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OT: Petrol consumption
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Meindert Sprang
electronics forum Guru Wannabe


Joined: 15 Jul 2005
Posts: 150

PostPosted: Wed Jul 19, 2006 10:33 am    Post subject: Re: OT: Petrol consumption Reply with quote

"glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
news:xfydnRK5o8wNaiDZnZ2dnUVZ_sKdnZ2d@comcast.com...
Quote:
Eeyore wrote:

(snip)

A/C's another matter - and that *does* take a load of power
from the engine via the compressor.

Last I heard, above about 40mi/h the AC takes less power than
the increased drag of having the windows open.

Been watching Mythbusters?

Quote:
A secondary effect is the change in engine temperature
with the AC heat from the condenser core going into the radiator.

That would be a separate radiator in my car IIRC.

Meindert
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pomerado@hotmail.com
electronics forum beginner


Joined: 19 Jun 2006
Posts: 41

PostPosted: Wed Jul 19, 2006 10:36 am    Post subject: Re: OT: Petrol consumption Reply with quote

glen herrmannsfeldt wrote:
Quote:
Eeyore wrote:

(snip)

A/C's another matter - and that *does* take a load of power
from the engine via the compressor.

Last I heard, above about 40mi/h the AC takes less power than
the increased drag of having the windows open.

A secondary effect is the change in engine temperature
with the AC heat from the condenser core going into the radiator.

-- glen

Last night I drove my wife to the LA airport (about 2 hours). We took
her new car, which as an mpg readout in the instrument panel. On the
way up, with the AC on, we were running about 26-28 mpg. Returning
after dark, with the AC off, we wer getting 31-33 mpg. We were going
65-75 mph both ways, depending on traffic, and hills were trivial
either way (Route 91 from Corona to LAX and return).
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Roger Hamlett
electronics forum Guru


Joined: 28 Apr 2005
Posts: 302

PostPosted: Wed Jul 19, 2006 11:03 am    Post subject: Re: OT: Petrol consumption Reply with quote

"Richard Henry" <pomerado@hotmail.com> wrote in message
news:1153305384.321533.42070@s13g2000cwa.googlegroups.com...
Quote:

glen herrmannsfeldt wrote:
Eeyore wrote:

(snip)

A/C's another matter - and that *does* take a load of power
from the engine via the compressor.

Last I heard, above about 40mi/h the AC takes less power than
the increased drag of having the windows open.

A secondary effect is the change in engine temperature
with the AC heat from the condenser core going into the radiator.

-- glen

Last night I drove my wife to the LA airport (about 2 hours). We took
her new car, which as an mpg readout in the instrument panel. On the
way up, with the AC on, we were running about 26-28 mpg. Returning
after dark, with the AC off, we wer getting 31-33 mpg. We were going
65-75 mph both ways, depending on traffic, and hills were trivial
either way (Route 91 from Corona to LAX and return).
This is quite common. As well as the change from the A/C, the engine runs

more efficiently, when the OAT is lower (within certain limits). In the
UK, on a run I used to do very often, a cool, slightly damp morning,
returned the 'best' economy.

Best Wishes
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Eeyore
electronics forum Guru


Joined: 22 Jun 2006
Posts: 642

PostPosted: Wed Jul 19, 2006 11:14 am    Post subject: Re: OT: Petrol consumption Reply with quote

Roger Hamlett wrote:

Quote:
"Richard Henry" <pomerado@hotmail.com> wrote in message
news:1153305384.321533.42070@s13g2000cwa.googlegroups.com...

glen herrmannsfeldt wrote:
Eeyore wrote:

(snip)

A/C's another matter - and that *does* take a load of power
from the engine via the compressor.

Last I heard, above about 40mi/h the AC takes less power than
the increased drag of having the windows open.

A secondary effect is the change in engine temperature
with the AC heat from the condenser core going into the radiator.

-- glen

Last night I drove my wife to the LA airport (about 2 hours). We took
her new car, which as an mpg readout in the instrument panel. On the
way up, with the AC on, we were running about 26-28 mpg. Returning
after dark, with the AC off, we wer getting 31-33 mpg. We were going
65-75 mph both ways, depending on traffic, and hills were trivial
either way (Route 91 from Corona to LAX and return).
This is quite common. As well as the change from the A/C, the engine runs
more efficiently, when the OAT is lower (within certain limits). In the
UK, on a run I used to do very often, a cool, slightly damp morning,
returned the 'best' economy.

