And such systems like that…
wouldn’t a cylinder not firing (or 4) put a VERY large amount of stress on the crank?
Or am I just not understanding how it works?
My thoughts : 8 cylinders firing.
You now coast.
4 cylinders shut off. IE. vavles open and close but no fuel is let in and spark plug doesn’t fire.
I think that’s the general jist of it, can someone elaborate?
i always wondered what the real world fuel economy is for vehicles that utilize this technology - like the new Hemis for example…
no more then with all 8 running, balance is key. that tech is going to be happening more and more. i was just talking aboiut this at work. soon ka’z will have 2 engines. One “pony” motor for mpgz and "hall ass’ motor.
my thought
http://www.allpar.com/mopar/new-mopar-hemi.html
Scroll down to where it says “Displacement on demand”
very different from the old caddy 4-6-8
This would be fairly inefficient.
The only stress is the weight of the piston/rod assembly, minimal compression resistance, and the friction involved with it going up/down in the sleeve and any pin/bearing related frictional loses. With DOD the oil passages for the deactivated cylinder is blocked off by a soleniod thus collapsing the hydraulic lifters and eliminating the valves from opening. This basically leaves the cylinder with little air in it and you get a yo-yo effect from the air compressing/expanding. I certain the crank experiences stresses that are 1000X greater during the normal combustion cycle so having half shutdown is minimal.
:gotme: can u supercharge the pony?
halas can sum it up best, for gods sake he’s a gm engineer
I always wondered if they could do this with the ferrari/lambo style engines where each bank of cylinders operates as a seperate engine connected to the same crank (at least thats the way I understand it). Like if one whole side could be shut down until needed.
didnt work back in the day with caddies, wont work now
Why won’t it work now? Back than wasn’t it a primitive electronic fuel injection? Like an 8 bit processor. Now the ECU is much more powerful, and able to calculate what it takes to activate/deactivate a bank of cylinders.
this is true…
idk, just felt like bein an ass
^ :roll2:
My understanding is similar to Halas’ post above. It has evolved along way since introduction and will be making it’s wayinto more applications.
I didn’t know that closing off the lifters was how it was done tho… wow.
or they could just use small 4 bangers with vtec and terblows 
i keed i keed, dod and further advances in this technology are sweet :tup: