KyleT said:
it is the blackest murkiest grey area there is...
http://www.epa.gov/compliance/resources/policies/civil/caa/mobile/engswitch.pdf
it falls into the states hands as far as I can tell.
This is why you need to get in touch with your DEQ is important. Forget the DMV, they control registration, not inspections. Northern Virginia is a completely different state than the rest of Virginia. We do intensive testing, the rest of the state, not so much. When I asked my DEQ, the Director by the way, this is the response I got:
"Vehicle emissions certification is controlled under Federal law. Federal regulations control tampering with or altering any vehicle emissions configuration. These regulations have become stricter as vehicle emissions controls have become more effective and more complicated. In general engine swaps (and presumably gasoline engine to diesel engine) are allowed only if they conform to a configuration that was certified for the newer of the chassis or the engine year. See EPA fact sheet attached. If a diesel configuration has not been certified for your vehicle chassis EPA would require extensive testing.
Also Virginia regulations (9VAC 5-91-490) stipulate that the emissions standards for the year & model of the vehicle chassis or engine, whichever is newer, apply for the emissions inspection program. Diesel vehicles up to 8500 lbs gvwr are required to pass an on-board diagnostic emissions test in the northern Virginia area. If either the engine or the chassis is 1997 or newer, this would apply to your vehicle.
If the vehicle is 1996 or older, if it diesel you would not be prompted for an emissions test. In this case, if designated as a diesel, an emissions inspection would not be required. I am not sure what DMV requires with respect to changing the fuel type on your vehicle record."
Excerpts from the above referenced EPA Engine Switching Fact Sheet:
"EPA received many questions regarding the application of this law to a situation where one engine is removed from a vehicle and another engine is installed in its place. EPA's policy regarding "engine switching" is covered under the provisions of Mobile Source Enforcement Memorandum No. lA (Attachment 1). This policy states that EPA will not consider any modification to a "certified configuration" to be a violation of federal law if there is a reasonable basis for knowing that emissions are not adversely affected. In many cases, proper emission testing according to the Federal Test Procedure would be necessary to make this determination."
"A "certified configuration" is an engine or engine chassis design which has been "certified" (approved) by EPA prior to the production of vehicles with that design. Generally, the manufacturer submits an application for certification of the designs of each engine or vehicle it proposes to manufacture prior to production. The application includes design requirements for all emission related parts, engine calibrations, and other design parameters for each different type of engine (in heavy-duty vehicles), or engine chassis combination (in light-duty vehicles). EPA then "certifies" each acceptable design for use, in vehicles of the upcoming model year.
For light-duty vehicles, installation of a light-duty eng~ne into a different light-duty vehicle by any person would be considered tampering unless the resulting vehicle is identical (with regard to all emission related parts, engine design parameters, and engine calibrations) to a certified configuration of the same or newer model year as the vehicle chassis, or if there is a reasonable basis for knowing that emissions are not adversely affected as described in Memo 1A. The appropriate source for technical information regarding the certified configuration of a vehicle of a particular model year is the vehicle manufacturer."
"The most common engine replacement involves replacing a gasoline engine in a light-duty vehicle with another gasoline engine. Another type of engine switching which commonly occurs, however, involves diesel powered vehicles where the diesel engine is removed and replaced with a gasoline engine. Applying the above policy, such a replacement is legal only if the resulting engine-chassis configuration is equivalent to a certified configuration of the same model year or newer as the chassis. If the vehicle chassis in question has been certified with gasoline, as well as diesel engines(as is common), such a conversion could be done legally.
Another situation recently brought to EPA's attention involves the offering for sale of used foreign-built engines. These engines are often not covered by a certified configuration for any vehicle sold in this country. In such a case, there is no way to install such an engine legally. EPA has recently brought enforcement actions against certain parties who have violated the tampering prohibition by performing illegal engine switches."
Read and decide for yourself. There is also this part about the State laws at the end:
"B. State Laws
Many states also have statutes or regulations prohibiting tampering in general. Most of these laws specifically prohibit tampering by individuals. A few specifically prohibit engine switching, using provisions similar to those stated in EPA's policy. To determine the state law in any given state, the state's Attorney General's office should be contacted. In addition, many states have state or local antitampering inspection programs which require a periodic inspection of vehicles in that area, to determine the integrity of emission control systems. Many programs have established policies for vehicles which have been engine switched. While EPA does not require these programs to fail engine switched vehicles which are not in compliance with federal policy, the Agency does strongly recommend that these programs set their requirements so as to be consistent with the federal law. State or local programs which pass illegally engine switched vehicles may mislead federally regulated parties into believing that engine switching is allowed by federal law.