Stupid "free energy" idea

> wrote in message
...
>> How much fuel does an engine use when you are going downhill with your
>> foot
>> off the throttle, using engine braking? I'd expect it to be about as much
>> as
>> with the engine idling. Just because the engine is running faster and
>> there's a greater throughput of air due to the more frequent induction
>> strokes, why should that cause more fuel to be used, assuming you have
>> fuel
>> injection rather than a carburettor?
>
> It causes more fuel to be used because the engine compression retards
> your increase in speed, decreasing your roll out and requiring you to
> come onto the gas sooner.
>
> If you let gravity accelerate you in neutral you WILL find that many
> hills will do work for you that require significant throttle just to
> overcome the engine compression at the RPMs that your engine spins at
> at this speed.
>
> ****...just coast on a flat. See how far you roll, losing little
> speed. Then, try the same thing by lifting your foot off the
> accelerator.
>
>> Is the fuel consumption the same if you coast downhill with the engine on
>> but the clutch pressed and/or the transmission in neutral?
>
> the fuel consumption is the same WHILE you are going downhill,
> HOWEVER, in SOME cases, overcoming engine compression requires
> ADDITIONAL fuel.


Ah, I see what you're saying: you're prepared to accelerate down the hill to
a speed above what you were doing on the flat, and let that carry you part
of the way up the hill on the far side. Yes, I agree: coating in neutral
will involve less braking so you'll go further up the other side before you
have to go back on the power.

But I was assuming that considerations such as speed limits and safety
(there may be a bend as the hill goes from downhill to uphill) require you
to restrict your speed with some form of braking. Now that braking can be
conventional disc brakes, engine braking or regenerative braking.

I was querying the statement that coasting downhill in gear uses more fuel
than doing it in neutral, and you've agreed with me that it doesn't *while
you are going downhill*.

I agree that regenerative braking is the best because the energy lost as
heat in brakes or engine compression is put back into the battery for
regenerative.


I'm surprised that the assertion about optimal engine speed resulting in
better fuel economy isn't true. Maybe you do get better economy, but this is
ffset by the losses in converting mechanical (kinetic) energy to electrical
energy in a generator and then back to mechanical in the motors.

On May 8, 7:33*am, " >
wrote:
>
> Idiot...the whole THING is about regenerative braking.

I really had my doubts about your theory until you started calling
people names.

Now I'm convinced.

Richard Henry wrote:
> On May 8, 7:33 am, " >
> wrote:
>>
>> Idiot...the whole THING is about regenerative braking.
>
> I really had my doubts about your theory until you started calling
> people names.
>
> Now I'm convinced.

Yeah, that's the way we do things around here. We find it to be a superior
way of arriving at the truth.

--
Wayne Dobson
AKA "Dobbie The House Elf"

> Ah, I see what you're saying: you're prepared to accelerate down the hill to
> a speed above what you were doing on the flat, and let that carry you part
> of the way up the hill on the far side. Yes, I agree: coating in neutral
> will involve less braking so you'll go further up the other side before you
> have to go back on the power.

Yes, accelerate insofar as highway RPM engine pumping losses are a
deceleration.

There are many cases where you will actually have to use gas on a
downhill to overcome compression, whereas if you were coasting, you'd
be at idle and a constant speed. The hybrid powertrains recognize
this and shut the gas motor off.

> But I was assuming that considerations such as speed limits and safety
> (there may be a bend as the hill goes from downhill to uphill) require you
> to restrict your speed with some form of braking. Now that braking can be
> conventional disc brakes, engine braking or regenerative braking.

I am not talking about just rolling to a higher speed. Find a minor
downgrade. Drive down it at speed...then put your car into neutral
and check your consumption meter in both cases.

> I was querying the statement that coasting downhill in gear uses more fuel
> than doing it in neutral, and you've agreed with me that it doesn't *while
> you are going downhill*.

Of course, zero throttle is zero throttle.

But many downgrades require nonzero throttle, as they are mild.

> I'm surprised that the assertion about optimal engine speed resulting in
> better fuel economy isn't true. Maybe you do get better economy, but this is
> ffset by the losses in converting mechanical (kinetic) energy to electrical
> energy in a generator and then back to mechanical in the motors.

