351W 4V in 1969-70 Technical Forum Posted October 8, 2019 · Report reply I don't drive my Mach 1 much so I don't mind mixing Torco Accelerator with the fuel. I never intended on driving the car much as I was building it. The motor behaves just fine with this mixture. Before using the Torco Accelerator I did use straight 91 octane pump gas. It ran fine, but seems to have more power with the Torco Accelerator mixed in. If you plan on driving the car a lot I would definitely consider a slightly lower static CR so you don't have to worry so much about fuel or additives.