What is MDS?

**yitbos_magnum** · 01-08-2009, 05:50 PM

I keep seeing MDS mentioned, but I have no idea what it is.

Perhaps it should be added to the list of acronyms, I didn't see it on there.

**JarZ** · 01-08-2009, 05:52 PM

Multi-Displacement System

the 5.7L Hemi has MDS which makes it able to run on only 4 cylinders under light load/highway driving to conserve fuel.

**higshemi-less** · 01-08-2009, 05:53 PM

Multi-Displacement System, Its a term coined by Chrysler to refer to the engine management shutting down half the cylinders when crusing or no load on the engine. Primarily used to save gas.

**Alfa Charger** · 01-08-2009, 05:53 PM

Originally Posted by yitbos_magnum

I keep seeing MDS mentioned, but I have no idea what it is.

Perhaps it should be added to the list of acronyms, I didn't see it on there.

The Hemi features cylinder deactivation in the 300C and Magnum R/T; the "Multi Displacement System" (MDS) turns off the fuel consumption in four cylinders when V-8 power is not needed. This provides a world class combination of performance and fuel economy, without the driver noticing any difference. The MDS system has, according to Chrysler, saved nearly 100 million gallons of gasoline since 2005, and reduced carbon dioxide (CO₂) emissions by close to a million metric tons.

**Magnum Power** · 01-08-2009, 06:33 PM

Originally Posted by Alfa Charger

The Hemi features cylinder deactivation in the 300C and Magnum R/T; the "Multi Displacement System" (MDS) turns off the fuel consumption in four cylinders when V-8 power is not needed. This provides a world class combination of performance and fuel economy, without the driver noticing any difference. The MDS system has, according to Chrysler, saved nearly 100 million gallons of gasoline since 2005, and reduced carbon dioxide (CO₂) emissions by close to a million metric tons.

I wounder if that makes the 5.7 Hemi a green car?

**higshemi-less** · 01-08-2009, 06:35 PM

My type of Hybrid

**NC-SXT** · 01-08-2009, 06:59 PM

Originally Posted by Higshemi

My type of Hybrid

You do have a hybrid.....V8 and a 12 volt battery

**yitbos_magnum** · 01-08-2009, 08:28 PM

Thanks for the answer, although now I have another question:

People seem to be keen on turning off the MDS with the Predator module - why would you want to do this? I haven't noticed any sort of lag when driving that would make me want to sacrifice the gas mileage savings. What is the positive benefit of disabling the MDS with the tuner modules? And how much is gas mileage really suffering as a result?

**Magnum Power** · 01-08-2009, 08:38 PM

A lot of folks turn off MDS because they have an exhaust system that has a drone to it when MDS is active. Turning it off makes it sound better.

**done** · 01-08-2009, 11:23 PM

Originally Posted by yitbos_magnum

Thanks for the answer, although now I have another question:

People seem to be keen on turning off the MDS with the Predator module - why would you want to do this? I haven't noticed any sort of lag when driving that would make me want to sacrifice the gas mileage savings. What is the positive benefit of disabling the MDS with the tuner modules? And how much is gas mileage really suffering as a result?

Originally Posted by Magnum Power

A lot of folks turn off MDS because they have an exhaust system that has a drone to it when MDS is active. Turning it off makes it sound better.

Yup, that is most common silly reason.

Probably the only real reason to turn it off is when the special MDS lifters are replaced with regular lifters to support a higher lift cam.