Variable Displacement V-10?
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Mountain Pass
Joined: Sep 2003
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From: Greenfield,In
Variable Displacement V-10?
This a duplicate post that I did on the "Excursion" Forum - just to be sure to cover the V-10 Experts.
GM,Chrysler,Honda all have Variable Displacement engines now via cutting out 1/2 the cylinders under lite load. They claim 10 - 20 % MPG improvement.
I have begun experimenting with my 2003 V-10 Excursion. I disconnected the 5 Fuel Injectors on the Passenger side. It starts,idles and motors around our subdivision OK. No stange noises or "Check Engine" Light - Water Temp seems normal.
Next I am going to find a way to put switch on that side and try a real life road test. After that an adjustable vacuum switch to make it automatic.
Any thoughts on what harm could be done to the engine??????
GM,Chrysler,Honda all have Variable Displacement engines now via cutting out 1/2 the cylinders under lite load. They claim 10 - 20 % MPG improvement.
I have begun experimenting with my 2003 V-10 Excursion. I disconnected the 5 Fuel Injectors on the Passenger side. It starts,idles and motors around our subdivision OK. No stange noises or "Check Engine" Light - Water Temp seems normal.
Next I am going to find a way to put switch on that side and try a real life road test. After that an adjustable vacuum switch to make it automatic.
Any thoughts on what harm could be done to the engine??????
Last edited by Richard2212; Aug 27, 2005 at 07:37 PM. Reason: Spelling error
Posting Guru
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From: Burnsville, MN
Good luck with this. I don't know what the issues are, say, about the cylinders running dry, but one thing makes me wonder. Obviously the objective is to save gas/ money, but unlike the 5.4's, the V-10's don't have computer-controlled valves yet, so the engine will still be working to compress the air in the unused cylinders. So then the question would be whether in the face of all this extra "friction" and the risk of damage, there would be a satisfactory mileage improvement.
Besides, the V-10's actually already have the ability to run on only 5 cylinders built-in. I think they call it a "limp-home" mode. Supposedly if the computer detects insufficient coolant, it will automatically switch to this mode.
So rather than mechanically adjusting the fuel injectors you would only have to pull the plug on a coolant level sensor, and test your mileage then.
Any way you go though, please keep us posted!!!
Besides, the V-10's actually already have the ability to run on only 5 cylinders built-in. I think they call it a "limp-home" mode. Supposedly if the computer detects insufficient coolant, it will automatically switch to this mode.
So rather than mechanically adjusting the fuel injectors you would only have to pull the plug on a coolant level sensor, and test your mileage then.
Any way you go though, please keep us posted!!!
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You won't realize any benefits.
Just because you are cutting the fuel flow to the cylinders does not mean that the piston in those cylinders is not actually doing work compressing the air that comes in.
You have to shut off the valves too.
Otherwise, that piston to which you stopped fuel flow to is stealing power from the other pistons to compress the air you are still letting in.
So in effect, you are robbing Peter to pay Paul. The other cylinders are doing extra work FOR the cylinder whose fuel you shut off, and thus quite likely are using up more fuel.
Not only that, but you are gumming up your piston rings with oil, and putting unbalanced wear and tear on your crankshaft, since only 5 cylinders are firing normally.
In other words, you are shortening the engine life of your engine, your trucks resale value, and making more mainenance for yourself down the road.
If you want a truck with displacement on demand, wait a year or two, and pretty soon all the manufacturers will have them. It will pretty much be a standard feature soon.
Just because you are cutting the fuel flow to the cylinders does not mean that the piston in those cylinders is not actually doing work compressing the air that comes in.
You have to shut off the valves too.
Otherwise, that piston to which you stopped fuel flow to is stealing power from the other pistons to compress the air you are still letting in.
So in effect, you are robbing Peter to pay Paul. The other cylinders are doing extra work FOR the cylinder whose fuel you shut off, and thus quite likely are using up more fuel.
Not only that, but you are gumming up your piston rings with oil, and putting unbalanced wear and tear on your crankshaft, since only 5 cylinders are firing normally.
In other words, you are shortening the engine life of your engine, your trucks resale value, and making more mainenance for yourself down the road.
If you want a truck with displacement on demand, wait a year or two, and pretty soon all the manufacturers will have them. It will pretty much be a standard feature soon.
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Mountain Pass
Joined: Sep 2003
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From: Greenfield,In
These are good comments and will as with other "POST" lead to a sound technical answer.
My comments: The current GM system intentionally keeps both intake and exhaust valves closed on the cut out cylinders to continuously compress the air in the cylinders. They call it an "air spring" that helps turn over the engine.