Have you ever noticed that the engine is distinctly more sprightly under some
weather conditions tooo ?

Graham
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Andreas Huennebeck
electronics forum beginner


Joined: 19 Jul 2006
Posts: 1

PostPosted: Wed Jul 19, 2006 12:14 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Mad Prof wrote:

Quote:
Anybody know if more petrol is consumed when the car headlights are on? If
so how significant is it.

As far as I remember the ADAC (German automobile club) calculated the
additional consumption as 0.1 liter / 100 km. They did this when some
german politicians wanted to enforce car drivers to drive with lights
switched on always, even during the day, like they do in scandinavia
since many years.

So for a single driver this is below the noise floor (you can spare up to
30% fuel consumption just by using a good driving style[1] - here in Germany
you can learn this in special driving lessons), but for all drivers in the country
it accumulates to astounding values.

My current milage: 5.2 liters / 100 km (95 octane) = 45.2 miles/gallon on a Honda Jazz.

bye
Andreas
--
Andreas Hünnebeck | email: acmh@gmx.de
----- privat ---- | www : http://www.huennebeck-online.de
Fax/Anrufbeantworter: 0721/151-284301
GPG-Key: http://www.huennebeck-online.de/public_keys/andreas.asc
PGP-Key: http://www.huennebeck-online.de/public_keys/pgp_andreas.asc
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Johnny Baker
electronics forum beginner


Joined: 19 Jul 2006
Posts: 1

PostPosted: Wed Jul 19, 2006 12:48 pm    Post subject: Re: Petrol consumption Reply with quote

OK, you've got 2 lights of 55 W each, so 110 W is consumed by lights -
that's about 0.14 horse power!


"Mad Prof" <mad@uni.com> wrote in message
news:44bd989a$0$19689$88260bb3@free.teranews.com...
Quote:
Anybody know if more petrol is consumed when the car headlights are on? If
so how significant is it.
I assume there must be more fuel needed since the batter is only used on
start-up - the generator being the main source of electrical power and it
is driven by the engine.


M.P



--
Posted via a free Usenet account from http://www.teranews.com
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Roger Hamlett
electronics forum Guru


Joined: 28 Apr 2005
Posts: 302

PostPosted: Wed Jul 19, 2006 1:08 pm    Post subject: Re: OT: Petrol consumption Reply with quote

"Eeyore" <rabbitsfriendsandrelations@REMOVETHIS.hotmail.com> wrote in
message news:44BE1407.1C775B6C@REMOVETHIS.hotmail.com...
Quote:


Roger Hamlett wrote:

"Richard Henry" <pomerado@hotmail.com> wrote in message
news:1153305384.321533.42070@s13g2000cwa.googlegroups.com...

glen herrmannsfeldt wrote:
Eeyore wrote:

(snip)

A/C's another matter - and that *does* take a load of power
from the engine via the compressor.

Last I heard, above about 40mi/h the AC takes less power than
the increased drag of having the windows open.

A secondary effect is the change in engine temperature
with the AC heat from the condenser core going into the radiator.

-- glen

Last night I drove my wife to the LA airport (about 2 hours). We
took
her new car, which as an mpg readout in the instrument panel. On the
way up, with the AC on, we were running about 26-28 mpg. Returning
after dark, with the AC off, we wer getting 31-33 mpg. We were going
65-75 mph both ways, depending on traffic, and hills were trivial
either way (Route 91 from Corona to LAX and return).
This is quite common. As well as the change from the A/C, the engine
runs
more efficiently, when the OAT is lower (within certain limits). In the
UK, on a run I used to do very often, a cool, slightly damp morning,
returned the 'best' economy.

Have you ever noticed that the engine is distinctly more sprightly under
some
weather conditions tooo ?

Graham
Yes.

I think it has become slightly less noticeable on modern cars and with
modern lubricants and fuel injection, but on older models, there were days
when the engine just wanted to 'sing', and others when it felt like half
the cylinders were missing!. I'd put 90% of it down to the mixture control
on these engines though. Temperature is the big beast in regard to overall
engine 'output'. On light aircraft, you use a slightly 'safe' factor of
10% loss in take-off performance for every 10C change in air
temperature...

Best Wishes
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Mark
electronics forum Guru


Joined: 03 May 2005
Posts: 329

PostPosted: Wed Jul 19, 2006 2:04 pm    Post subject: Re: Petrol consumption Reply with quote

Quote:

Now consider the cost in energy to build a car multiplied by the
increased probability of totaling the car in an accident when
the lights are off.

