Both valves couldn't stay closed. The closed cylinder would compression brake the engine. Both valves couldn't stay open. That would pump air into the exhaust and confuse the O2 sensor. Most likely, the intake would stay closed and the exhaust would stay open. Unless there was a separate compression release like old motorcycles had for kickstarting but nothing like that is mentioned.

 

The article explains that

"In order to eliminate the pumping losses," says Meagher, "you need to disable both the intake and exhaust valve." This results in a completely sealed, deactivated cylinder, which is essentially an air spring being acted upon by a piston. Virtually all the work put into it during compression is returned to the crank during decompression, finally giving credence to the old joke about piston-return springs. (That's nothing. Wait 'til you hear about the muffler valve...)

"Currently, we could disable just the fuel delivery," says Meagher, "but the valves would still be opening and closing and each cylinder would still be doing work pumping air in and out. So there would be no net gain in efficiency--you wouldn't have eliminated the pumping losses at all."

 

Now that this has been explained here, I'm wondering waht happens to the oil that gets by the rings during a DOD cycle?
Is the amount so small that it does not affect that cylinder once it goes back to V8 mode?
Or is there absolutely no oil getting up past the top ring?

I know oil is not supposed to get to the top of the cylinder if all your rings are doing their job but you would think that some residual amount would and not be burned off like a normal motor would do.

Maybe I'm talking out the wrong hole here.

 

I agree with you here TG. Always wondered that myself. Cyl combustion aids in the sealing of the rings to scrape the oil away and down the cyl bore. With no combustion, the rings don't "Puff" out like they should and don't scrape as aggressivly. Have they switched to a newer high tension style oil scraper ring on the new DoD motors?

 

DOD has its own cylinder block, it bleads the oil pressure out of the lifters

 

The new GM V8's have lifter bleed off?? How is this mechanically possible?