What size is the throttle body of a k20?
The stock throttle body bore for most K20 engines is 70 millimeters, though there are variations by model and year. In practice, 70 mm is the size you’ll most often encounter, but the exact size depends on the specific K20 variant and production revision. This article explains what you’re likely to see and how to confirm your exact size.
Stock bore: what you’re likely to find
This section outlines the general rule of thumb for factory throttle body sizes on K20 engines. While 70 mm is the common baseline, it’s important to verify for your exact build since some variants and market editions can differ.
- Typical stock bore is 70 mm for the majority of K20A/A2 and K20Z-series engines.
When planning upgrades or replacements, always confirm your specific engine code and year to ensure compatibility with the throttle body you intend to use.
How to verify your exact size on your vehicle
To identify the precise throttle body bore for your K20, use one or more of these verification methods:
- Identify your engine code and production year from the VIN, engine bay stamping, or owner’s manual.
- Consult the official Honda/Acura service manuals or OEM parts catalogs for your exact model and year to confirm the throttle body bore.
- If needed, physically measure the bore with calipers (measure the inner diameter of the throttle body opening, not the outside) to determine the bore size.
- Check the throttle body or intake manifold part number. Cross-referencing the part number with official diagrams or catalogs can reveal the bore size and compatibility.
- When in doubt, contact a dealer or a reputable shop to verify your build’s specifications.
Accurate identification ensures you source correctly sized replacements or upgrades and avoid mounting or calibration issues.
Notes for upgrades and tuning
When upgrading a K20 throttle body, consider how bore size interacts with intake manifolds, throttle-by-wire control, and ECU tuning. A larger bore can increase airflow but may require recalibration and supporting changes elsewhere in the air-handling system to realize gains and maintain drivability.
Summary
In most K20 engines, the factory throttle body bore is 70 mm, but exact size can vary by variant and year. To be certain, identify the exact engine code and consult official sources or measure the bore directly. This ensures you pick the right part for replacements or upgrades and avoid compatibility issues.
What size is the RSX type-S throttle body?
The stock RSX Type-S throttle body is a smaller diameter, but aftermarket options are commonly available in sizes like 70mm and 72mm for increased airflow, with some performance builds opting for even larger 74mm or larger throttle bodies. These larger throttle bodies often require matching intake manifolds to ensure proper fitment and can necessitate engine management tuning for optimal performance.
Stock vs. aftermarket
- Stock: The stock throttle body on an RSX Type-S is smaller, with aftermarket options providing significant airflow upgrades.
- Aftermarket: Common aftermarket sizes are 70mm and 72mm, but 74mm and larger are available for more aggressive builds.
Considerations for aftermarket installation
- Intake manifold: A larger throttle body will likely require you to either use a compatible intake manifold or modify your existing one to match the new throttle body's bore and passage size.
- Tuning: After installing an aftermarket throttle body, engine management tuning (such as with K-Pro) is highly recommended to ensure the engine runs correctly and to take advantage of the increased airflow.
- Other components: You may also need to replace other components like the throttle cable to ensure proper length and function with a larger throttle body.
What cars have the J37 throttle body?
Honda/Acura J37 Throttle Body (DBW) - ZDX / MDX / 06-15 Civic Si - JHPUSA.
What size is the throttle body on a K20A2 stock?
In fact, all of the following engines have OEM 62mm throttle bodies: K20A (JDM RSX Type-R) K20A2 (RSX Type-S 02-04) K20A3 (RSX Base)
How to figure out throttle body size?
I've always used the calculation formula: Engine displacement/number of cylinders x rev limit.. (For the calculation above the constants Being the 0.8 is based on VE avarage at peak for most N/A engines, and the 0.5 being of VE avarage at idle.) So 44mm throttle body be about your ball park to consider.
