A question about the new HEMI and MDS

2002 Views 9 Replies 7 Participants Last post by JSA 007, Jul 20, 2005

carchitect

Discussion Starter · Jul 15, 2005

Hey everybody this is my first time posting at these forums, which are quite nice btw.

I've been reading up on the new HEMI quite a bit lately, more specifically MDS, but I haven't found out too much other than that it turns off 4 cylinders when the engine is not under load.

This question is more to satisfy technical curiousities more than anything. But I was wondering if MDS when activated (by that I mean 4 cylinders running, and four off) would cycle through the avaible 8 cylinders. By that I mean does MDS alternate which 4 cylinders recieve power during a stroke of the engine, or does the engine simply turn off the SAME 4 cylinders everytime MDS is activated.

Thanks for any insight
-Manris

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CO-Charger

· #4 · Jul 15, 2005

Manris said:
I know the cylinders don't shutoff, but they aren't supplied with the means to make power... they aren't supplied with fuel and a spark, but air does pass through them.

Actually, the system deactivates the valves and they remain closed. Any air/fuel that is "caught" in the cylinder is compressed and recompressed over and over, this creates a "spring" action that helps keep the pistons moving. Most likely there is also some factor of blow-by (air/fuel mix seapage past the rings) but probably very minimal. Since the computer shuts the spark off there is no ignition.

BTW - Welcome to the forum.

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