifications. In most cases, the bore is the key dimension that determines compatibility and airflow.
Throttle bodies come in different shapes and sizes, especially with drive-by-wire systems or multi-throttle configurations. The size matters for replacement parts, performance upgrades, and tuning. Here’s how to reliably determine the correct size for your engine and vehicle.
Ways to Determine Throttle Body Size
There are several reliable ways to identify the correct size without guessing. Use one or combine several methods for verification.
- Check for a stamped part number on the throttle body. Use the digits to look up the exact model and bore size in the original equipment manufacturer (OEM) parts catalog or the dealer's database.
- Measure the bore diameter with a caliper. Use a digital or dial caliper to measure the internal circle at the widest point; report the measurement in millimeters. This is the most direct way to know the size if the part number is unclear or missing.
- Consult the vehicle’s service manual or manufacturer official specs. The manual or the manufacturer's website typically lists throttle body size for each engine code or VIN-based configuration.
- Use the VIN and engine code to fetch OEM parts data online. Many manufacturers and parts distributors let you enter the VIN to retrieve the exact throttle body part and its bore size.
- Cross-reference replacement part numbers when upgrading. If you’re upgrading to a larger or smaller TB, verify that the replacement’s bore diameter matches your engine’s intake manifold and required airflow characteristics.
- If in doubt, contact a dealer or certified mechanic. Provide your VIN and engine code to confirm the correct throttle body size and compatibility.
Accurate size identification helps prevent idle issues, misfires, and intake leaks, and it ensures your replacement TB mates correctly with the intake manifold and sensors.
How to Measure the Bore: Step-by-Step
When you don’t have a parts catalog handy, a careful measurement of the bore is a reliable next step. Follow these steps to measure safely and accurately.
- Park the vehicle on a flat surface, turn off the engine, and disconnect the battery if you’ll be handling electrical connectors near the throttle body.
- Remove the air intake hose and any sensors near the throttle body to gain clear access to the bore.
- Clean the exterior and the bore area with a clean rag to remove debris that could skew measurements.
- Use a digital caliper to measure the internal bore diameter at the widest point of the circular opening. Take multiple measurements around the circumference and average them for accuracy.
- Record the measurement in millimeters. This value is the throttle body bore size and is the primary metric for compatibility checks.
- Cross-check this value against OEM data, service manuals, or retailer catalogs to confirm the exact model and compatibility with your intake manifold and sensors.
Note: Some engines have a multi-throttle or dual-bore arrangement. In those cases, you may have more than one bore size per engine, and each bore must be measured for precise matching with its corresponding intake port or throttle body module.
Where to Find Official Specs and Quick References
Official documentation and reputable parts catalogs are the most reliable sources for throttles sizes. Use these resources to verify the bore size and compatibility before ordering parts.
- Vehicle owner's manual and service manual from the manufacturer.
- OEM parts database accessible via the manufacturer’s website or dealer portal using the VIN or engine code.
- Authorized parts catalogs and cross-reference guides from reputable aftermarket vendors.
- Dealership service department or a certified mechanic with access to OEM data.
Relying on primary sources reduces the risk of ordering a mis-sized throttle body, especially for drive-by-wire systems where sensors and electronic calibrations must align with the unit.
Summary
To determine your throttle body size, locate the bore diameter by measuring with calipers or pull the exact part number from the unit and verify it against OEM specs or the vehicle’s VIN-based catalog. Use multiple verification methods to avoid mismatches and ensure proper fitment with the intake manifold and sensors. When in doubt, consult a dealer or qualified technician for confirmation.
