[V8] Re: cold weather killing gas mileage (AHA!!!)

Tue May 3 10:17:58 EDT 2005

Exactly.

For various reasons the big diesel trucks want to keep the motors at peak
thermal efficiency. They do it by blocking the radiator.
Citroen - being a European company was/is likely to be focused on maximizing
MPG. Remember they have been paying way more for fuel than we have for years.

I remember reading about a developmental motor years ago that was if I remember
right made of ceramic, and the entire engine block was insulated. I think it was
also a 2 cycle, but whatever it was, it got amazing efficiency numbers.
Unfortunately it was not then practical for a production vehicle.

Any gas motor makes power by making heat. (thermal expansion in the combustion
chamber) Any heat that leaks out the tailpipe or out the radiator is wasted
energy.

Dave

Quoting Kneale Brownson <kneale at coslink.net>:

> I remember Citroen cars with little shades that could be operated from
> within the cabin to limit cold air passing over the radiator.  I once
> rigged up a window shade with a cable I could pull from inside to raise it
> up in front of the radiator in my first SAAB.
>
> I used to have a big dump truck that had shutters on the grille to keep air
> off the radiator until the engine warmed.   The big truck had a solenoid of
> some sort that responded to a temperature sensor that let it open the
> shutters gradually.
>
> Maybe we should look into some similar arrangement?
>
> At 04:08 PM 5/2/2005 -0600, dsaad at icehouse.net wrote:
> >In this case, you need to block off part of the radiator core with
> something
> >- I
> >use cardboard. How much you block off depends on how cold it is, and how
> hard
> >you will be driving. At temps well below freezing, the radiator gets to be
> way
> >to efficient - it is designed to keep the motor within temp on a +100F day
> >so it
> >is over capacity most of the time, and way over capacity in the cold winter
> >months. Even with a properly functioning t-stat, if it is 10F degrees
> outside
> >and you are just putting around town, the t-stat will probably be closed
> >most of
> >the time, but when it opens up the motor will get a dose of 10F degree
> water.
> >The t-stat is a slow moving device so it does not just snap off.
> >
> >Long story short is that you want to make it possible for the motor to
> maintain
> >the radiator temp near 97C for maximum MPG. The easiest way to do that is
> to
> >block off some of the radiator to reduce its efficiency. It takes energy
> (gas)
> >to heat up the radiator. It is a backwards way of looking at the cooling
> system
> >but that is how the system works from the motors point of view.
> >
> >Dave
> >
> >
> >
> >Quoting Ed Kellock <ekellock at gmail.com>:
> >
> >
> >Quoting Ed Kellock <ekellock at gmail.com>:
> >
> >> I too run below optimal in the winter unless there's a good long
> >> warmup and then as soon as I start pushing a lot of air through the
> >> nose, it cools off again.
> >> I installed my thermostat and am 99% positive that I put it in
> >> correctly in regard to flow and with the little valve at the top.
> >>
> >> Ed
> >>
> >> On 5/2/05, Ingo Rautenberg <i.rautenberg at waratap.com> wrote:
> >> > You guys have me thinking.  This morning I watched my temp gauge and at
> >> 42°F
> >> > it took (mixed city/hwy) over 20 minutes to get to operating temp.
> Over
> >> > twice as long as I would think.  And thermostat  was replaced less than
> >> 20k
> >> > ago...
> >> >
> >> > Ingo
> >> >
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