First let me say I don't know much about engine theory other than the basic 4-stroke cycle. I'm sure there's a reason for why no manufacturer is doing this because it sounds too easy.

Why not lengthen the combustion cycle to something like 6 or 8-strokes instead of 4? The extra strokes would be another intake and exhaust. The idea is to reduce the number of times a cylinder fires during cruising only when you only need enough torque to overcome wind resistence. This feature would be activated by the driver or automatically engaged when the cruise function is used.

Or, only run the engine off 2 cylinders and alternate the cylinders every-so-often so some don't take more abuse than others. Same idea as above - produce less power when you don't need it and save fuel.

Why aren't things like this looked into more? Are ideas like this practical, or is there something wrong with them? I don't see why engines can't have a "sleep" state where it only runs enough to keep the accessories going and counter drag. To me, it seems these ideas would be simpler than including a very high gear (low ratio) in the transmission. What do you guys think?

 

A lot of cars do this.

 

:werd:

There's a bunch of companies that offer technology like the ones you mentioned.

 

Guess I'm just in the dark about all this. What are some cars that are doing this? Is there a name for this feature?

 

The new Honda Odyssey, and I believe a Ford product does too like the Mustang or GT

 

Making a 6 or 8 stroke engine is going to be very inefficient and you're going to have terrible pumping losses.

Honda has VCM for cylinder deactivation...GM (DoD) and DCX also have systems. It's been around since the 80's in the Cadillac V-8-6-4 which likes to shut its cylinders off whenever it pleased and in whatever quantity it wanted. Plus it was jerky as all hell. What a disaster.

 

I think that the Chrysler 300c has the cylinder deactivation, as well as a prototype Jeep they are toying with.