-- glen

this is the correct answer, the fuel cost to run the headlights is MUCH
lower compared to the "probability cost" of reducing the chances of
having an accident.

Mark
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Jerry Avins
electronics forum Guru Wannabe


Joined: 29 Apr 2005
Posts: 127

PostPosted: Wed Jul 19, 2006 4:59 pm    Post subject: Re: OT: Petrol consumption Reply with quote

glen herrmannsfeldt wrote:
Quote:
Jerry Avins wrote:

(snip)

Running the headlights with the engine off uses even more petrol,
since the alternator eventually supplies the energy, but at reduced
overall efficiency. The headlights consume energy; where do you
suppose the energy comes from?

You could use a similar argument to say that it should consume more
fuel with the heater on high than low, as the heat energy has to come
from somewhere, but I believe that one isn't true.

Sure it's true. The heater fan runs faster. (But in some weather in some
cars with electric cooling fans, their duty cycle might go down,
offsetting the heater fan's extra draw.)

Quote:
I am not yet convinced that headlight use is more than the measurement
error in fuel consumption, though.

The bulbs I remember were about 60 watts apiece. I doubt if modern bulbs
run less. Tail-light bulbs IIRC are about 10 watts. The alternator
efficiency is about 90%, and the battery discharge-recharge cycle about
80%. I guess that the lighting system consumes about 1/5 hp.

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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Jerry Avins
electronics forum Guru Wannabe


Joined: 29 Apr 2005
Posts: 127

PostPosted: Wed Jul 19, 2006 5:06 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Eeyore wrote:
Quote:

bbhack@gmail.com wrote:

...

Quote:
Although thinking of power plants in terms of kW is really
weird.

Not for those in the utility business!

Quote:
It's almost the same as hp.

More like 3/4. (Actually, .746, I remember it as half of 1492, a
significant date in history.)

Quote:
And forget about km/l. That's just too foreign.

It's the wrong way up ! Who wants to know the inverse of mileage ?

Drivers of Sherman tanks? :-)

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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Jerry Avins
electronics forum Guru Wannabe


Joined: 29 Apr 2005
Posts: 127

PostPosted: Wed Jul 19, 2006 5:12 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Meindert Sprang wrote:
Quote:
"glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
news:xfydnRK5o8wNaiDZnZ2dnUVZ_sKdnZ2d@comcast.com...

...

Quote:
A secondary effect is the change in engine temperature
with the AC heat from the condenser core going into the radiator.

That would be a separate radiator in my car IIRC.

In all cars. Usually, though, the AC condenser is in front of the engine
radiator, so th radiator's cooling air is warmer with AC on.

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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Jerry Avins
electronics forum Guru Wannabe


Joined: 29 Apr 2005
Posts: 127

PostPosted: Wed Jul 19, 2006 5:20 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Roger Hamlett wrote:
Quote:
"Eeyore" <rabbitsfriendsandrelations@REMOVETHIS.hotmail.com> wrote in
message news:44BE1407.1C775B6C@REMOVETHIS.hotmail.com...

...

Quote:
Have you ever noticed that the engine is distinctly more sprightly under
some
weather conditions tooo ?

Graham
Yes.
I think it has become slightly less noticeable on modern cars and with
modern lubricants and fuel injection, but on older models, there were days
when the engine just wanted to 'sing', and others when it felt like half
the cylinders were missing!. I'd put 90% of it down to the mixture control
on these engines though. Temperature is the big beast in regard to overall
engine 'output'. On light aircraft, you use a slightly 'safe' factor of
10% loss in take-off performance for every 10C change in air
temperature...

I kept the ignition timing on the edge of too advanced in my '53 Ford
F-head. I could just make it knock a little between 35 and 45 mph when
floored in third gear. That is, except on humid days. Fog was just like
retarding the timing. The engine ran smoother, but with less oomph.

Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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pomerado@hotmail.com
electronics forum beginner


Joined: 19 Jun 2006
Posts: 41

PostPosted: Wed Jul 19, 2006 5:26 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Jerry Avins wrote:

Quote:
I kept the ignition timing on the edge of too advanced in my '53 Ford
F-head. I could just make it knock a little between 35 and 45 mph when
floored in third gear. That is, except on humid days. Fog was just like
retarding the timing. The engine ran smoother, but with less oomph.

