Accord 04 mileage improved if in-coming air is heated?

My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
measured that miticulously.

If I can somehow warm up likely through passive means not by 12V) the
incoming air before the airfilter, will that improve mileage?

I am talking about temp around 30 F or 0 C only and it is very obvious.

My 99 accord did the same thing. Any input from this NG is
appreciated.

Daniel

On 19 Nov 2005 08:45:01 -0800, wrote:

>My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
>measured that miticulously.
>
>If I can somehow warm up likely through passive means not by 12V) the
>incoming air before the airfilter, will that improve mileage?
>
>I am talking about temp around 30 F or 0 C only and it is very obvious.
>
>My 99 accord did the same thing. Any input from this NG is
>appreciated.
>
>Daniel

The phenomenon of reduced milage in cold weather is well documented,
but you will gain little or nothing by this scheme.

For one thing, most cars already have a mechanism for warming intake
air, although not for this reason. It is to prevent carburetor (now
intake) icing which can occur in humid weather. If warming the air in
winter gave better milage, manufacturers could easily adjust the
system to achieve that. Perhaps to some extent, they do.

Lower fuel economy in cold weather is due to a number of factors.
Much of it is due to colder engines/longer warm-up when the engine is
first started. Warming the intake will have little effect on this.
Another factor, often overlooked, is that the denser air increases
wind resistance. This is a very significant factor on the highway.
(Any pilot will tell you about the huge increase in performance of an
aircraft going from 70F to 0F. They will also tell you about the
increased economy of flying at higher altitude where air density - and
aircraft performance - is reduced.) Obviously, heating the intake air
will do nothing to help you there.

Warmer intake air will be less dense and the FI will reduce the amount
of fuel delivered to compensate. Sounds good except that performance
will be less and you will compensate by opening the throttle further.
That might increase milage due to increased volumetric efficiency
(decreased pumping losses) which means that the engine isn't working
as hard to suck air through the restricted intake. That might offset
some of the above efficiency losses, but only at the expense of a
reduction in maximum power available.

Usually, the mileage goes up, not down when the temperature drops.
That is because there is an increase in volumetric efficiency. I.E.
the air is more dense. I think I would look at other factors. Do you
warm the car up before driving? (shouldn't do that.) Do you drive
through a lot of snow and ice? Are you driving at the same speeds?
Etc. For what it's worth, I drive in those temperatures a lot in the
winter, as well as 100+ in the summer. I don't notice what you are
seeing. 1999 and 2003 Accord V-6's, as well as a 1993 Jeep Grand
Cherokee.

Dick

On 19 Nov 2005 08:45:01 -0800, wrote:

>My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
>measured that miticulously.
>
>If I can somehow warm up likely through passive means not by 12V) the
>incoming air before the airfilter, will that improve mileage?
>
>I am talking about temp around 30 F or 0 C only and it is very obvious.
>
>My 99 accord did the same thing. Any input from this NG is
>appreciated.
>
>Daniel

> wrote in message
oups.com...
> My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
> measured that miticulously.

Probably winter/oxygenated gasoline formulations.

On Sat, 19 Nov 2005 14:16:29 -0500, "MAT"
> wrote:

>
> wrote in message
roups.com...
>> My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
>> measured that miticulously.
>
>Probably winter/oxygenated gasoline formulations.
>

Good point. I forgot about that one.

"Dick" <LeadWinger> wrote
> Usually, the mileage goes up, not down when the
temperature drops.
> That is because there is an increase in volumetric
efficiency. I.E.
> the air is more dense.

You're thinking of, for example, certain diesel designs that
cool the intake air so as to pack more in for each cycle.

What you say above is not so for automotive engines. Several
people have already identified several of the reasons why
fuel efficiency in automotive designs is lower at lower
ambient temperatures. For my part, I'm partial to the fact
that the engine has to combust more fuel to achieve the same
temperatures everywhere, yada, all per the car's engine
control computer directions. But then too is the fact that
the oil is denser, and this has an effect on efficiency.
Another poster talked about wind resistance being worse,
since the ambient air is denser, and I'm inclined to buy
that, also. Wind resistance has the greatest effect on fuel
efficiency.

Dick wrote:
> On Sat, 19 Nov 2005 14:16:29 -0500, "MAT"
> > wrote:
>
> >
> > wrote in message
> roups.com...
> >> My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
> >> measured that miticulously.
> >
> >Probably winter/oxygenated gasoline formulations.
>
> Good point. I forgot about that one.

Also, cold fuel is denser and harder to vaporize.

