running four cylinders
#22
1st Gear Member
Join Date: Sep 2006
Location: San Angelo,TX fighting polygamy since 4/4/08
Posts: 78
RE: running four cylinders
I have the Gm version in my suburban and the help is minimal. It pretty much only comes on when coasting and on flat roads with no head wind. also, it will not come on at speeds below 20-25 mph.The only way I can tell that it is onis thedash has adisplay mode that tells me v4 or v8 mode. The switch seems instantaneous and there is no vibration like some others have said they have in other vehicles, but suburbans are heavy and that probably helps minimize any vibration.
From what I have read, the GM version closes all valves to the shut down cylinders after combustion. The cylinder then just bounces around off the exhaust gases until needed.
FWIW: I think this type of system would only be good to put on sports/musclecars if the driver had the ability to disable it. While the switch seems seamless in the suburban, I am sure it would be more noticable in a lighter, faster vehicle.
From what I have read, the GM version closes all valves to the shut down cylinders after combustion. The cylinder then just bounces around off the exhaust gases until needed.
FWIW: I think this type of system would only be good to put on sports/musclecars if the driver had the ability to disable it. While the switch seems seamless in the suburban, I am sure it would be more noticable in a lighter, faster vehicle.
#26
RE: running four cylinders
ORIGINAL: Torque07
I know Honda has it on some of their engines, they call it VCM (variable cylinder management). It shuts down 3 of the cylinders while at a cruise.
I know Honda has it on some of their engines, they call it VCM (variable cylinder management). It shuts down 3 of the cylinders while at a cruise.
#27
RE: running four cylinders
Guys - the fail safe mode basically shuts down fuel and spark to alternating cylinders to keep them from producing heat. It doesn't shut down 2, or 4, but it alternates tham each revolution. Your motor becomes an air pump and the air moving through the cylinders keeps the motor cool. Read:
[ul][*]Fail-Safe Cooling[/ul] A fail-safe cooling system lets Mustang be driven under limited power for short distances if engine coolant is lost, eliminating the cost and inconvenience of towing. If the coolant level sensor reads below a critical level, the engine computer module switches the engine to an emergency limp-home mode, in which only half the cylinders get fuel. With only half the cylinders firing, the engine operates at lower power and generates much less heat. The cylinders alternate between even- and odd-firing pistons in this mode. The engine can move the vehicle at moderate speeds (up to about 50 mph).
[ul][*]Fail-Safe Cooling[/ul] A fail-safe cooling system lets Mustang be driven under limited power for short distances if engine coolant is lost, eliminating the cost and inconvenience of towing. If the coolant level sensor reads below a critical level, the engine computer module switches the engine to an emergency limp-home mode, in which only half the cylinders get fuel. With only half the cylinders firing, the engine operates at lower power and generates much less heat. The cylinders alternate between even- and odd-firing pistons in this mode. The engine can move the vehicle at moderate speeds (up to about 50 mph).
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