tooter's manifold adventure...

[Bluevitz-rs]

Originally Posted by tooter

Well... maybe.

Although hybrids use an Atkinson cycle engine which is quite different from regular Otto cycle engines. Atkinsons fire once per revolution, whereas Ottos fire once for every two revolutions.

I think you're confusing it with a 2 stroke. Atkinson cycle is the same as Ottos. The only difference is that Atkinson has a shorter compression stroke than power stroke. On the Prius, this is achieved through intake cam timing and duration. The intake valve is held open much longer allowing some of the intake charge to be pushed back on the compression stroke reducing the energy required to compress the intake charge. This in turn rises the efficiency of the engine by effectively making the power stroke longer extracting more energy.