My Own Homemade Hybrid Cylinder Dropout System

[jdlmodelt]

Hey, I am attempting to design a circuit to sequentially drop out cylinders on my 99 6.0l silverado. I need to know two things, the firing order and secondly, which pistons oppose each other, i.e. on is in compression stroke and the other is in the exhaust stroke? An exploded view on the engine?

Anybody?

thanks,

James

[redvett]

Good luck on the DOD, You have to remember that you will need to disable the cylinders your shutting off need the intake valve held closed to keep the energy of compression out of the cycle. Your going to have to have PCM software custom made along with the hydraulic lifter system working together.

Its not as easy as you think.

[jdlmodelt]

How is it that I can't just sequentially drop out injectors at some determined frequency w/out adding mechanical features concerning holding certain valves open or closed? If I am cutting down on the amount of fuel that is being delivered at no-load hiway speeds by dropping out certain injectors, how can I not possibly actually increase the mpg. I know I will lose some efficiency, but are you telling me that I will gain nothing?

James

[Steveman]

I am no expert in this but what you are saying sounds way too simple and that means it probably wont work. If a DOD system like this was as simple as what you are trying to do, I bet GM or any other manufacturer would have already tried it. Also if you just drop the amount of fuel being delivered I bet the engine would not work nearly as well, and would probably lose much of its power.

[Steveman]

Also because of the reduced power the engine will have to work harder and so any small mpg gains would be lost. That is why the DOD systems on the gmt-900 trucks are designed to only work with DOD on 5% throttle. Furthermore you would have to design some electronic system to control the injectors and their timing in which they cut out. Like the other guy said, this is no small project. GM spent months, probably a couple of years refining the DOD used in the vehicles today.

[BigJayDogg3]

Also because of the reduced power the engine will have to work harder and so any small mpg gains would be lost. That is why the DOD systems on the gmt-900 trucks are designed to only work with DOD on 5% throttle. Furthermore you would have to design some electronic system to control the injectors and their timing in which they cut out. Like the other guy said, this is no small project. GM spent months, probably a couple of years refining the DOD used in the vehicles today.

 

IIRC they used to have a form of it in an older Cadillac. It was a V8 that could become a 6, and a 4. It didn't work too well. I don't remember when it was, but I want to say it was either in the 80s or the 40s. Those are just guesses though.

[Zembonez]

Also because of the reduced power the engine will have to work harder and so any small mpg gains would be lost. That is why the DOD systems on the gmt-900 trucks are designed to only work with DOD on 5% throttle. Furthermore you would have to design some electronic system to control the injectors and their timing in which they cut out. Like the other guy said, this is no small project. GM spent months, probably a couple of years refining the DOD used in the vehicles today.

 

IIRC they used to have a form of it in an older Cadillac. It was a V8 that could become a 6, and a 4. It didn't work too well. I don't remember when it was, but I want to say it was either in the 80s or the 40s. Those are just guesses though.

 

I believe it was in the 80s. It was called a V8-6-4 engine and it was a horrible flop. Fuel economy did not improve (most reports said it went down) and there were engine meltdowns. Any DOD system has to be able to disable the valvetrain for the deactivated cylinders so that the cylinder can "freewheel" without a compression stroke. It essentially becomes an air pump for the short time it is deactivated. Also the cylinders have to do this randomly so as to keep engine heating uniform or emissions would be affected. It takes a pretty smart computer setup and a ton of data from the sensors to make it work. I don't think a light switch on old cylinder number 6 is gonna help much. (yes I am aware that you are wanting to do something more than that)

[jdlmodelt]

[yes I am aware that you are wanting to do something more than that)

 

You are right, I am indeed wanting to do something more than that. I am using a "Basic Stamp" programmable processor along with some high speed relays. I do plan to experiment with various sequences such that no ONE cylinder gets picked on. I do hold two engineering degrees and 19 years of instrumentation and controls experience ranging from Nuclear facilities to the oil and gas industry to the food manufacturing/packaging industry to gold old fashioned hard 12 hour ranch working days. So, I'm not just some joe with a half-whitted idea. Maybe I am wrong, however, when an engine puts out 300 ponies, it can lose a few going down the hiway under near noload conditions, it shouldn't need ALL of that fuel to get down the road when it doesn't need it.

