Engine Swaps Made Easier
Those engaged in engine swaps are bound by specific state laws that vary from state to state, but there are some general guidelines to consider. Here we'll cover the basic rules for swapping the engine in production vehicles (but not specially constructed vehicles, street rods, kit cars and the like). The basic rule of engine swapping (as opposed to installing a "replacement" engine) is the change must do no harm. This means that the engine being installed must theoretically be at least as "clean" as the one taken out. Several requirements define "clean" for the purposes of engine switching:
Model Year The engine to be installed must be the same age or newer than the one being replaced. Crate engines can be used if they are configured to resemble an engine that was certified by the EPA and/or CARB. This essentially means the required emissions parts must be installed.
Certification Level The engine to be installed must come from a vehicle certified to meet the same or more stringent emissions standards than the one replaced.
Vehicle Class An engine from a vehicle class such as a motor home, medium-duty truck or marine application must not be used since these engines were certified to different emissions standards.
System/Equipment When swapping in a newer engine from a later-model vehicle, all of the relevant emissions control equipment must be transferred as well. This includes the carbon canister, catalytic converter(s), and even parts of the on-board diagnostic (OBD) system. Some states have exceptions to this, but the general rule is that as much of the donor vehicle's emissions system as possible should be transferred. The vehicle will likely run more efficiently with a full transfer of the system, and shouldn't cause any undue heartache.
The U.S. EPA and many states have enforceable policies and guidelines on how to perform legal engine changes. For further information, please consult the EPA and California Bureau of Automotive Repair.
Exhaust Noise: How Loud Is Too Loud?
Imagine driving down the road and getting stopped for the exhaust on your restored '74 Nova. Now imagine sitting on the shoulder, receiving a citation from local law enforcement, while a stock Ferrari overtakes your car and drives on. This is the scene being played out across the country, the result of poorly drafted or ineffective state laws and regulations. The laws on the books frequently cite the manufacturer's specifications or a factory installed muffler as the basis on which vehicle exhaust noise is measured.
On this, states can generally be divided into two major categories: states with noise standards, and states without noise standards. Of the states with a test standard on the books, many ignore guidelines when handing out citations. Most states that have chosen to go the route of setting specifications choose to measure a vehicle's noise by decibels. States that have quantifiable noise standards on the books are shaded red in the map below. These standards often go unenforced. One reason is they are based on an in-use standard-exhaust noise is measured while a vehicle is in motion on the highway.
Other states choose not to specify a measureable noise standard. These states are shown in yellow in the map above. Typical language in these states' statutes includes prohibitions on "excessive or unusual noise" from a vehicle's exhaust system. While most motorists believe exhaust systems should not be used in a way that causes overly loud or objectionable noise, these vague provisions fail to provide a clear and objective standard for those seeking more durable exhaust systems that enhance a vehicle's appearance and increase performance.
Language that effectively limits the use of aftermarket exhausts can be found amongst both yellow and red states. Such language includes sentences like "no person shall modify the exhaust system of a motor vehicle in any manner which will amplify or increase the noise or sound emitted louder than that emitted by the muffler originally installed on the vehicle." While such language does not specifically prohibit all modification, it does not provide any means of measuring whether a vehicle has been acceptably modified. Such language also negatively affects the aftermarket industry by placing the noise limit authority in the hands of the OEMs and ignores the fact that aftermarket exhaust systems are designed to make vehicles run more efficiently without increasing emissions.
Green on the map identifies states with SEMA model legislation to provide enthusiasts and law enforcement officials a fair and enforceable alternative. The model legislation establishes a 95-decibel exhaust noise limit based on an industry standard adopted by the Society of Automotive Engineers (SAE). Under this standard (SAE J1169), a sound meter is placed 20 inches from the exhaust outlet at a 45-degree angle and the engine is revved to three quarters of maximum rated horsepower. The highest decibel reading is then recorded.