Driving Without A Thermostat

On Thu, 9 Feb 2005 wrote:

> >Your friend must like stopping at the gas station, because without the
> >thermostat closing your car will get really crappy gas mileage.

> His '94 Ford Full Size truck has no thermostat. He says he gets about 10
> MPG.

Your friend is a moron.

On Thu, 10 Feb 2005, Anthony wrote:

> Actually, IIRC, on newer engines, they route the exhaust gas back in to
> help warm up the engine and fire off the cat faster.

Wrong. What you've got here is a completely garberated concept of EGR,
Exhaust Gas Recirculation. It is NOT to "help warm up the engine", and
it's NOT to "fire off the cat faster". EGR is, in fact, disabled until the
engine is at full operating temperature, and even then, EGR is
intermittent, not constant. Its purpose is to _reduce_ peak combustion
chamber temperatures. This happens because exhaust, being noncombustible,
dilutes the combustible fuel/air charge. The purpose of EGR is to reduce
the formation of NOx ("Oxides of Nitrogen") and control spark knock. And
it's not "new" or "newer"; it's been around since 1972.

DS

On Wed, 9 Feb 2005, John Doe wrote:

> > Highest efficiency is obtained with NO cooling- the so-called
> > adiabatic engine. R&D has not been able to make these work yet, as no
> > lubricants have yet been found to run at the very high temperatures in
> > an adiabatic engine.

> I think it's actually 3 things: NOx, suitable materials (i.e. ceramic) at
> a reasonable cost, and lubricants for high temp that need to be solved
> before they can leave R&D labs.

Smokey Yunick made it work very well.

DS

In article >,
"TeGGer®" > wrote:

> aarcuda69062 > wrote in
> :
>
>
> > EGR usually only operates at light load cruise, on acceleration,
> > the mixture is rich so EGR is not needed to reduce NOx, on decel,
> > fuel is cut off so there isn't enough fire to form NOx.
> > While you're cruising down the Dan Ryan, you really don't need
> > all 3000 cc's under the hood of that Sable, if the EGR opens and
> > displaces the equivalent of 1/3rd (just for a numbers sake) of
> > the engines displacement, don't you in effect now have a more
> > efficient for the job 2000 cc engine doing the light load task
> > asked of it?
>
>
>
> Then how is cruise NOx reduction achieved by cars that don't have EGR and
> can't control how the driver uses the throttle?

Three way or reducing bed in the cat-con, spark control map
including reduction via a knock sensor, variable valve timing,
combustion chamber shape, compression ratio, to name a few.

> It's curious that the automatic transmission version of my Integra had EGR
> while the manual transmission one didn't. Both cars have the same multi-
> port FI.

Do they both use the same part number PCM? I'll bet not.

On Wed, 9 Feb 2005, ed wrote:

> Aren't the exhaust , o2 , and catalytic systems designed to operate at
> certain (hot) temperatures as well? Defintely not optimum. Older cars
> probably dont care too much, but newer ones sure do. (post 1970)

Older cars don't "care", per se, 'cause they don't have electronic brains.
(They do have distributed analogue brains, but that's a different
discussion.). Nevertheless, fuel economy will suffer on an old car with
too low a coolant temperature, due to increased flame quenchout on
(relatively) cold metal within the combustion chamber.

In article >, "TE Cheah" >
wrote:

> | Engine
> | develops more power with cooler intake air. But not with lower coolant
> | temps.
>
> Ridiculous ; why then fit any radiator ?

They wouldn't if it were not for the limitations of the available
build materials.

On Wed, 9 Feb 2005, Professor wrote:

> Strictly speaking... your friend is right.

Strictly speaking...you and his friend are WRONG.

> Computer controlled cars (like yours) may never go off fast-idle.

Er, no. What you meant to say was "Computer controlled
cars (like yours) never enter closed-loop mode".

"Fast idle"...? 1983 was a long time ago, guy.

