Good points, Dr. Jefyll.

You are correct that the pumping losses decrease with larger throttle openings, and this fact does reduce some of the negative effects of creating one or more dead cylinders. The manufacturers have tried to reduce the driver's knowledge (and perceived annoyance) of extra vibration and having to press the accelerator to maintain speed by implementing a 'throttle by wire' system that makes the throttle angle adjustment automatically, and by implementing an active motor mount system that softens during these conditions, while still providing the necessary strength when needed to handle the torque of acceleration at full power.

Regarding the excess and unused oxygen being pumped through the system by a simple system's inability to disable the valves for the dead cylinders:

1) The catalyst cannot reduce NOx in the presence of oxygen, and the increased rate of oxidation of HC and CO inside the catalyst can cause dangerous overheating unless carefully monitored and controlled. Upstream air injection systems used in various vehicles are there to provide rapid catalyst warm-up, and are only active during a short warm-up cycle. During that time, stoichiometry (lambda) control is put on hold.

2) The overwhelming majority of lambda feedback systems (especially the kind found in a 1986 Camaro) utilize an O2 sensor in the exhaust stream before the catalyst to perform small trim adjustments. The basic timing and injector pulse-width output maps are based on perceived load, which is calculated from an applicable subset of the MAP, MAF, CTS, RPM, and TPS inputs, and the closed-loop input from the O2 sensor modifies these outputs more for emissions compliance than for drivability. Confusing the lambda system might not have much effect on drivability in and of itself, but it most certainly will have a noticeable (and most likely negative) effect on exhaust emissions.

3) Other emissions-reduction systems such as EGR depend on a non-diluted exhaust sample to remain effective. Neutering these systems will definitely have a negative effect on emissions, and may even potentially place the engine in danger of damage from detonation.

As a licensed CA smog technician, I naturally have a keener focus on emissions than other enthusiasts, but even ignoring that side of the die leaves a lot of things to carefully consider on the other (safety, drivability, economy, etc.) sides.

Perhaps you could try a simple experiment with a minimal manually-operated system, and see how it pans out over a period of a few days, before expending a lot of time and energy engineering an automatic system that may turn out to be impractical or unusable. I'm certainly not trying to rain on everyone's parade, but I felt that it would be neglectful of me to with-hold my $.02.

For the curious, there is a rather well-written article here.

Take care, and best wishes to all,

Mike

EDIT: Dr. Jefyll is a far better word-smith than I am, and privately offered this kind suggestion, which I believe is applicable to the first sentence of the first paragraph above:

"... [I removed Jeff's private comment to me, because it occurred to me that quoting a PM might be considered bad netiquette] ..."

In hindsight, I probably could have chosen "offset" instead of "reduce" in that sentence.

Thanks, Jeff!

When I first found that site after 'Ixquick'ing Cylinder Deactivation, I downloaded and read that manual. The hookup seems very simple, also the product is still being sold which says something. The only danger I've read, in some reviews, is the lack of vacuum available to the brake booster when cylinder deactivation is active, which means the brake pedal will go hard and one will have to press harder on that brake pedal in order to get the same braking action, especially at the higher speeds when cylinder deactivation is most likely to be active. But with a manual control switch to the cylinder deactivation module, I wouldn't think this would be a big problem.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

Yeah, I must say I've developed some admiration for those folks, and some empathy. Just hackers like me, and they've managed to grab hold of an unorthodox idea then hammer and wrestle it into a roadworthy product and bring it to market. That's easier said than done, I betcha.

OK, maybe I'm missing something, but I'd say those reviewers haven't given the matter enough thought. Here's my take on brakes :

• Consider Driver #1, who's got the pedal to the metal. No special reason -- just has a lead foot. Vacuum in the manifold is nearly zero -- a worst-case situation. But if necessary s/he can hop off the gas and stomp on the brake. Takes less than a second. This is something we take for granted.
  
  
• OK, Driver #2 has got the pedal to the metal 'cause half the cylinders are getting no fuel. Vacuum in the manifold is nearly zero, again a worst-case situation. Even if injector deactivation continues s/he can hop off the gas and stomp on the brake, same as Driver #1 -- right?

There is a restriction, but it applies in both cases : you can't expect the brakes to have power assist during times when the accelerator is floored. (It's a restriction of no real consequence.) I admit it's kinda amazing the intake vacuum can recover in less than a second. Come to think of it, there's probably a vacuum reservoir somewhere.

I don't think injector deactivation alters power brakes in any way. With or without it, there'll always be times when the throttle gets cranked open and the vacuum in the manifold disappears.

-- Jeff

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In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

You have a point... Vacuum brake boosters typically hold enough 'trapped' vacuum within the booster (if the one way check valve is functional), that if vacuum was not present the booster would to be able to store 2 or 3 remaining brake applications by foot with diminishing 'power' effect.

With a hydraulic power booster, usually seen in newer trucks, this issue would be non-existent.

I would be tempted to buy one of these cylinder shut-down units and supplement another/cheaper fuel, i.e. hydroxy which is obtained easily from water, low voltage and metal plates which breaks the hydrogen and oxygen molecular bonds to form a non-uniform burnable gas. This fuel would be present on another set of injectors, so the cylinder wouldn't be 'dead'.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

Speaking of the dead cylinders, what exactly happens when the cylinder is deactivated? If the valves aren't jammed open it will act as an engine brake. It would probably make more sense to feed just enough fuel into the cylinder to get it to get it to turn itself over without slowing down the rest of the system. Can anyone tell us what actually happens?

