Who does cylinder deactivation well?

None allow you to shut it off. Not in normal driving. There are a few models where there are work arounds, and after market black boxes/ " tunes" that may or may not leave a trace in your ecm that will void your warranty. I know you were saying it in " jest". For example With the Silverado you use the manual mode and move the selector to a certain gear ( it's 5th gear in the 6 speed Silverados) great for city driving and AFM will not engage.
My buddy's F-150 has a switch on the dash that allows him to turn it off. Granted, it has to be done every time the ignition is cycled, but it can still be turned off...
 
Was doing a lot of city driving yesterday in my 5.7L HEMI - 35-45 mph speeds. During light throttle cruise, MDS was engaged - it was not even noticeable, and neither were the transitions. I see zero reason to disable it.
During the summer when running the A/C, the A/C gets warm when the engine shuts off...
 
Was doing a lot of city driving yesterday in my 5.7L HEMI - 35-45 mph speeds. During light throttle cruise, MDS was engaged - it was not even noticeable, and neither were the transitions. I see zero reason to disable it.

Any excessive oil consumption? Did you need to replace the motor mounts? :sneaky:
 
Overkill is right about the low or minimal throttle plate opening. One of the larger losses in gasoline engines is due to engine vacuum at part throttle. Both cylinder deactivation and additional transmission gear ratios address this. With 6 to 10 speed automatic transmissions cylinder deactivation doesn't add much value anymore.

Also, last month I was looking at purchasing a Ram 3500 and noticed that they still are having some issues with cam/lifter failures. Like the GM LS engines the path for splash lubrication from the rod journal is poor, causing problems mainly in police cars that idle most of the day. The other issue with Ram is that the deactivation lifter uses a soft internal lifter spring (intended only for low rpm) for cylinder deactivation that re-activates by having oil pressure activated pins lock this feature out. Rev the engine up quickly, at the pins likely take too long to activate causing the lifter to float, i.e. loose contact with the cam, followed by harsh crashing contact.

It appears that even deactivating the system via a tuner, along with limiting the idle time reduces or possibly eliminates Hemi cam problems. I think the GM LS engines are similar, but my personal GM experiences have been horrible so I'm not sure about that engine.
 
Mi
My buddy's F-150 has a switch on the dash that allows him to turn it off. Granted, it has to be done every time the ignition is cycled, but it can still be turned off...
My F150 has a button for start/ stop . There is also a wiring harness that goes behind that button you can buy aftermarket - or a box that plugs in to the diagnostic port to turn off start/ stop. The downside to the first is the dash has to come apart- but plenty of YouTube videos show how that is done.
 
Cadillac.... V864...
The owner of the company I worked for had one of those back in the 80's. He had a CB radio installed in it. (Back when they were all the rage).

And when he pressed the mike button, the engine would stumble and quit. They finally put some type of electronic filter on it, and it prevented it.
 
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Overkill is right about the low or minimal throttle plate opening. One of the larger losses in gasoline engines is due to engine vacuum at part throttle. Both cylinder deactivation and additional transmission gear ratios address this. With 6 to 10 speed automatic transmissions cylinder deactivation doesn't add much value anymore.

Also, last month I was looking at purchasing a Ram 3500 and noticed that they still are having some issues with cam/lifter failures. Like the GM LS engines the path for splash lubrication from the rod journal is poor, causing problems mainly in police cars that idle most of the day. The other issue with Ram is that the deactivation lifter uses a soft internal lifter spring (intended only for low rpm) for cylinder deactivation that re-activates by having oil pressure activated pins lock this feature out. Rev the engine up quickly, at the pins likely take too long to activate causing the lifter to float, i.e. loose contact with the cam, followed by harsh crashing contact.

It appears that even deactivating the system via a tuner, along with limiting the idle time reduces or possibly eliminates Hemi cam problems. I think the GM LS engines are similar, but my personal GM experiences have been horrible so I'm not sure about that engine.
The HEMI lifters aren't oiled by rod journal splash, there's a big chunk of the block in the way, they are oiled by the pressurized oil provided to the lifter bores which runs down the lifter body and onto the roller/lobe.

It's a materials quality issue with the lifters, not a problem with the engine. It also affects non-MDS lifters and if you do have lifter failure, it's a crap shoot whether it's an MDS one or a non-MDS one that the roller hardening was breached on, and seized up. This is why they've revised the lifters like 7 times. This issue also happens on non-MDS (Hellcat and 6spd cars) engines, though it has been greatly reduced overall apparently, since one of the more recent lifter revisions (both of my vehicles would have the updated lifters).

Basically, if you are one of the (relatively rare) unlucky ones to have improperly hardened rollers/pins, it's only a matter of time before that surface is breached and the needles start to catch, eventually creating enough of a groove that they pile up, the roller stops rolling and away you go. Because cop cars accrue an insane amount of time (hours) on the engines relative to actual miles, it seems to happen quicker on them, but in reality, it just takes more miles for a civilian to accrue the same amount of hours.

I don't believe the # of gears really has any impact, the HEMI has been backed by an 8spd for ages now. Load is load, if you are cruising down the road and using 50HP to maintain your speed, if you turn that engine into a 4-banger, it's going to require more throttle angle to create that 50HP, regardless of whether that's a 4spd or an 8spd, which in turn reduces pumping losses and pushes the engine further up into the efficiency curve, improving gas mileage.
 
The HEMI lifters aren't oiled by rod journal splash, there's a big chunk of the block in the way, they are oiled by the pressurized oil provided to the lifter bores which runs down the lifter body and onto the roller/lobe.
In addition to the lifter bores, the lifters also get oil via the pushrods.

It looks like Ford has problems with their lifters in the 7.3 V8. Unlike FCA/Stelantis, Ford doesn't even bother with taking off the heads and cam at the dealership level. Instead, Ford just sends out a new long block as a replacement (under warranty).

 
In addition to the lifter bores, the lifters also get oil via the pushrods.
The lifters are fed oil down the pushrods on every other rocker, yes, but there doesn't appear to be a concrete answer on whether there's a drain hole in the body on all of them to get that oil to the roller or not. Some I've seen do have that, others don't. But the lifter bodies are all pressure oiled from the big galley that runs across all of them, so there is definitely oil provided to all of them via that method. Roller lifters don't need a massive amount of oil, which is why the LSx engines and HEMI are designed the way they are, while the old pushrod engines from "back in the day" used to drench the cam with oil from the rod journals because you had sliding flat tappets which were far more sensitive.
It looks like Ford has problems with their lifters in the 7.3 V8. Unlike FCA/Stelantis, Ford doesn't even bother with taking off the heads and cam at the dealership level. Instead, Ford just sends out a new long block as a replacement (under warranty).


So, same problem, and no MDS :sneaky:

It's a QC problem. These are probably all coming from China. Federal Mogul made the Ford roller lifters in the 80's and 90's and they were bomb-proof. We need that quality back.
 
But the lifter bodies are all pressure oiled from the big galley that runs across all of them, so there is definitely oil provided to all of them via that method.
What happens when MDS is off?
 
What happens when MDS is off?
That's a separate passage. But it's important to note that the MDS lifters are reverse oiled from the adjacent cylinder because they are an inverted "lifter inside a lifter", so they don't have the same conventional oil path because the MDS pin assembly is in the way, so the inverted lifter is "pumped up" by the adjacent conventional lifter.

This diagram shows that, but it also shows the hole I mentioned where oil could, through the traditional oil band, make its way onto the roller IF that hole is present. However, the pictures I've seen have not been consistent with the presence of this hole, so I'm hesitant to state, definitively, that this is also a way the roller is oiled, while we do know for sure that excess oil coming off the body is definitely going onto the pins and roller.
MDS Lifter breakdown.jpg
 
Rod Knock brings a real puzzle to this discussion.

The Ford 7.3 not only has good rod journal bearing to cam oiling, but it also has piston cooling via oil squirters oiling the cam. This is far better than the original small block Chevy or the hemi that has a cast oil passage blocking much of the area between the rod bearing and the cam. Lifter leakage oiling in my opinion is minimal as the lifter fit is less than half the rod bearing clearance (0.0005 to 0.0010") and the lifters are small diameter allowing for minimal leakage.

Next the lifter roller is plenty large enough to support the 500# valve opening load (open valve spring pressure times 2 for maximum rpm). If the problem was impact loading from floating the lifters at high rpm, then the lifter roller bearings would likely fail. Also, if the lifter roller is too soft then the inside of the lifter roller is likely to fail first due to a higher psi load than the outside of the roller. Maybe the cam itself is too soft?

Has anyone done a Rockwell hardness test of the failed cam and roller lifters? You could probably have it done at a Mechanical Engineering College for free. I know when I went to school, the metalogical class professor would have loved to evaluate this problem.
 
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