In article >, "TE Cheah" >
wrote:

> | > I need your opinions on this
> mysterious posters get no info fr me
>
> | The engine becomes more efficient the hotter it gets
> Ridiculous ; both intake air & fuel should be as cool as possible, exactly
> as per 1 article in www.circletrack.com . After I replaced my F20A's
> short & cheap 4into1 manifold & its 2 covers, with a long 4-2-1
> manifold, water temperature dropped, torque @ even low rpm was higher
> , >twice as much @ high rpm.

You're confusing intake charge and fuel temperatures with the
operating temperature of the engine assembly.

You're also confusing power output with efficiency.

On Wed, 9 Feb 2005 wrote:

> A friend told me that a thermostat in a car is not necessary for proper
> engine operation

Wrong. It is *very* necessary to get the engine up to the proper operating
temperature quickly and control it at that point.

> and that the thermostat is mainly there to provide heat for people in
> the car.

Wrong. Even cars without heaters, or with heaters that did not use engine
coolant, had thermostats.

> He said that cooler engines run better, are more powerful, last a lot
> longer, and provides more protection for gaskets.

Wrong and wrong. Your friend is very confused and ignorant. Engines run
best when they are at their design operating temperature. Anything much
hotter or colder seriously degrades engine performance and life. Where the
confusion comes in regards *intake air* temperature, which is best kept as
low as possible for maximum intake charge density and therefore best power
and efficiency. This is NOT the same as engine temperature and is NOT
controlled by the engine thermostat. Furthermore, all vehicles made since
the mid '80s (and a great many made before then) use engine control
computers that look at engine coolant temperature and base fuel
calibration and other parameters upon it. When the computer sees an engine
that is colder than expected, it dumps in extra fuel and slows down the
spark advance. This not only exacts a serious cost in fuel economy and
performance, but the extra fuel washes oil off the cylinder walls, which
is extremely deleterious to engine life. The "gasket" thing is baseless.

> When the thermostats on his cars go bad, he takes them out altogether
> and runs without one. If needed, he even hooks a portable electric
> heater in his vehicles to get heat in the winter. He loves his engines
> to run very cool. When I ride with him, the temperature gauge in his
> cars never even move past 'C'.

He's stupid and ignorant. Humor him if you must, but probably better to
find some friends who are less brainless than that clown.

> What do you think of this? Would it be alright to take the thermostat
> out of my car and drive without one if mine ever goes bad? I drive a '91
> Plymouth Sundance w/ 2.5l engine.

If you do this, your fuel economy and performance will take an enormous
plunge, your heater and defogger will no longer work, you will be rapidly
increasing the wear on your engine and will have to change oil much more
often to keep it clean, and you will set a trouble code 17 (Engine Fails
to Reach Operating Temperature Within Expected Time). Also, you'll never
pass an emissions test.

See anything on this list of "benefits" that looks tasty to you?

DS

"TeGGer®" wrote:

> aarcuda69062 > wrote in
> :
>
> > In article >,
> > "TeGGer®" > wrote:
> >
>
> >>
> >> Then how is cruise NOx reduction achieved by cars that don't have EGR
> >> and can't control how the driver uses the throttle?
> >
> > Three way or reducing bed in the cat-con, spark control map
> > including reduction via a knock sensor, variable valve timing,
> > combustion chamber shape, compression ratio, to name a few.
>
> Can you say why the automaker would install EGR in a car with an automatic
> transmission but not in the manual version of the same car?
>
> --
> TeGGeR®

Good Question: I'll take a shot at it, and then maybe aarcuda and others can
tell me if I'm right.

All auto trans cars I've ever driven cruise at significantly lower rpm than
manuals - often to the point of "almost" lugging the engine. Throttle
response, in my opinion, is always virtually non-existent, but the auto tranny
will usually downshift quickly enough when acceleration is needed that most
auto trans drivers don't care. Anyway, "pulling along" at low rpms *without
egr* and low piston speed tends to generate high peak combustion pressures
favorable to Nox formation. By adding egr, the "peak" pressure is reduced,
while the operation at closer to WOT maintains high enough mean cylinder
pressure to generate the hp needed.

The same car with a manual transmission will cruise at a much higher rpm and
piston speed, thereby generating the needed horsepower with much lower
cylinder pressures. My guess is that in some cases it could be low enough
that egr might not be needed to keep the Nox under control.

Just my guess.

Frank