At most of the tracks I race in the mid-west you have two fuel options. Sunoco Standard (leaded 110 octane) and an unleaded gas, SS100 I think. I'm old school and wanted to use a leaded gas in my 4 stroke racer. Could probably use the unleaded fuel in my two stroke race bike though. Here is what Sunoco says about these fuels:
Sunoco® Standard™ is a 110 octane leaded race fuel that is used in many forms of motorsports. Sunoco Standard is designed for compression ratios up to about 13:1 in conventional V8 engines with iron cylinder heads. It can tolerate higher compression ratios in aluminum cylinder head applications or engines with smaller or more efficient combustion chambers. While most racers use Sunoco Standard in naturally aspirated applications, it is also a good choice for mild nitrous, turbocharged, and supercharged applications.
Sunoco SS 100 is an unleaded high octane gasoline that is street-legal in California. Its 100 octane rating will allow increased boost levels in supercharged or turbocharged applications compared to premium pump gas. Sunoco SS 100 can be used in high performance vehicles both old and new. It can also be used in applications such as motorcycles, ATVs, karts, and other smaller engine vehicles.
When I started racing in the 70's Sunoco Cam 2 was the fuel of choice, but is no longer available. Here is a link to the Sunoco web site:
http://www.sunocoracefuels.com/fuels