Things to do on country drives.

[Diesel Damo]

My latest "entertainer" also improves fuel economy. I call it "see how
many kays you can clock up with the car in neutral and engine doing
nothing but idling". There is one rule - if you drop below 75km/h, you
have to engage a gear again and resume driving as normal (back up
around 100km/h).

On Sunday night, I did my usual 210km/3hr drive to my sister's place in
Blacktown. This game can't be played in the first 20km of this trip as
it's all just struggling on gravel roads. But from the 20km mark to the
100km mark (where I get onto the Great Western Highway), I clocked up
23 "idle" kays, with speeds varying from 80 to 130km/h. One exceptional
single stretch was 4.5km at idle.

I haven't figured out how much fuel I saved yet, but it did add 10
minutes to the trip.

[Stan Marsh]

IMHO, you'd be better coasting in gear. Your engine uses almost no fuel
while coasting in gear, and it's probably safer too.
Then again, engine compression would probably slow you down and you'd be
constantly reaccelerating to 100km
Sounds like a good way to fight fatigue though!

Incidently, my *record* fuel effiecency on my morning commute was about 6.7
l /100km. Golf turbo. :)
Pete

> My latest "entertainer" also improves fuel economy. I call it "see how
> many kays you can clock up with the car in neutral and engine doing
> nothing but idling". There is one rule - if you drop below 75km/h, you
> have to engage a gear again and resume driving as normal (back up
> around 100km/h).

[Ben Thomas]

Diesel Damo wrote:
> My latest "entertainer" also improves fuel economy. I call it "see how
> many kays you can clock up with the car in neutral and engine doing
> nothing but idling". There is one rule - if you drop below 75km/h, you
> have to engage a gear again and resume driving as normal (back up
> around 100km/h).
>
> On Sunday night, I did my usual 210km/3hr drive to my sister's place in
> Blacktown. This game can't be played in the first 20km of this trip as
> it's all just struggling on gravel roads. But from the 20km mark to the
> 100km mark (where I get onto the Great Western Highway), I clocked up
> 23 "idle" kays, with speeds varying from 80 to 130km/h. One exceptional
> single stretch was 4.5km at idle.
>
> I haven't figured out how much fuel I saved yet, but it did add 10
> minutes to the trip.
>

That's how taxi drivers drive, or something similar. They always seemed to jab
the accelerator repeatedly, instead of just leaving their foot in one position
to maintain a particular speed.

--
Ben Thomas - Software Engineer - Melbourne, Australia
2001 manual 2.2l Holden Astra SRi - a real pleasure to drive;
Michelin Preceda - $250 each but last a lot longer than $200 tyres;
Alpine Type S speakers and amp, JVC MP3 CD playing head-unit.

Opinions, conclusions, and other information in this message that do not
relate to the official business of my employer shall be understood as neither
given nor endorsed by it.

[Diesel Damo]

Stan Marsh wrote:

> Your engine uses almost no fuel
> while coasting in gear,

I was under the impression that it uses *no* fuel while coasting in
gear.

> and it's probably safer too.

??? Are you referring to engine (compression) braking in an emergency?
I think the difference would be negligable considering how fast one
could brake from a 5th-gear-compression-zone.

> Then again, engine compression would probably slow you down and you'd
be
> constantly reaccelerating to 100km

Pezactly.

> Sounds like a good way to fight fatigue though!

One of the many ways =)

> Incidently, my *record* fuel effiecency on my morning commute was
about 6.7
> l /100km. Golf turbo. :)

My best is 8.3L/100km. That's country driving too. My NA diesel does
*better* in suburban driving as it hates maintaining 100km/h.

[Forg]

Diesel Damo wrote:
....
>> Your engine uses almost no fuel
>> while coasting in gear,
....
> I was under the impression that it uses
> *no* fuel while coasting in gear.
....

Nah, it still pushes some fuel through; just very little. It's fun to
watch the instantaneous fuel-use numbers on the trip-computer (well, for
a few minutes, then it just becomes more useless & boring information :)).


--
---
Forg! -DUH#6-

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[Scotty]

Driving at a steady rate (on flat ground) is far more economicla than
accelerating to 100 and dropping down to 75 and back up etc as the inertia
required to get the mass back up to speed is far greater than that required
to keep it there.

PS Coasting does use fuel, but only idle fuel which is close to nothing but
still uses as much as sitting at the traffic lights, unless you take into
account the added airflow at 100ks etc but that would be 1/10th of stuff
all.


