You can thank the US EPA for the extremely limited amount of alternative fuel conversion kits being on the market today in North America. Before the EPA became so heavily involved with requiring conversions to comply with ever tighter emission requirements, propane conversions were a relatively straight forward affair. While never really a bolt-on upgrade suited to the backyard mechanic, a propane conversion was simple to do. Emissions weren't a problem because a propane-fuelled car would have better emissions than the same gasoline-fuelled, carbureted car. As a result of these EPA regulations, a huge number of companies went out of business or had to radically change their business plan. The installation of a non-certified system can be considered as "tampering" by the US EPA and CARB, which implies that universal systems are only recommended for off-road use.
The only kits available today to the backyard do-it-yourself mechanic are for off-road applications. A few companies offer DIY kits but these are often tailored to a very limited number of pre-1986 off-road vehicles. Technocarb currently offers both bi-fuel conversions for fuel injected gasoline vehicles and dual-fuel conversions for diesel vehicles. For current model year vehicles, kits are available for the fleet owner and these kits are generally tailored to a very limited number of fleet-suitable vehicles such as the Ford Crown Victoria and Lincoln Town Car.
Other than us, there are very few suppliers that provide propane conversions for modern fuel-injected vehicles and this is mainly because there are very few EPA and/or CARB-certified systems available. Many available DIY conversion kits are for carbureted vehicles or vehicles that have been downgraded from EFI to carburetion. Generally, even if these vehicles no longer require emission inspections, older carbureted on-road vehicles must continue to have all emission controls in place and fully functional. Shops that convert a vehicle with non-certified system may potentially be liable to penalties from the EPA or other authorities. However, shops are permitted to repair uncertified systems without risk of penalty.
Even though a properly configured injection conversion will run cleaner than the original gasoline engine, the lack of certification for universal systems means that they are generally non-compliant and are therefore recommended for "off-road" use only . Besides our own e-commerce site, the following sites offer DIY propane conversions for older carbureted vehicles only:
Before you buy any system, discuss your project with a local propane conversion company first for the following reasons:
- You should have your conversion inspected to that it meets propane safety codes in your jurisdiction and it best to work closely with the company that will be inspecting your work.
- If you experience any technical difficulties, they will be better able to assist you.
- They will be able to give you advice as to what systems meet emission regulation in your area. In the USA, the installation of a non-certified system may not comply with EPA or CARB regulations.
Propane fumigation systems have been used to convert EFI engines but fumigation conversions work best on carbureted systems. We have propane injection conversions for TBI engines and these systems work very well. They do not generate CELs and propane operation is invisible to the driver.
Fumigation conversions were also used on MPFI engines before propane injection systems were readily available. However, they never worked very well and were often prone to intake manifold backfires. Impco-based fumigation conversions also relied on Dual Curve for "fixes" that allowed the vehicle to run properly and not have CELs but their products are now obsolete. Although propane injection conversions are slightly more expensive than fumigation conversions were, injection conversions offer better fuel economy and reduced maintenance, which have a faster payback in the long-run. Fumigation systems also had difficulty meeting emission regulations.