 

Anyway, as in the beginning of the post. I am looking for an exploded view of the 6.0l vortec engine and the firing order. What I don't need is criticism to try to convince me not to TRY something. (I deeply appreciate all of the insights, don't misunderstand me, I just want to try this to satisfy my own ideas).

thanks,

James

[68haywagon]

To answer your part of your question -

 

Firing order is 1-8-7-2-6-5-4-3

 

Good luck,

 

Mike

[jdlmodelt]

Thanks Mike!

James

[jdlmodelt]

On another note. My mechanic says he observed a local in our area that supposedly installed one of the "Brown's gas" devices on his ford econoline van and went from 20mpg to 88 mpg. I am highly skeptical. However, my mechanic is going to build a device per this guy's specs and test it out for real. So, eventually I'll know more about that but has anyone TRIED? Such that they can give an honest, been there done that answer?

James

[VMax2007]

Any DOD system has to be able to disable the valvetrain for the deactivated cylinders so that the cylinder can "freewheel" without a compression stroke. It essentially becomes an air pump for the short time it is deactivated. Also the cylinders have to do this randomly so as to keep engine heating uniform or emissions would be affected. It takes a pretty smart computer setup and a ton of data from the sensors to make it work. I don't think a light switch on old cylinder number 6 is gonna help much. (yes I am aware that you are wanting to do something more than that)

 

Jim,

 

What do mean by this (in bold)? The current AFM system does NOT randomly shut off cylinders or "rotate" which cyls get deactivated, the SAME 4 cyls are always deactivated. Only 4 cyls have the special lifters.

 

I have heard the old Cadillac DoD system was very similar to the current one, but the main problems were due to the lack of processor speed available at that time. I am not 100% sure about this though, it's just what I have heard.

 

OP: I respect your curiosity and ingenuity as an Engineer. I am also an Engineer and I like to "tinker" too. But I believe what you are trying to do will likely fail, otherwise GM would not have needed special lifters to keep all of the valves on the deactivated cyls closed during 4-mode. It could be a costly experiment IMO.

[Zembonez]

Jim,

 

What do mean by this (in bold)? The current AFM system does NOT randomly shut off cylinders or "rotate" which cyls get deactivated, the SAME 4 cyls are always deactivated. Only 4 cyls have the special lifters.

It is true that a limited number of cylinders are equipped to participate. The control unit does alternate them to maintain equal engine heat displacement. (or at least according to design documentation it does) I do not know exactly how often or how the programming works. I would assume it fires the "disabled" cylinders every somany strokes. I read the technical design documentation on it but that was some time back. That is the full extent of my experience with it. It's a really complex system for what it does. Heaven help us when it decides to start screwing up.

[Zembonez]

On another note. My mechanic says he observed a local in our area that supposedly installed one of the "Brown's gas" devices on his ford econoline van and went from 20mpg to 88 mpg. I am highly skeptical. However, my mechanic is going to build a device per this guy's specs and test it out for real. So, eventually I'll know more about that but has anyone TRIED? Such that they can give an honest, been there done that answer?

James

I'll agree wholeheartedly with the bold part of this post.

 

I also salute you for wanting to tinker with a DOD system. It is a complex system that doesn't offer much return currently. Keep us posted.

[VMax2007]

Jim,

 

What do mean by this (in bold)? The current AFM system does NOT randomly shut off cylinders or "rotate" which cyls get deactivated, the SAME 4 cyls are always deactivated. Only 4 cyls have the special lifters.

It is true that a limited number of cylinders are equipped to participate. The control unit does alternate them to maintain equal engine heat displacement. (or at least according to design documentation it does) I do not know exactly how often or how the programming works. I would assume it fires the "disabled" cylinders every somany strokes. I read the technical design documentation on it but that was some time back. That is the full extent of my experience with it. It's a really complex system for what it does. Heaven help us when it decides to start screwing up.

 

 

It does NOT alternate any deactivated cyls. 4 cyls have the special lifters and those 4 cyls are all deactivated simultanously. It is either 8 or 4.

 

It does however limit the amount of time in 4-mode to 10 consecutive mins max, but I am willing to bet that time limit never gets reached anyway.