Some old military aircraft engines injected water to make the engines
run better.
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Jerry Avins
electronics forum Guru Wannabe


Joined: 29 Apr 2005
Posts: 127

PostPosted: Wed Jul 19, 2006 6:35 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Richard Henry wrote:
Quote:
Jerry Avins wrote:

I kept the ignition timing on the edge of too advanced in my '53 Ford
F-head. I could just make it knock a little between 35 and 45 mph when
floored in third gear. That is, except on humid days. Fog was just like
retarding the timing. The engine ran smoother, but with less oomph.

Some old military aircraft engines injected water to make the engines
run better.

The practice started with drag racers before WWII. As one story goes, an
aircraft mechanic in the Pacific theater who gad been a drag racer in
civilian life equipped his pilot's P-47 Thunderbolt with a make-shift
water-injection system to better defend against the more nimble Japanese
Zeros. (The Thunderbolt was a magnificent fighter, as heavy and with as
much horsepower as a DC-3 cargo plane. It was heavily armed and armored,
and fast on the level. Because of its weight, it was relatively slow to
turn and climb. The Zero had no armor at all, not even room for a
parachute. They would climb rapidly and dive down on the Thunderbolts,
shooting through the canopy if the pilot didn't roll.

The mechanic's word to his pilot was supposedly something like "If you
get into trouble, pull this handle. Horsepower should go from 2300 to
3000 if the engine doesn't blow up." Later tests indicated something
more like 2800 than 3000, but it was enough. When a Zero tried to
outclimb him, the pilot headed straight up and, hanging on his prop,
raked the Zero's belly.

All was not immediately well, however. The pilot included details of the
maneuver in his debriefing, and the base commander court martialed both
him and his mechanic for unauthorized tampering with Government
property. The court martial order was sent for approval to the division
general, who quashed it and ordered the modification made to all the
Thunderbolts in his command, under the tutelage of the mechanic.

Can anyone confirm the details? I heard the story from a returning
veteran, with no corroboration.

I was once shot at (sort of) by a P-47, but that's another story.
http://www.wpafb.af.mil/museum/air_power/ap7.htm

jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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Richard Owlett
electronics forum beginner


Joined: 25 Apr 2005
Posts: 19

PostPosted: Wed Jul 19, 2006 6:48 pm    Post subject: Re: OT: Petrol consumption Reply with quote

Jerry Avins wrote:

Quote:
Richard Henry wrote:

Jerry Avins wrote:

I kept the ignition timing on the edge of too advanced in my '53 Ford
F-head. I could just make it knock a little between 35 and 45 mph when
floored in third gear. That is, except on humid days. Fog was just like
retarding the timing. The engine ran smoother, but with less oomph.


Some old military aircraft engines injected water to make the engines
run better.


The practice started with drag racers before WWII. As one story goes, an
aircraft mechanic in the Pacific theater who gad been a drag racer in
civilian life equipped his pilot's P-47 Thunderbolt with a make-shift
water-injection system to better defend against the more nimble Japanese
Zeros. (The Thunderbolt was a magnificent fighter, as heavy and with as
much horsepower as a DC-3 cargo plane. It was heavily armed and armored,
and fast on the level. Because of its weight, it was relatively slow to
turn and climb. The Zero had no armor at all, not even room for a
parachute. They would climb rapidly and dive down on the Thunderbolts,
shooting through the canopy if the pilot didn't roll.

The mechanic's word to his pilot was supposedly something like "If you
get into trouble, pull this handle. Horsepower should go from 2300 to
3000 if the engine doesn't blow up." Later tests indicated something
more like 2800 than 3000, but it was enough. When a Zero tried to
outclimb him, the pilot headed straight up and, hanging on his prop,
raked the Zero's belly.

All was not immediately well, however. The pilot included details of the
maneuver in his debriefing, and the base commander court martialed both
him and his mechanic for unauthorized tampering with Government
property. The court martial order was sent for approval to the division
general, who quashed it and ordered the modification made to all the
Thunderbolts in his command, under the tutelage of the mechanic.

Can anyone confirm the details?

Not the details.
BUT I've read similar about the war in Europe.

For perspective my parents were married 12/06/41

when they retrieved my mother's affects after the honeymoon

My grandfather is reported saying
"SEE WHAT YOU STARTED"

lol


I heard the story from a returning
Quote:
veteran, with no corroboration.

I was once shot at (sort of) by a P-47, but that's another story.
http://www.wpafb.af.mil/museum/air_power/ap7.htm

jerry
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