I have a good idea for a linear actuated drive system for automobiles and engines in general. I need a recommendation for a linear actuator that has a stroke of up to 18 inches, can perform very fast cycles of actuation and retraction in a controlled fashion, around 25 to 50 Hz. Needs to provide 100 lbs up to 500 lbs force onto shaft. Should be adjustable/controllable in terms of amount of force and cycle rates. I am looking currently for a low cost actuator with theses properties. If it works, you will be the second person to own a fairly sporty airpowered car. Air/pneumatic or electromechanical actuator doesn't matter to me. Please help the world get off the Oil Industry stranglehold. Thanks.