4-6-8

[Mathews2004]

How do the new multi displacement engines from Honda (v6) and Dodge (hemi) work? Is it all software, where the computer shuts down fuel and spark under light use conditions? Or is there more to it? Just wondering.

[Treibenschnell]

How do the new multi displacement engines from Honda (v6) and Dodge (hemi) work? Is it all software, where the computer shuts down fuel and spark under light use conditions? Or is there more to it? Just wondering.

The ECU has the injectors shut down and stop spark on those cylinders. So I'd guess it's just all software...

[MadMerv]

They just withdraw feed from some of the gerbils.......

[Mathews2004]

Thanks for that analysis Merv, don't you have to go feed some mini horses?

SO my follow up question is this: If it's all the software controlling this, why don't the manufacturers offer this as a retro fit. Go in, get the ECU flashed, and get 4 more MPG on the SUV or Truck? Why will it take 3 more years to get this on factory vehicles. Why hasn't the aftermarket jumped in? Sort of the opposite of a Super Chip power programmer? Oil company conspiracy? Lazy GM workers? Computer Virus?

[Treibenschnell]

Thanks for that analysis Merv, don't you have to go feed some mini horses?

SO my follow up question is this: If it's all the software controlling this, why don't the manufacturers offer this as a retro fit. Go in, get the ECU flashed, and get 4 more MPG on the SUV or Truck? Why will it take 3 more years to get this on factory vehicles. Why hasn't the aftermarket jumped in? Sort of the opposite of a Super Chip power programmer? Oil company conspiracy? Lazy GM workers? Computer Virus?

Air Bags were available in the mid 70's but not standard for years... who knows why these things happen.

[Dave04]

Thanks for that analysis Merv, don't you have to go feed some mini horses?

SO my follow up question is this: If it's all the software controlling this, why don't the manufacturers offer this as a retro fit. Go in, get the ECU flashed, and get 4 more MPG on the SUV or Truck? Why will it take 3 more years to get this on factory vehicles. Why hasn't the aftermarket jumped in? Sort of the opposite of a Super Chip power programmer? Oil company conspiracy? Lazy GM workers? Computer Virus?

I'm betting that there is some required hardware to support turning off cylinders. This would explain why you can't get it as a simple software flash.

Now, what exactly those differences are... I'll leave up to someone else to post...

[Treibenschnell]

I'm betting that there is some required hardware...

I wouldn't think so... ECUs control spark and injector flow already... so why would anything else be necessary?

[Dave04]

I wouldn't think so... ECUs control spark and injector flow already... so why would anything else be necessary?

OK.... LINK

The system deactivates the valve lifters. This keeps the valves in four cylinders closed, and there is no combustion. In addition to stopping combustion, energy is not lost by pumping air through these cylinders.

Sounds like new hardware to me...

Also, they point out that this system is possible due to...

This system should triumph where the Cadillac 4-6-8 failed because of the speed of modern electronic controls, the sophistication of the algorithms controlling the systems, and the use of electronic throttle control.

Electronic throttle control (aka "accelerator by wire") isn't exactly standard equipment either...

[POS Racing]

4-6-8 isn't new Cadillac first offered the V8-6-4 MOTOR: First car maker to produce a motor that can reduce the number of cylinders being used in accordance with load demands. (1981).

The technology has improved greatly since the infamous Cadillac, but seems as if no one cared until folks started bitching about how much it cost to fill their SUV to go just 350 miles and suddenly we start offering this "new" technology!

BTW. Cadillac also was the first domestic automaker to offer airbags (1975).

[Treibenschnell]

OK.... LINK

Google is a helluva thing!

[MadMerv]

Part of the problem is the mass of carrying those extra pistons when they're not doing any work, especially if the valves are working normally. I remember some early technology that forced both valves open for the entire cycle so there would be no compression on the dead cylinders. Of course, that just adds other problems with the airflow and vacuum in the intake manifold. Also, since so many engines now use four valves per cylinder and overhead cams, that just adds to the complexity. I don't think it will ever work well.

Gotta go feed the horses some gerbils.......

[Dave04]

Gotta go feed the horses some gerbils.......

Be carefull... I hear those horses that eat meat (especially live meat) can be dangerous...

[icepenguin66]

Should be all software like the Corvette ZR1. You put the ignition key in a switch on the centre console and you turn half the motor off (or is it just 2...can't remember)! Vette guys call it the power key! lol

[tailchaser]

Should be all software like the Corvette ZR1. You put the ignition key in a switch on the centre console and you turn half the motor off (or is it just 2...can't remember)! Vette guys call it the power key! lol

If memory serves correctly, the power key turned off the secondary intake runners, making the motor anemic above 4k rpm and effectively cutting 75 horsepower.

[icepenguin66]

Yah, I can't remember have to ask my friend, bastard has 3 of 'em! Didn't GM do the displacement on demand crap on a car or 2 several years ago?