dumb question : running w/o transmission
 

is it stupid to run the engine without the transmission installed?

I imagine removing all that resistance to the drive shaft could lead to excess rotation.

Not a problem, just don't expect to get anywhere very fast.

lol - won't matter. you won't be going anywhere without the trans

seriously though, engine dynos don't use transmissions, and they spin those suckers up all day long

The flywheel attached to the engine controls how quickly the engine spins. Without the transaxle, the engine is spinning just like it is in neutral.

The torque tube might walk. I would not do much of this.

If it is short durationy, you could always disconnect the torque tube to the engine by pushing down on the clutch.

If you had just an engine but no transmission and drivetrain, you'd need to push your car even though the engine runs :p If you have an engine and a drivetrain, but no transmission, you wouldn't have enough torque to move sufficiently since the drivetrain wouldn't be geared down.

On the bright side, without the transmission, your car would weigh less :p