# Displacement on Demand **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [September 28, 2005, 2:36pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829 "2005-09-28T14:36:09Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Daddie](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/daddie/32/7621_2.png) [@Daddie](https://forums.speedlife.net/u/Daddie)\ **Post date:** [September 28, 2005, 2:36pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/1 "2005-09-28T14:36:09Z")
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? ---
**Author:** ![BubbleSparkxx](https://avatars.discourse-cdn.com/v4/letter/b/a87d85/32.png) [@BubbleSparkxx](https://forums.speedlife.net/u/BubbleSparkxx)\ **Post date:** [September 28, 2005, 2:43pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/2 "2005-09-28T14:43:20Z")
i always wondered what the real world fuel economy is for vehicles that utilize this technology - like the new Hemis for example… ---
**Author:** ![Anonymity](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/anonymity/32/7215_2.png) [@Anonymity](https://forums.speedlife.net/u/Anonymity)\ **Post date:** [September 28, 2005, 3:33pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/3 "2005-09-28T15:33:58Z")
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 ---
**Author:** ![Denton](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@Denton](https://forums.speedlife.net/u/Denton)\ **Post date:** [September 28, 2005, 3:38pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/4 "2005-09-28T15:38:29Z")
> [@Daddie](#): > > I think that’s the general jist of it, can someone elaborate? [http://www.allpar.com/mopar/new-mopar-hemi.html](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 ---
**Author:** ![RedGoober4Life](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/redgoober4life/32/7610_2.png) [@RedGoober4Life](https://forums.speedlife.net/u/RedGoober4Life)\ **Post date:** [September 28, 2005, 3:40pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/5 "2005-09-28T15:40:57Z")
> [@fastandcheap](#): > > 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 This would be fairly inefficient. ---
**Author:** ![halas](https://avatars.discourse-cdn.com/v4/letter/h/898d66/32.png) [@halas](https://forums.speedlife.net/u/halas)\ **Post date:** [September 28, 2005, 6:28pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/6 "2005-09-28T18:28:21Z")
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. ---
**Author:** ![King](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/king/32/7329_2.png) [@King](https://forums.speedlife.net/u/King)\ **Post date:** [September 28, 2005, 6:33pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/7 "2005-09-28T18:33:37Z")
> [@fastandcheap](#): > > 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 :gotme: can u supercharge the pony? ---
**Author:** ![AKA-FERRARI](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/aka-ferrari/32/7260_2.png) [@AKA-FERRARI](https://forums.speedlife.net/u/AKA-FERRARI)\ **Post date:** [September 28, 2005, 7:15pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/8 "2005-09-28T19:15:59Z")
> [@halas](#): > > 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. halas can sum it up best, for gods sake he’s a gm engineer ---
**Author:** ![dozr](https://avatars.discourse-cdn.com/v4/letter/d/41988e/32.png) [@dozr](https://forums.speedlife.net/u/dozr)\ **Post date:** [September 28, 2005, 8:35pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/9 "2005-09-28T20:35:29Z")
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. ---
**Author:** ![turbo\_ls1\_ss](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/turbo_ls1_ss/32/7303_2.png) [@turbo\_ls1\_ss](https://forums.speedlife.net/u/turbo_ls1_ss)\ **Post date:** [September 28, 2005, 8:36pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/10 "2005-09-28T20:36:11Z")
didnt work back in the day with caddies, wont work now ---
**Author:** ![16vCorvette](https://avatars.discourse-cdn.com/v4/letter/1/b487fb/32.png) [@16vCorvette](https://forums.speedlife.net/u/16vCorvette)\ **Post date:** [September 28, 2005, 8:56pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/11 "2005-09-28T20:56:40Z")
> [@turbo ls1 ss](#): > > 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. ---
**Author:** ![STEALTTH](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/stealtth/32/7582_2.png) [@STEALTTH](https://forums.speedlife.net/u/STEALTTH)\ **Post date:** [September 28, 2005, 10:13pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/12 "2005-09-28T22:13:15Z")
this is true… ---
**Author:** ![turbo\_ls1\_ss](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/turbo_ls1_ss/32/7303_2.png) [@turbo\_ls1\_ss](https://forums.speedlife.net/u/turbo_ls1_ss)\ **Post date:** [September 28, 2005, 10:15pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/13 "2005-09-28T22:15:24Z")
> [@16vCorvette](#): > > 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. idk, just felt like bein an ass ---
**Author:** ![Nikuk](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nikuk/32/7254_2.png) [@Nikuk](https://forums.speedlife.net/u/Nikuk)\ **Post date:** [September 29, 2005, 1:44pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/14 "2005-09-29T13:44:21Z")
^ :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. ---
**Author:** ![chino](https://avatars.discourse-cdn.com/v4/letter/c/bcef8e/32.png) [@chino](https://forums.speedlife.net/u/chino)\ **Post date:** [September 29, 2005, 1:57pm UTC](https://forums.speedlife.net/t/displacement-on-demand/2829/15 "2005-09-29T13:57:30Z")
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: