[Sonic03SVT]

I suppose you're right, the friction alone from the moving cylinder shouldnt heat it up too badly. This idea has always intrigued me, and id love to figure out some way to make it work, Id like to know some details on what exactly Dodge is programming the computer to see, how they differentiate between an intended shutdown and a problem, as the ECM is concerned.

[Vettezuki]

Originally Posted by Sonic03SVT

I suppose you're right, the friction alone from the moving cylinder shouldnt heat it up too badly. This idea has always intrigued me, and id love to figure out some way to make it work, Id like to know some details on what exactly Dodge is programming the computer to see, how they differentiate between an intended shutdown and a problem, as the ECM is concerned.

The valves aren't open. You're still compressing air, and that makes it hot. The higher the compression, the higher the temperature. If you have enough residual heat and a little unburnt fuel (from a mis-timed deactivation) you could theoretically get one hell of a detonation.

I'm just guessing, but I suspect there are a lot of good technical reasons it took GM decades to get this technology ready for prime time. And in their reinfined applications on V8s, it *only* gains about 10% total fuel economy.

[enkeivette]

Originally Posted by Vettezuki

The valves aren't open. You're still compressing air, and that makes it hot. The higher the compression, the higher the temperature. If you have enough residual heat and a little unburnt fuel (from a mis-timed deactivation) you could theoretically get one hell of a detonation.

I'm just guessing, but I suspect there are a lot of good technical reasons it took GM decades to get this technology ready for prime time. And in their reinfined applications on V8s, it *only* gains about 10% total fuel economy.

That did cross my mind also, the instant you cut fuel, there may be enough remaining fuel in the chamber for one or two really lean explosions. This is probably why it would be best to cut spark at the same time.

[TimAT]

You'd still have the cylinder(s) that you cut pumping air, and that would add a bunch of load. GM tried that back in the 80's on a Caddy- the original 8-6-4. Problem was they just cut the fuel/spark to the ones they wanted off, and only did it in 4th gear with the convertor locked. Most of them, after a few miles, would shake like a possum passing a peach seed. If you could get the exhaust valve off the seat during the compression stroke you might have a chance.

[big2bird]

Originally Posted by TimAT

You'd still have the cylinder(s) that you cut pumping air, and that would add a bunch of load. GM tried that back in the 80's on a Caddy- the original 8-6-4. Problem was they just cut the fuel/spark to the ones they wanted off, and only did it in 4th gear with the convertor locked. Most of them, after a few miles, would shake like a possum passing a peach seed. If you could get the exhaust valve off the seat during the compression stroke you might have a chance.

Hold the phone. I remember solenoids on the rockers.

[TimAT]

Originally Posted by big2bird

Hold the phone. I remember solenoids on the rockers.

You're right-- CRS kicking in again, but that was what, like 1980? Bottom line was the system worked for a while and then went stoopid. We used to clip the wire going to the 3rd or 4th gear switch on the trans to fix it. Lots easier (and cheaper) that trying to fix the system.

[big2bird]

Originally Posted by TimAT

You're right-- CRS kicking in again, but that was what, like 1980? Bottom line was the system worked for a while and then went stoopid. We used to clip the wire going to the 3rd or 4th gear switch on the trans to fix it. Lots easier (and cheaper) that trying to fix the system.

Yep 81 was the next great failure. 4100HT. I had one. POS.Remember? It had the alum block with iron cylinder sleeves, held in with o-rings? No one would touch it for a rebuild.

[Vettezuki]

Originally Posted by TimAT

You're right-- CRS kicking in again, but that was what, like 1980? Bottom line was the system worked for a while and then went stoopid. We used to clip the wire going to the 3rd or 4th gear switch on the trans to fix it. Lots easier (and cheaper) that trying to fix the system.

I didn't know there were any solenoid activated rockers on any production vehicle. Or am I misunderstanding. Were the solenoids on the 12v system or did they have a separate 40+V system? As you know, automotive companies have been kicking around the idea of a fully electronic valve train to get all the advantages of infinitely programmable valve timing, optimizing power, torque and emissions through all rpms. I guess they just haven't been willing or needed to go that far yet.

Lots of mechanically trick stuff going on with variable valve timing from many of the makers now. Did any of the makers ever consider pneumatic valves like in F1 cars?

[TimAT]

All the solenoids were supposed to do was lift the valves on the selected cylinders off the seat. And in those years it was all 12v.

[big2bird]

Originally Posted by Vettezuki

I didn't know there were any solenoid activated rockers on any production vehicle. Or am I misunderstanding. Were the solenoids on the 12v system or did they have a separate 40+V system? As you know, automotive companies have been kicking around the idea of a fully electronic valve train to get all the advantages of infinitely programmable valve timing, optimizing power, torque and emissions through all rpms. I guess they just haven't been willing or needed to go that far yet.

Lots of mechanically trick stuff going on with variable valve timing from many of the makers now. Did any of the makers ever consider pneumatic valves like in F1 cars?

You have it right. Google Cadillac 8-6-4.
I beleieve the latest tech is solenoids deactivating the hydralic lifters. (You young guys would know).