DIY displacement on demand system project

[itjstagame]

It twinning the O2 sensors together doesn't work you could at least trigger open mode my removing or setting the coolant temp sensor low (depends on vehicle). This should be better than limp home mode.

As for the rest of it, definately I3 should be ok because most V engines share opposite banks on the same spot of the crank (I say most because I don't think the VR6 engines do), but definately stay away from I4. Lateral force (that is unbalanced perpendicular to rotation) would be very bad and potentially bend the crank.

For the rest of the idea, my friend thought once of somehow installing a valve in the spark plug hole so you could decide when to remove compression. I think the best way would be to add another valve in the head that wouldn't interfere with the piston that you could open either with cable or electromagnets or whatever. I think best would be to hook this to a central plenum between all 'dead' cylinders and then as one went up another would come down and all pressure forces should cancel and wouldn't pull fresh air or pull on exhaust flow but would eventually cool down and may cause the other issues mentioned by others.

The other thought would be to somehow drop out the compression and power strokes and just always intake-exhaust-intake-exhaust. This provides no compression, but causes issues with fresh air in the exhaust and it would be pretty hard to do, you'd need two cam profiles.

I am really curious if it's even worth it though. It just doesn't make sense to me that compression without ignition would cause much of a loss. As said before it's basically a spring, any time spent compressing is returned on the power stroke. I feel like the biggest loss (at least the biggest drag when turning by hand) is the valve train. Next would be friction and last would be compression.

If I fully seal my valves and install the head I can still spin the crank on my CRX very easily but it's a real pain to spin the camshaft.

I've always wanted to explore a rotary or electric valve system but that's a whole nother discussion.