MDS question

[rking300]

I'm sure this has been beat to death, so I apologize.
Other than sound with new exhaust (which doesn't concern me much).
What's the benefit of turning the MDS off? How's it changes MPG? etc. etc.

 

[bigdodge]

I'm sure this has been beat to death, so I apologize.
Other than sound with new exhaust (which doesn't concern me much).
What's the benefit of turning the MDS off? How's it changes MPG? etc. etc.

what's the benefit, peace of mind in my opinion.

https://www.jdpower.com/cars/shopping-guides/cylinder-deactivation-how-it-can-save-fuel#:~:text=Rather%20than%20cut%20off%20fuel,supplied%2C%20causing%20gasoline%20to%20accumulate.

 

[theblet]

It helps a bit, but not life changing by any means.

When you’re cruising at 35 to 50 mph you’ll see instant MPG around 30. Also saves fuel when slowing down, or coming down a hill.

 

[Boatman22]

How do you turn the MDS off?

 

[Willwork4truck]

I use the paddle shift to do that. Then make sure its back to “8”. Costs appx 1.5 mpg on my drives.

Theres several YT vids that claim the hemi block has oiling issues with it off.

I’m sure you will get about as much agreement/disagreement on it’s benefits as when we discuss, uhh, oils.

 

[theblet]

How do you turn the MDS off?

You can temporarily disable it by setting the manual gear selector to 8, or using tow haul mode.

Permanent disable required changing the camshaft and lifters, (and a custom tune i suppose.) Don't think many go this route.

 

[mikeru82]

I'm sure this has been beat to death, so I apologize.
Other than sound with new exhaust (which doesn't concern me much).
What's the benefit of turning the MDS off? How's it changes MPG? etc. etc.

There's a lot of opinions on this and not much actual data to back those up. Some claim to save fuel when leaving it enabled, while others claim it makes no difference. I would ignore any YT videos out there with oiling issue claims, as there is again no actual data to support those claims. Just opinions. If it doesn't bother you to leave it on, then by all means leave it on. If you don't like the idea of your v8 engine running on 4 cylinders then by all means disable it. In my experience it doesn't benefit or hurt the engine either way. I've always disabled MDS on my trucks, but the wife lets it do its thing on hers. Neither of us has experienced engine issues. It would be interesting to see actual data either way, but at this point I don't see that happening now that the Hemi is history.

 

[silver billet]

The pulsar makes short work of permanently "disabling" MDS, though it's probably too pricey if that's the only reason you want it.

I refuse to use MDS because I suspect that its harder on the engine while engaged, half the engine starts lugging and I never saw any real increase in MPG anyway.

 

[Boatman22]

Thanks for the replies.

 

[Willwork4truck]

Question for those better educated in drivetrain technology than me.

Gm has the 4 cyl single turbo, Ford the V8 5.0 with mds (like newer hemi) and also ecoboost. Now when my mds equipped hemi is loafing along on a flat or downhill, its in eco mode. As soon as I put even the slightest pressure on the go pedal, or theres a slight grade, its back into v8.

So would it stand to reason that the GM 4 cylinder will act the same and have to boost in order to provide the requested power in the same driving? That would seem to indicate a lot of turbo usage.

The hemi on 4 cyl must be about the same size and power as the GM 4 cyl, yet the hemi rarely can stay in eco mode.

 

[theblet]

Question for those better educated in drivetrain technology than me.

Gm has the 4 cyl single turbo, Ford the V8 5.0 with mds (like newer hemi) and also ecoboost. Now when my mds equipped hemi is loafing along on a flat or downhill, its in eco mode. As soon as I put even the slightest pressure on the go pedal, or theres a slight grade, its back into v8.

So would it stand to reason that the GM 4 cylinder will act the same and have to boost in order to provide the requested power in the same driving? That would seem to indicate a lot of turbo usage.

The hemi on 4 cyl must be about the same size and power as the GM 4 cyl, yet the hemi rarely can stay in eco mode.

Are you referring to the 2.7L? They won't act exactly the same, as cylinder deactivation is completely different than a turbo spooling. Also this engine has less HP, and the two engines would have different hp/tq curves.

I get what you're saying tho, would the delay be similar. I really can't say. But it's apples to oranges

 

[Willwork4truck]

Are you referring to the 2.7L? They won't act exactly the same, as cylinder deactivation is completely different than a turbo spooling. Also this engine has less HP, and the two engines would have different hp/tq curves.

I get what you're saying tho, would the delay be similar. I really can't say. But it's apples to oranges

My neighbor bought the 2.7 4 cyl and 1- it sounds like a sewing machine as he drives off and 2 - he said he's almost always into the boost, so I was wondering.
Seems like the 5.3 V8 for $1600 or so would have been a better choice but that's what they had (2.7 four) on the lot.

 

[Cbty2050]

what's the benefit, peace of mind in my opinion.

https://www.jdpower.com/cars/shopping-guides/cylinder-deactivation-how-it-can-save-fuel#:~:text=Rather%20than%20cut%20off%20fuel,supplied%2C%20causing%20gasoline%20to%20accumulate.

Peace of mind from what?

 

[theblet]

My neighbor bought the 2.7 4 cyl and 1- it sounds like a sewing machine as he drives off and 2 - he said he's almost always into the boost, so I was wondering.
Seems like the 5.3 V8 for $1600 or so would have been a better choice but that's what they had (2.7 four) on the lot.

They probably tuned it to be boosted all the time because it’s such a small engine for a big truck if I had to guess.

 

[silver billet]

My neighbor bought the 2.7 4 cyl and 1- it sounds like a sewing machine as he drives off and 2 - he said he's almost always into the boost, so I was wondering.
Seems like the 5.3 V8 for $1600 or so would have been a better choice but that's what they had (2.7 four) on the lot.

Believe it or not, the 2.7 is doing much better in the half ton than the 5.3 and 6.2 which are plagued with lifter failures, even worse than Ram. The 2.7 doesn't have anything wrong with it per se, no major issues to date.

It feels strong off the line and towing up to 5000 pounds its a very good match.

The 2.7 and 3.0 diesel are the only 2 engines I'd put money on in the GM lineup, and they're both turbos so I'm not likely to do so, but they're both doing better than GM's v8s.