I will try the "lime Home" mode. I suspect it just cuts off fuel injectors as I am proposing to do.
Keep the thoughts and discussion going!
My comments: The current GM system intentionally keeps both intake and exhaust valves closed on the cut out cylinders to continuously compress the air in the cylinders. They call it an "air spring" that helps turn over the engine.
I will try the "lime Home" mode. I suspect it just cuts off fuel injectors as I am proposing to do.
Keep the thoughts and discussion going!
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From: Denver, CO
I bet you are also running the five "powered" cylinders rich. You are pumping air not involved with combustion into the exhaust sytem and may be tricking the sensors into thinking you have a lean condition. So you would be dumping extra fuel into the other five cylinders trying to correct the lean condition. If what Im saying is correct you will burn out the cat, and further decrease performance and mileage.
Just sounds like a realy bad idea. I think the "limp" mode is alternating cylinder, right?
Just sounds like a realy bad idea. I think the "limp" mode is alternating cylinder, right?
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The V10 fires side-to-side - it never fires two cylinders on the same side one right after the other.
"limp" mode (sorry guys) fires five cylinders on one side, then alternates to the other side. So for one complete revolution, it fires all the passenger side cylinders, and then the next revolution, fires the driver's side (and vice versa).
I ditto the comment about running rich in the 5 that are firing... the MAF sees a certain amount of air, and tries to run accordingly...
There's far more to this than just disconnecting one side's injectors.
"limp" mode (sorry guys) fires five cylinders on one side, then alternates to the other side. So for one complete revolution, it fires all the passenger side cylinders, and then the next revolution, fires the driver's side (and vice versa).
I ditto the comment about running rich in the 5 that are firing... the MAF sees a certain amount of air, and tries to run accordingly...
There's far more to this than just disconnecting one side's injectors.
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Mountain Pass
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From: Greenfield,In
I am investigating doing what already exists in GM,Chrysler,Honda engines. Your comments will keep driving my investigation. The existing PCM Algorithms control air/fuel mixture, catalytic converter temperature via complex Closed Loop Control techniques.
Each comment - either supportive or not, positive or not - will be factored into my program. I am a retired Ford PowerTrain Engineer, 70 + yr senior,married to a sweet gal and have had my share of those - "that will never work", "why do you want to do that" comments and questions.
Each comment - either supportive or not, positive or not - will be factored into my program. I am a retired Ford PowerTrain Engineer, 70 + yr senior,married to a sweet gal and have had my share of those - "that will never work", "why do you want to do that" comments and questions.
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From: Long Island USA
Originally Posted by Richard2212
I am investigating doing what already exists in GM,Chrysler,Honda engines. Your comments will keep driving my investigation. The existing PCM Algorithms control air/fuel mixture, catalytic converter temperature via complex Closed Loop Control techniques.
Each comment - either supportive or not, positive or not - will be factored into my program. I am a retired Ford PowerTrain Engineer, 70 + yr senior,married to a sweet gal and have had my share of those - "that will never work", "why do you want to do that" comments and questions.
Each comment - either supportive or not, positive or not - will be factored into my program. I am a retired Ford PowerTrain Engineer, 70 + yr senior,married to a sweet gal and have had my share of those - "that will never work", "why do you want to do that" comments and questions.
With that, I'll say this: Wait for Ford to go to variable displacement and buy a new truck
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From: Vancouver Wash USA
Originally Posted by Richard2212
I am investigating doing what already exists in GM,Chrysler,Honda engines. Your comments will keep driving my investigation. The existing PCM Algorithms control air/fuel mixture, catalytic converter temperature via complex Closed Loop Control techniques.
Each comment - either supportive or not, positive or not - will be factored into my program. I am a retired Ford PowerTrain Engineer, 70 + yr senior,married to a sweet gal and have had my share of those - "that will never work", "why do you want to do that" comments and questions.
Each comment - either supportive or not, positive or not - will be factored into my program. I am a retired Ford PowerTrain Engineer, 70 + yr senior,married to a sweet gal and have had my share of those - "that will never work", "why do you want to do that" comments and questions.
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From: Vancouver Wash USA
Originally Posted by krewat
Good attitude...
With that, I'll say this: Wait for Ford to go to variable displacement and buy a new truck
With that, I'll say this: Wait for Ford to go to variable displacement and buy a new truck
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From: Long Island USA
Originally Posted by ken04
Art, Art, guys like you, you know, chick magnets, of course do not have the time to devote to VD OHC engines. But not all of us are so blessed with manly good looks and Arnold-like physiques so we have to sit in dark rooms and figure out how to do the impossible.
All that talk of VD scares me... thank god my truck is a committed one-partner vehicle...