Forum:Top speed, Power Plants

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since watching the movie Speed Racer i have wondered these vehicles top speeds and power plants. while it seems that some cars are powered by internal combustion engines and Turbo jet/scram jet engines hybrids. it seems that other cars are just powered by internal combustion or jet engines. the Mach 6 has a gear shift and it rev's something thats not possible for a jet engine to have as the car would be moved by the exhaust of the jet and if it could growl like an engine that would mean the brakes would have to hold the car still instead of having the car out ofgear or in neutral. but the rear of teh car clearly shows a jet engine exhaust. meaning the car is some how powered by both. and what would these cars top speeds be 300+? give me your thoughts. one last thing what kind of horsepower would these cars produce there is nothing on the net giving any of this info