Depending on the car, nothing is necessary normally. Some cars and trucks will need the carb re jetted one or two sizes larger, computer controlled cars seem to adapt on their own to the more octane of alcohol, but some will require a eprom re-flash (available from tons of performance companies). Most small equipment requires the carb to be adjusted and re jetted, nothing more. Most cars are just fine running on alcohol, no parts break more, or wear out faster, no fuel line issues and no catalytic converter issues.
There are some cars that don’t like alcohol but about 99% of them will run perfect with 190 proof spirits. To be honest their is no real “guide” to how this is done, it is an experiment every time. Some engines will require a little more “tuning” than others, it is a seat of the pants type thing, because it is so new.
If you are trying to start converting cars and trucks and equipment around the house, here is how to start.
1) Start small, the smallest engine you have is normally the cheapest to test on.
2) Start with a 50/50 mix of alcohol and gas, then move down the percentage of gas until it is either pure alcohol or runs really terrible. That is the starting point for “conversion”
2A) If it runs good on 190 proof pure, check the plug(s) after 15 minutes run time, then every hour until 2 hours run time is reached. If the plugs appear normal, conversion complete, if not check “2B” below
2B) Anything less than “pure” or 190 proof and runs bad. Check the plugs for a “lean” condition (most likely). Now you must adjust the jet size on the carb, start small sometimes a tiny change is all that is needed. Normally one full jet size is plenty to richen up the fuel air mixture. You can drill them out, normally a #57 drill bit works on most small engines.
3) Monitor engine temp (both on gasoline and alcohol) it should be reduced at the exhaust outlet on the motor, as alcohol burns cooler. If it is hotter than gasoline it is running lean
Once you have completed your first “test” engine you should now start to understand the alcohol fuel system and its characteristics, we now need to try something larger. Maybe a twin cylinder lawn mower? Perfect.
1 and 2 are the same exact steps, just doubled for the spark plugs, also on larger engines test operating temp on gasoline and alcohol, alcohol should run cooler, unless it is in a lean condition which will cause excess heat. Most twin cylinder engines use two pipes connected to feed the exhaust to the single muffler, do not check muffler temp. Check the exhaust temp on each connecting pipe. One cylinder may run leaner than the other.
If everything is in spec and running, conversion complete.
By now after playing around with small engines you should be able to “convert” any engine you feel like, just remember to start with mixed fuel and test from there.