Engine Change Guidelines

According to the California Bureau of Automotive Repair (BAR), “Engine changes continue to present problems and challenges to car owners and technicians“.

Instead of an engine change (a.k.a swap), BAR recommends rebuilding and reinstalling the original engine, transmission, and emissions configuration.  However, if that is not possible, the following is a list of things to keep in mind.

Remember, these are guidelines for performing engine changes – not certification procedures. All exhaust emission controlled vehicles with engine changes must be inspected by an official Referee station and must have a Bureau of Automotive Repair (BAR) Referee label affixed to the doorpost.

Certification Standards

California Certification

emissions-label-caA federal (49 state) engine cannot be used in a California certified vehicle.

You can determine if your vehicle is a California certified vehicle by checking the vehicle’s under-hood emissions label.

Japanese Domestic Market (JDM) Engines

While especially popular with Honda enthusiasts JDM engines are not a legal option.  JDM engines are easily identified and will not be certified by the BAR Referee.

Certification Standards

Make sure the engine and emission control configuration is certified to the year of the vehicle or newer, and to the same or a more stringent new vehicle certification standard. The rule of thumb is that you can move forward but you can’t go backwards.

Engine Classification

Lamborghini engine

You can’t put this in Lamborghini engine in your pickup truck unless you’re hauling it in the back.

Don’t mix engine and vehicle classifications which will degrade the emissions certification standards.

  1. A heavy-duty engine cannot be installed in a light-duty exhaust-controlled chassis even if they have the same displacement.
  2. A Pickup truck engine cannot be installed in a passenger car.
  3. Non-emissions controlled engines such as industrial or off-road-use-only engines may not be placed in any exhaust emissions controlled vehicle.

Computer Controls

If a computer controlled engine is installed in a non-computer controlled vehicle, the “Check Engine Light” (Service Engine Soon, MIL, etc), diagnostic link connector (DLC), wiring harness, and all sensor and switches necessary to make the system fully operational must also be installed.

Also, the same rule would apply if you are installing an On Board Diagnostic II engine in a vehicle previously certified to earlier standards (OBD I etc).  Remember, you can add, but you can’t subtract.

Emissions Control Configuration

Mixing and matching emission control system components could cause problems and is generally not allowed. Engine and emission control systems must be in an engine-chassis configuration certified by the California Air Resources Board (ARB) or U.S. Environmental Protection Agency (EPA). The engine must meet or exceed the requirements for the year and class of vehicle in which it is installed.

California Bureau of Automotive Repair

Vehicles introduced for sale in California and elsewhere in the United States are subject to strict testing and emissions certification standards. Even a minor change can result in the increased harmful gas emissions, and violate state and federal law.

The installed engine and host chassis must retain all original emission control equipment. Diesel-to-gasoline conversions must have all gasoline engine and chassis emission control systems installed (Fill-pipe restrictor, EVAP system, etc).

Engine Modification and After-Market Parts

No internal or external engine modifications (cams, pistons, intakes, etc.) may be performed unless the parts are ARB-exempted or EPA-certified for use in the installed engine. Refer to ARB’s Aftermarket Parts Database of Executive Orders to search for exempted aftermarket parts.

2 Replies to “Engine Change Guidelines”

  1. todd

    As far as engine classifications, why am I not allowed to put a cleaner running passenger vehicle engine in a light duty truck? I understand where this would be a problem if the original engine is cleaner than the donor but it smacks of arbitrary requirements if the rule disregards the cleaner outcome.

    • dewok

      Hi Todd,

      I completely agree with you. I would contact the California State Referee and ask them about your configuration plans. You can visit asktheref.org or call toll free: 1-800-622-7733.

      Just Smogs


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