David

Gordon McGrew wrote:
> On 19 Nov 2005 08:45:01 -0800, wrote:
>
>
>>My accord 04 4 cyl mileage drops by 10-15% in winter time and I have
>>measured that miticulously.
>>
>>If I can somehow warm up likely through passive means not by 12V) the
>>incoming air before the airfilter, will that improve mileage?
>>
>>I am talking about temp around 30 F or 0 C only and it is very obvious.
>>
>>My 99 accord did the same thing. Any input from this NG is
>>appreciated.
>>
>>Daniel
>
>
> The phenomenon of reduced milage in cold weather is well documented,
> but you will gain little or nothing by this scheme.
>
> For one thing, most cars already have a mechanism for warming intake
> air, although not for this reason. It is to prevent carburetor (now
> intake) icing which can occur in humid weather. If warming the air in
> winter gave better milage, manufacturers could easily adjust the
> system to achieve that. Perhaps to some extent, they do.
>
> Lower fuel economy in cold weather is due to a number of factors.
> Much of it is due to colder engines/longer warm-up when the engine is
> first started.

ok.

> Warming the intake will have little effect on this.

not true. increasing intake temp at this time /can/ decrease warmup time.

> Another factor, often overlooked, is that the denser air increases
> wind resistance.

true.

> This is a very significant factor on the highway.
> (Any pilot will tell you about the huge increase in performance of an
> aircraft going from 70F to 0F.

doesn't this contradict your air density statement?

> They will also tell you about the
> increased economy of flying at higher altitude where air density - and
> aircraft performance - is reduced.) Obviously, heating the intake air
> will do nothing to help you there.

dude, you're all over the shop. density increases as temperature drops.
density decreases as you increase altitude. that's not the same thing.
by your rationale, air would be denser as you go higher because of the
decreased temperature. economic flying at higher altitude is because
the skin of the plane has less friction, not because the engine is
finding it easier to suck in air. in fact, the opposite is true.
that's where turbos & super charges come from - the need to increase air
volume in aero engines at high altitude because air density is too low
to produce needed power.

>
> Warmer intake air will be less dense and the FI will reduce the amount
> of fuel delivered to compensate. Sounds good except that performance
> will be less and you will compensate by opening the throttle further.

ok

> That might increase milage due to increased volumetric efficiency
> (decreased pumping losses) which means that the engine isn't working
> as hard to suck air through the restricted intake. That might offset
> some of the above efficiency losses, but only at the expense of a
> reduction in maximum power available.

eh? increased volumetric efficiency as manifold pressure decreases? wow.

bottom line, no, there are two factors against high air temps for cars.

1. higher temp is lower density. lower density = less oxygen to burn gas.

2. higher temp is higher viscosity. higher viscosity makes it harder to
ges the air into the cylinder. that's why turbos have intercoolers.
http://www.ce.utexas.edu/prof/kinnas...ynviscgif.html

and regarding lower mileage in the winter, one of the biggest factors is
a change in gas formulation. "winter" grades of gas have lower
calorific content.

"jim beam" > wrote
> and regarding lower mileage in the winter, one of the
biggest factors is
> a change in gas formulation. "winter" grades of gas have
lower
> calorific content.

You have referred to this often. I finally googled. Does
this web site and its accompanying sites discuss what you
mean?

http://www.epa.gov/oms/rfg/whereyoulive.htm

If so, the part of the country that uses this lower calorie
fuel is extraordinarily geographically small. It's certainly
not nationwide.

Aside: Your refusal to snip posts to which you are replying
and so repeat ad nauseam is rude. Very.

Elle wrote:
> "jim beam" > wrote
>
>>and regarding lower mileage in the winter, one of the
>
> biggest factors is
>
>>a change in gas formulation. "winter" grades of gas have
>
> lower
>
>>calorific content.
>
>
> You have referred to this often. I finally googled. Does
> this web site and its accompanying sites discuss what you
> mean?
>
> http://www.epa.gov/oms/rfg/whereyoulive.htm
>
> If so, the part of the country that uses this lower calorie
> fuel is extraordinarily geographically small. It's certainly
> not nationwide.

it's nationwide and seasonal. "The heating value of winter gasoline is
about 1.5 percent lower than summer gasoline because winter gasoline
contains more volatile, less dense hydrocarbons."
http://www.chevron.com/products/prod.../pg4.asp#power
i've cited this before.

>
> Aside: Your refusal to snip posts to which you are replying
> and so repeat ad nauseam is rude. Very.

go forth and multiply. a logical argument requires retention of
relevant points. it's pathetic how frequently and how telling is the
snippage of detail from those seeking to avoid a point that contradicts
them. i'm surprised you're not top posting in protest.