"Diesel Damo" <Diesel_4WD@yahoo.com.au> wrote in message
news:1105483865.345946.274920@z14g2000cwz.googlegr oups.com...
> Stan Marsh wrote:
>
>> Your engine uses almost no fuel
>> while coasting in gear,
>
> I was under the impression that it uses *no* fuel while coasting in
> gear.
>
>> and it's probably safer too.
>
> ??? Are you referring to engine (compression) braking in an emergency?
> I think the difference would be negligable considering how fast one
> could brake from a 5th-gear-compression-zone.
>
>> Then again, engine compression would probably slow you down and you'd
> be
>> constantly reaccelerating to 100km
>
> Pezactly.
>
>> Sounds like a good way to fight fatigue though!
>
> One of the many ways =)
>
>> Incidently, my *record* fuel effiecency on my morning commute was
> about 6.7
>> l /100km. Golf turbo. :)
>
> My best is 8.3L/100km. That's country driving too. My NA diesel does
> *better* in suburban driving as it hates maintaining 100km/h.
>

[Diesel Damo]

> Driving at a steady rate (on flat ground)

The 100km section I'm talking about ranges between 600m and 1350m above
sea level. There's probably only 2 or 3km of "flat ground" in the whole
drive - hence my initial idea to do this. I didn't play the game for
the last 110km because there is more flat ground than hills. Also, I
won't be playing this game on the way home because there is more
climbing than coasting when going in that direction.

> but still uses as much as sitting at the traffic lights
Except sitting at the traffic lights doesn't take 5km off your trip.

[Toby Ponsenby]

On Tue, 11 Jan 2005 21:10:03 GMT, Ben Thomas wrote:

> That's how taxi drivers drive, or something similar. They always seemed to jab
> the accelerator repeatedly, instead of just leaving their foot in one position
> to maintain a particular speed.

uhhhh.
Taxi drivers who do that are very probably in the same proportion of
blah blah blah... - you just notice it more when you are subjected to
the stupid caper cause they're 'in' the cab.
Also remember that Melbourne cabbies don't (didn't) do any special
driving competence test.
Wait for some clement weather, wind the windows down and have a listen
to the cars around you.
You'll be stunned and amazed, and you'll feel like dumping your entire
savings into oil company shares.
Really:-)
--
Toby
quidquid latine dictum
sit, altum viditur

[Patrick Young]

Diesel Damo wrote:
> My latest "entertainer" also improves fuel economy. I call it "see how
> many kays you can clock up with the car in neutral and engine doing
> nothing but idling". There is one rule - if you drop below 75km/h, you
> have to engage a gear again and resume driving as normal (back up
> around 100km/h).

Diesel engines use an adiabatic compression process, so all you need
is the right gear to keep the engine near idle to negate engine inertia
then you would get to use (some of) the fuel wasted by keeping the
engine idling?

Hmmm, don't think the 'lux tranny is up to that :-)

[Charlie]

that's not saving fuel. modern efi cars won't use any fuel with the
throttle closed, so rolling in gear is much better...

Charlie

[Toby Ponsenby]

On Thu, 13 Jan 2005 17:40:03 +1000, Charlie wrote:

> that's not saving fuel. modern efi cars won't use any fuel with the
> throttle closed, so rolling in gear is much better...
>
> Charlie

Pity.
They should.
--
Toby
quidquid latine dictum
sit, altum viditur

[Charlie]

Toby Ponsenby wrote:

> Pity.
> They should.

why?

Charlie

[Toby Ponsenby]

On Thu, 13 Jan 2005 22:01:04 +1000, Charlie wrote:

> Toby Ponsenby wrote:
>
>> Pity.
>> They should.
>
> why?
>
> Charlie

Before pollution scare regs, injected cars had a small amount of fuel
on over-run.
After pollution scare regs, you are suggesting they don't.

Some hints:
Think oxides of nitrogen.
Think abut who gets to pay for all this anti-pollution shite in the
long run.
You get to pay for the stuff on the car ab initio - and after that you
get to pay to maintain it.
Then you get to pay for less engine life than would otherwise be the
case IF that were to be the result of stuff on the car designed to
meet regulations rather than objectives of longer vehicle life and/or
lesser running expenses. (I can't help it - which would translate to
less pollution in the long term)
And so on and so forth.


--
Toby
quidquid latine dictum
sit, altum viditur

[Diesel Damo]

Charlie wrote:

> that's not saving fuel. modern efi cars won't use any fuel with the
> throttle closed, so rolling in gear is much better...

I understand the concept of what you're saying, but for this car and
for this road, it would have had an overall net fuel saving.

One reason is all the times I coasted up to speeds I normally wouldn't
get to, and then not using any throttle at all to get up the next hill.
Coasting in gear would have provided enough resistance to keep the
speed down, and then making me do the usual NA-diesel-struggle up the
next hill.

[Scotty]

"Diesel Damo" <Diesel_4WD@yahoo.com.au> wrote in message
news:1105653176.339172.209460@c13g2000cwb.googlegr oups.com...
> Charlie wrote:
>
>> that's not saving fuel. modern efi cars won't use any fuel (snip)
say again? So what yoru saying is that my EFI car cuts out as soon as I
Knock it into neutral?

with the
>> throttle closed, so rolling in gear is much better... I do not wish to
>> own such a car that cuts out rolling down hills, makes brakes go hard and
>> steering friggen near impossible.

I think your point is that they still, as carbied cars do , runon Idle fuel
only when coasting.

