Question about 1999 Grand Marquis

On Wed, 19 Nov 2008 07:49:58 -0500, "C. E. White" wrote:

>
>"Starscream" wrote in message
>
>> Just wondering... The car has a fail-safe cooling system, and
>> according to the manual what it does is alternate between cylinders
>> pumping air into the engine block. Nice idea, but couldn't they
>> adapt that system for everyday use? I mean it's not like it needs
>> all 8 cylinders at cruising speed on the highway anyways. It would
>> have a 4-banger economy on highways, but higher power when needed.
>>
>> Kinda like Chrysler's system. it would help milleage...
>
>The fail safe cooling system cuts off the fuel injectors to cylinders,
>but still allows them to pull in and expel air. They use the air
>pumped through the cylinders to cool the cylinders. This does not
>actually help fuel economy since you are now using the engine as an
>air pump. It may actually hurt fuel economy.

We're talkin' "4.6 Modular" with some bells/whistles for deactivation, etc?

The original 4.6 liquid cooling system is intact?

With some cyl's deactivated, less (not more) cooling is needed?

The whole "fail-safe cooling" thingness is just Garbage-Hype?

There are some folks that will place trust in deactivation systems.

Not po' me!

P

"Take Yo' Hand Out My Pocket (I Ain't Got Nothing What Belongs To You)!"
- Rice Miller, who probably never even _heard_ of GW Bush, Paulson, etc
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C. E. White wrote:
>
> "Starscream" wrote in message
>
>> Just wondering... The car has a fail-safe cooling system, and
>> according to the manual what it does is alternate between cylinders
>> pumping air into the engine block. Nice idea, but couldn't they adapt
>> that system for everyday use? I mean it's not like it needs all 8
>> cylinders at cruising speed on the highway anyways. It would have a
>> 4-banger economy on highways, but higher power when needed.
>>
>> Kinda like Chrysler's system. it would help milleage...
>
> The fail safe cooling system cuts off the fuel injectors to cylinders,
> but still allows them to pull in and expel air. They use the air pumped
> through the cylinders to cool the cylinders. This does not actually help
> fuel economy since you are now using the engine as an air pump. It may
> actually hurt fuel economy. The cylinder deactivation systems used by
> GM, Honda, Chrysler and others avoid pumping losses by deactivating the
> valves for the shut down cylinders as well as the fuel injectors. By
> leaving the valves shut, the engine does not pump air through the
> cylinders (the air in cylinders just acts like a big spring). By doing

makes me wonder...

If it just runs freely, without any restriction (with valves closed it
will use power in order to compress the air), wouldn't it work anyways?

> this they avoid pumping losses (but not frictional losses). However, if
> you aren't pumping air through the cylinders, you cannot cool the
> cylinders which is what Ford does with the fail safe cooling mode. The
> net is, these are two completely different application. BTW, cylinder
> deactivation works a lot better on the EPA dynometer (used to calculate
> the fuel economy ratings) than it does in the real world. Because of
> differences in driving style, the real world experience with cylinder
> deactivation systems varies greatly.Some people report significant
> saving, other no so much.
>

In about any field of application, it always works better on paper than
in real life

> Ed
>
>> Just a thought...
>

Thanks...
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----- Original Message -----
From: "Starscream"
Newsgroups: alt.autos.ford
Sent: Thursday, November 20, 2008 11:48 PM
Subject: Re: Question about 1999 Grand Marquis


> If it just runs freely, without any restriction (with valves closed
> it will use power in order to compress the air), wouldn't it work
> anyways?

If the valves open and close, and you don't inject fuel, you have
created an air pump. It requires power to move the air. If your goal
is to temporarily deactivate the cylinder to pump air through the
cylinder to cool the cylinder, this is justifiable. However, you are
consuming extra power to move the air. For the cylinder deactivation
systems, the valves are deactivated (remain closed) and the fuel
injectors to that cylinder are turned off. While it is true that power
is used to compress the air in the cylinder when the piston is on the
up stroke, this power is mostly returned on the piston's down stroke.
The compressed air in the cylinder acts like a big spring, temporarily
storing energy on the piston's up stroke and returning it on the down
stroke. Cylinder deactivation schemes theoretically work because the
combustion process is more efficient if you throttle the engine less
and run higher pressures and temperatures in the cylinders. By
shutting off some valves and cutting off some cylinder, you make the
other cylinders work harder, but in a more efficient range. If your
goal is cooling a cylinder, leaving the valves closed won't work,
since you won't move any air through the cylinders. The air in the
cylinders, acting like a spring, will just get hotter and hotter, no
help if you need to cool the cylinder.

One of the pet dreams of engine inventors is variable displacement
engines that work by altering the stroke of the engine instead of
throttling the air intake. So far no one has built a successful
production engine that uses this idea but maybe one day.... BMW has
engine systems that do away with a separate throttle plate and vary
the valve opening time / aperture to control the flow of air into the
cylinders. This technique is likely more efficient and should provide
more power for a given displacement, but it requires complicated valve
controls. One day engineers will come up with reasonably priced
electronically controlled valves, then this method will become the
standard. When this comes along, cylinder deactivation will become the
norm for everyone because it will be very easy to do.

Ed
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