V8 to v4 interesting article

I remember seeing articles like this back then. Someone was even trying to market a set of counterweights for the crank so you could remove the pistons and rods from the cylinders that you deactivated.
 
A few years back I bought a 70 Fury that had been converted in a similar fashion. So from a 318 to a 159? It actually got around fairly well although I didn't attempt any highway driving with it. I think it took me a week or so to scrounge up the parts to return it to factory setup.
Mike
 
Id rather use this...

18677d1031382399-electric-turbo-supercharger-esc.jpg
 
It's essentially what Chryslers MDS is. Just shuts down some spark top a few cylinders and allows the lifters to pump down by shutting off the oil pressure to the particular cylinders lifters.
 
67Monaco said:
It's essentially what Chryslers MDS is. Just shuts down some spark top a few cylinders and allows the lifters to pump down by shutting off the oil pressure to the particular cylinders lifters.
Click to expand...

That actually worked real bad in the caddy 4/6/8 and the benz 6/12... because they always shut off the same cylinders and the pistons would pump oil in the chamber... mopar set up worked because it alternates shut downs with burn times through the cylinders... keeps them from loading up.

Its a great idea with electronics to manage it because the power is still on demand. I wouldn't recommend it for something you plan to run in traffic.
 
cantflip said:
That actually worked real bad in the caddy 4/6/8 and the benz 6/12... because they always shut off the same cylinders and the pistons would pump oil in the chamber... mopar set up worked because it alternates shut downs with burn times through the cylinders... keeps them from loading up.
Click to expand...

Mostly right, but not quite complete. Modern Mopar MDS always deactivates the same 4 cylinders (only 4 cylinders even HAVE the hardware to deactivate). But there is a software limit on how long it will run that way, so even if you're cruising for hours at 45 mph on flat land the 4 cylinders will periodically activate for a bit to clean up the deactivated cylinders. At the same time, the electric throttle closes a little so the driver doesn't feel a big bump of power when all 8 come on. GM's "Active Fuel Management" on the LSx engines works pretty much the same way, but they did have more trouble with plugs fouling, high oil consumption, and stuck rings than Chrysler did (some things never change...)

The Caddy V-8-6-4 from the 80s was a failure because it used high-current electrical solenoids to activate and deactivate the valves by engaging or disengaging the rocker arm fulcrums. That much current and power was a big electrical load, and the wiring was in the valve covers, bathed in hot oil. Neither the controller, the solenoids, or the wiring held up very well switching high current under those conditions. It also didn't have an electric throttle that could smooth out the transition from 4 to 6 (which was odd-firing and felt like 2 holes missing). Modern MDS uses oil pressure to do the heavy lifting, and doesn't ever try to operate on 6 cylinders. The MDS Hemi's have a small electrical solenoid mounted under the intake manifold, which diverts oil pressure to or from the special lifters on the cylinders to be deactivated. But its the oil itself that does the work- the solenoid is just moving a little valve.
 
One comment about the original post: I notice that the article leaves the exhaust valves working normally. I guess that solves the problem of oil potentially building up in the "deactivated" cylinders and eventually hydro-locking, but at the same time its going to waste a lot of power pumping hot exhaust gas in and out of the cylinder. So you'll get significantly LESS than half the original power of the engine. If you could close both valves, there would be a lot less pumping loss, but you'd have to figure out how to keep oil from pooling.
 
It wouldn't work well for my many bonzai runs I get to do out here in farmland. I don't drive the car too much so I dont care too much about milage. I was more upset about finding out I had a 26 gallon tank vs a 16 gallon tank!
 
440_Magnum said:
One comment about the original post: I notice that the article leaves the exhaust valves working normally. I guess that solves the problem of oil potentially building up in the "deactivated" cylinders and eventually hydro-locking, but at the same time its going to waste a lot of power pumping hot exhaust gas in and out of the cylinder. So you'll get significantly LESS than half the original power of the engine. If you could close both valves, there would be a lot less pumping loss, but you'd have to figure out how to keep oil from pooling.
Click to expand...
The article removes the exhaust valve and plugs the valve guides with a bolt and nut. The intakes remain in place, but no rocker arms.
 
440_Magnum said:
Mostly right, but not quite complete. Modern Mopar MDS always deactivates the same 4 cylinders (only 4 cylinders even HAVE the hardware to deactivate).

The Caddy V-8-6-4 from the 80s was a failure because it used high-current electrical solenoids to activate and deactivate the valves by engaging or disengaging the rocker arm fulcrums.
Click to expand...

Thank you... I tried to stay a bit vague on the mopar because I wasn't sure how many cylinders were operated, just that they weren't left off long enough to oil foul.

The caddy drivability tech I used to talk to back in the 80s is the one who first told me about the oil fouling issues if the customer drove it too gentile for too long. They had complaints caused by the cylinders loading and misfiring to my understanding... wasn't the guy on that though.

I did personally work on the 12cyl nightmare... we would have them come in with the low part of the intake plenum full of oil sometimes. if the owner never got it to activate the second bank (all six on or off) it would load the cylinders and misfire when they finally did get on it. misfire codes and hesitation complaints were common. This engine also had other problems, which kind of mask the real problem for some folks... you cant leave that cylinder just pumping nothing for too long and then expect it to start firing smoothly. My factory guy didn't like my comparison or comments on that motor... but he wasn't from the motherland so he didn't feel like it was a national pride issue.

The really cool tech for this is variable valve lift. Not some on/off vtec crap... truly variable throughout the range of lift. Those engines don't need throttle valves to control rpm... the valve control is that precise. I have seen some of this in bmws and nissans... but I think everyone has a version of it now.

Thanks again
 
cantflip said:
The really cool tech for this is variable valve lift. Not some on/off vtec crap... truly variable throughout the range of lift. Those engines don't need throttle valves to control rpm... the valve control is that precise. I have seen some of this in bmws and nissans... but I think everyone has a version of it now.

Thanks again
Click to expand...

Not to sound like an FCA "homer" (and it didn't come from the Chrysler side anyway), Fiat's "Multi-Air" system is pretty darn clever. It allows pretty much full variable valve lift and profile, but kinda like MDS it uses oil to do the heavy work rather than big high-current solenoids acting on valves or valve mechanisms. Its not used in a truly continuously-variable sense, as far as I know.

 
Big_John said:
The article removes the exhaust valve and plugs the valve guides with a bolt and nut. The intakes remain in place, but no rocker arms.
Click to expand...

Thanks, I somehow missed that part and only got the fact that they didn't leave the exhaust valve closed.
 
Just got my truck back from the shop, while it was in, I had a 2015 Tahoe that would switch from 4 to 8 cylinders. My two observations were that it was a DOG... Absolutely NO power to take off/accelerate at speed. The other thing I noticed was that for the approx two weeks I had it, it always showed the average gas mileage as 17.7 mpg, never changed. I made several trips north on the interstate, 70 miles one way, and many more beating around town. Never changed from 17.7 mpg. I wonder if GM sourced their mpg software calculator from VW?......:wtf: :bs_flag:
 
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