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In theory, there is no difference between theory and practice. In practice, there is. ...Jan van de Snepscheut

Keep in mind that hydrogen is not an energy source, only a storage method. The hydrogen in water has no energy since it is already "burned." To put the energy back into it, you have to "un-burn" it, which is what you're talking about in using electricity to separate it from the oxygen, and it will take more energy to do that than you get out of it by re-burning it, as the process is not 100% efficient.


It might be more efficient to have them jammed shut. You know how when you plug vacuum-cleaner hose with your hand and the motor speed increases because it's not doing any work anymore? The only way to really stop the energy waste though is to disengage the unused pistons and their associated moving parts. The diesel's lack of a throttle to fight sure improves its efficiency though. The energy lost in a throttle valve is force times displacement, and there's plenty of displacement unless it's absolutely totally closed, and there's plenty of force (pressure difference) unless it's totally open. We had an '81 diesel Peugeot station wagon which was deceptively large (even our queen size sofa sleeper went all the way in when we moved), and, loaded up heavy for camping with the back totally full and bikes on the top and back, we'd head into the mountains and still get 35mpg. Unfortunately my wife totaled it in an accident. Now our son has a Ford E-350 diesel work van that weighs over 6,000 pounds empty, with 325hp, and he gets about 18mpg overall.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

It depends. The "engine brake" effect is the result of intake vacuum, and no intake vacuum can be sustained during times when the throttle is fully open. To some that may seem counter-intuitive. But consider all stages of the engine's four-stroke cycle. With the throttle open, on the intake stroke the piston will move down freely. No vacuum is created, as air can enter without restriction. The compression and power strokes simply compress then uncompress the trapped air, like a spring, so there's almost as much energy returned as was consumed. Finally, the piston moves freely on the exhaust stroke, because the air exits without restriction (assuming the manifold & muffler are well designed). Nothing restricts the air flow, therefore the pistons move freely, and the net energy gain/loss for each cycle (four strokes) is virtually zero.

Unfortunately, gasoline engines are fussy about air:fuel ratio, and in order to idle or to run at partial power they must reduce fuel intake and air intake. So gasoline engines include a throttle, whose job is to reduce air flow -- IOW create a restriction! The result is a partial vacuum, created because the engine is no longer free to draw air in. Now we see a braking effect during the intake stroke, because the downward motion of the piston creates a vacuum, which acts to resist the motion. Now you have a form of drag known as pumping losses, aka engine braking.

Engine braking may be helpful when descending a long hill, but otherwise it is pure, 100% bad news. Hills aside, note that engine braking always remains in effect to some degree -- even when cruising -- unless the throttle is fully open. A diesel engine avoids pumping losses by virtue of having no throttle (and hence no vacuum). But a gasoline engine can only minimize pumping losses to the extent that it keeps its throttle open (ie, keeps the vacuum minimal).

Two ways of maximizing the throttle opening are:

• equip the vehicle with a comparatively puny engine. It will run closer to "flat out," and flat out is what's most efficient (open throttle, no vacuum)
• keep your big engine, but withhold fuel from some cylinders. As I explained in my post at the bottom of page 1, the driver will open the throttle further to maintain power.

To be clear, this thread relates to cylinder deactivation via a somewhat dubious approach, intended for retrofit on an existing engine. The fuel injectors are selectively inhibited, which is easy to do, but the valves continue to open and close as usual. (Inhibiting the valve motion is not easy to do, especially as a retrofit!)

Factory installed cylinder deactivation systems do involve inhibiting the valve motion (as well as the fuel injectors). That's a whole different ball game -- but it still revolves around lowering pumping losses. Eliminating those is where the extra fuel economy comes from. (Whew, did I just write all that? Did I screw up anywhere? Hope I'm making sense tonight...!)

-- Jeff
ps- and I see Garth has posted while I was writing this.To eliminate all the energy waste, including mechanical friction, many parts (including pistons) would need to be disengaged. But the factory-designed cylinder-deactivation systems only disengage the valves and injectors, and that's sufficient as a means to minimize pumping losses.Yes, you beat me to that point!
Nicely put!

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In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

Dr. Jefyll is correct. If you just keep the intake and exhaust valves closed, that cylinder acts like a pneumatic spring, and returns most of the energy (minus a small amount of blow-by and friction) on the rebound.

Mike.

Someone once wrote that the best way to transport and recover energy from hydrogen is to attach hydrogen molecules to carbon molecules (in the form of gasoline).

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In theory, there is no difference between theory and practice. In practice, there is. ...Jan van de Snepscheut

It sits in my garage, updated pic here. Much work has been done.
This is the result of the other half of my devoted free time. I dream of putting my knowledge of digital electronics into it and analyzing the return...
It is a GM 1986 TPI system, 2 banks Left & Right, of the engine, firing the fuel injectors. This was before sequential fuel injection. Before the computer knew when to tell each injector when to fire.
Months ago I was looking at the official GM service manual and all the injectors are wired in parallel for the left 4 cylinders and the right 4 cylinders.
It is/was very fast, maybe not so fuel efficient yet. But now it looks even faster.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502