91_z28_4me

There are hollow chambers in the pushrods of the engines. The pushrods extend under hydrostatic pressure from oil pushed at high pressure into the chambers. The chamber/pushrod collapses when the oil is not in the pushrod chamber. The valve closes and the combustion chamber acts as an air spring.

Camaro25thann

I want to make a point that I haven't seen yet in the thread. It seems there are a lot of people worried what the car will sound like at idle, and this is definetly something to be concerned about. However one person stated that DOD doesn't activate under 25 mph. The thing that keeps running across my mind is the unveiling video. When Lutz drove it out onto the floor. I know it was hard to hear over that music, but that exhaust note sure sounded like pure V8 to me. I know he wasn't driving any faster than 2mph, so it may as well have been idling. I don't think GM would be stupid enough to give us back our muscle car, and have it sound like a civic. Go watch the intro video again and listen carefully! Factory V8 rumble is back!

RussStang

I wonder how RPM friendly the whole DoD setup is? It doesn't sound like the pushrods are. Everyone seems to think that DoD is a gimme, with no detrimental effects to performance, but I distinctly remember team Corvette saying that the LS2 did not feature DoD because it would have cost them revs, and with revs go power.

Z28Marcus

I don't think eveyone is that naive. But yes, as I recall the HEMI version of DOD is absent from the top dog 425 HP motor also (someone correct me if I am wrong).

Like all technology, it gets better with age. I'm sure GM isn't resting on their laurels wrt to DOD and 2009 is a way off.