>
> I understand the concept of what you're saying, but for this car and
> for this road, it would have had an overall net fuel saving.
>
> One reason is all the times I coasted up to speeds I normally wouldn't
> get to, and then not using any throttle at all to get up the next hill.
> Coasting in gear would have provided enough resistance to keep the
> speed down, and then making me do the usual NA-diesel-struggle up the
> next hill.
>

[Diesel Damo]

> So what yoru saying is that my EFI car
> cuts out as soon as I Knock it into neutral?

No, he's saying that a modern EFI car will supply no fuel to the motor
when you're coasting in gear - i.e. the road is driving the wheels.
Coasting in neutral will, as you say, supply the idle amount of fuel.

[athol]

Scotty <noricer@comeagain.com> wrote:

> say again? So what yoru saying is that my EFI car cuts out as soon as I
> Knock it into neutral?

That's not what he meant, even if it could be misread that way.

> I think your point is that they still, as carbied cars do , runon Idle fuel
> only when coasting.

That's what diesels and carbies do, along with _some_ fuel injection
systems.

_Some_ EFI systems actually turn off the fuel when the trans is in
gear, the clutch fully released on a manual and the the throttle
closed _plus_ other criteria are met (manifold vacuum, etc. to let
the computer conclude that the engine is decelerating down a hill.

Simple, really. It's one of the few things that a single point
fuel system (eg LPG mixer) can't emulate. The fact that the VN-on
V6 engines do this is one of the reasons why they are relatively
economical for their size and LPG doesn't achieve as much benefit
as it theoretically should on these engines.

--
Athol
<http://cust.idl.com.au/athol>
Linux Registered User # 254000
I'm a Libran Engineer. I don't argue, I discuss.

[Toby Ponsenby]

On 14 Jan 2005 03:52:09 GMT, athol wrote:

> Scotty <noricer@comeagain.com> wrote:
>
>> say again? So what yoru saying is that my EFI car cuts out as soon as I
>> Knock it into neutral?
>
> That's not what he meant, even if it could be misread that way.
>
>> I think your point is that they still, as carbied cars do , runon Idle fuel
>> only when coasting.
>
> That's what diesels and carbies do, along with _some_ fuel injection
> systems.
>
> _Some_ EFI systems actually turn off the fuel when the trans is in
> gear, the clutch fully released on a manual and the the throttle
> closed _plus_ other criteria are met (manifold vacuum, etc. to let
> the computer conclude that the engine is decelerating down a hill.
>
> Simple, really. It's one of the few things that a single point
> fuel system (eg LPG mixer) can't emulate. The fact that the VN-on
> V6 engines do this is one of the reasons why they are relatively
> economical for their size and LPG doesn't achieve as much benefit
> as it theoretically should on these engines.

Wondering...
If the ECU shuts down the fuel, the same 'signal' could be arranged to
cut the LPG supply either completely or to something less than idle to
avoid flat-spotting when coming off idle. It's still in there telling
the fuel system what to do even though it's turned off otherwise is it
not?

I take it LPG systems do stop the gas on a full trailing throttle
situation?
Not much trying to wet the bores with LPG:-)

--
Toby
quidquid latine dictum
sit, altum viditur

[athol]

Toby Ponsenby <toby@privacy.net> wrote:

> Wondering...
> If the ECU shuts down the fuel, the same 'signal' could be arranged to
> cut the LPG supply either completely or to something less than idle to
> avoid flat-spotting when coming off idle. It's still in there telling
> the fuel system what to do even though it's turned off otherwise is it
> not?

The signal is actually the pulses that actuate the injectors. It
would theoretically be possible to use it but I've not seen anyone
bother.

The problem with single-point fuel delivery, regardless of fuel
type is that there needs to be a blob of fuel/air mixture between
there and the inlet valves at all times - a fuel cut would start
too late and end too late, inevitably causing stalling.

Flat-spotting coming off idle is an indication of incorrect fuel
system adjustment or a POS gas system.

> I take it LPG systems do stop the gas on a full trailing throttle
> situation?

Nope. Not unless you're talking about some of the LPG injection
systems that appear to be common in UK and europe judging by the
comments in uk.rec.cars.fuel.lpg (creation of which was apparently
opposed on the basis that little traffic was expected). For some
reason, these simply haven't reached this ancient continent.

> Not much trying to wet the bores with LPG:-)

Not much washing of oil off the bores, either.

--
Athol
<http://cust.idl.com.au/athol>
Linux Registered User # 254000
I'm a Libran Engineer. I don't argue, I discuss.

[Scotty]

"Diesel Damo" <Diesel_4WD@yahoo.com.au> wrote in message
news:1105671453.316010.239910@z14g2000cwz.googlegr oups.com...
>> So what yoru saying is that my EFI car
>> cuts out as soon as I Knock it into neutral?
>
> No, he's saying that a modern EFI car will supply no fuel to the motor


No fuel equals no motor running!
No motor running equals engine cutout.



> when you're coasting in gear - i.e. the road is driving the wheels.
> Coasting in neutral will, as you say, supply the idle amount of fuel.
>