I didn't say that ASSERTION wasn't true, I said that the assertion
that the hybrids do so well MPG-wise was because of "optimal engine
speed." That's categorically incorrect.

Trav

> I really had my doubts about your theory until you started calling
> people names.
>
> Now I'm convinced.

If you want, you may test-drive a Prius.

I am surprised more people haven't.
Their conservation program teaches you a lot about where cars waste
fuel. ANY time the car would be better served by gravity, the Prius
shuts off the engine. Even on the freeway. I have been doing 70mph
in one and have had it shut gas power off. There was no need for it
as gravity was more than sufficient. And, if my speed goes too high,
I drag the brakes to put some of the excess into the batteries.

That is how hybrids work.

As far as my insulting people, I have 2 defenses: 1, that is just how
we talk around here, 2, he actually was an idiot. Somebody
crossposted a reply along the way.

Trav

wrote:
>> Ah, I see what you're saying: you're prepared to accelerate down the
>> hill to a speed above what you were doing on the flat, and let that
>> carry you part of the way up the hill on the far side. Yes, I agree:
>> coating in neutral will involve less braking so you'll go further up
>> the other side before you have to go back on the power.
>
> Yes, accelerate insofar as highway RPM engine pumping losses are a
> deceleration.

It isn't at all. So that would be insofar as not at all.

--
Wayne Dobson
AKA "Dobbie The House Elf"

wrote:
>> I really had my doubts about your theory until you started calling
>> people names.
>>
>> Now I'm convinced.
>
> If you want, you may test-drive a Prius.
>
> I am surprised more people haven't.
> Their conservation program teaches you a lot about where cars waste
> fuel. ANY time the car would be better served by gravity, the Prius
> shuts off the engine. Even on the freeway. I have been doing 70mph
> in one and have had it shut gas power off. There was no need for it
> as gravity was more than sufficient. And, if my speed goes too high,
> I drag the brakes to put some of the excess into the batteries.
>
> That is how hybrids work.
>
> As far as my insulting people, I have 2 defenses: 1, that is just how
> we talk around here, 2, he actually was an idiot.

Which, naturally, strengthened your argument, as it might not have enough
strength against sensible people.

--
Wayne Dobson
AKA "Dobbie The House Elf"

> > Yes, accelerate insofar as highway RPM engine pumping losses are a
> > deceleration.
>
> It isn't at all. So that would be insofar as not at all.
>
> --
> Wayne Dobson
> AKA "Dobbie The House Elf"

What? The engine's combustion cycle involves decelerations during 3
of the strokes, you ****ing moron. Under zero throttle, the
mechanical valvetrain is still operating. This is how engine braking
WORKS, you freakin idiot. The engine is a glorified air pump.

Do you even drive a car? The work involved in compressing the air, as
well as drawing it in and moving it out constitute decelerations.
With no power stroke under zero throttle, the engine is a BRAKE, IOW,
a deceleration. Any idiot can shift his car into neutral and figure
this out immediately.

I suppose you haven't figured out why the signs say "steep grade,
trucks use low gears"?

Trav

> wrote in message
...
|> > Yes, accelerate insofar as highway RPM engine pumping losses are a
| > > deceleration.
| >
| > It isn't at all. So that would be insofar as not at all.
| >
| > --
| > Wayne Dobson
| > AKA "Dobbie The House Elf"
|
| What? The engine's combustion cycle involves decelerations during 3
| of the strokes, you ****ing moron.

What does it do on the fourth, let off firecrackers?

On May 8, 8:12*pm, "Androcles" > wrote:
> > wrote in message
>
> ...
> |> > Yes, accelerate insofar as highway RPM engine pumping losses are a
> | > > deceleration.
> | >
> | > It isn't at all. *So that would be insofar as not at all.
> | >
> | > --
> | > Wayne Dobson
> | > AKA "Dobbie The House Elf"
> |
> | What? *The engine's combustion cycle involves decelerations during 3
> | of the strokes, you ****ing moron.
>
> What does it do on the fourth, let off firecrackers?

Yeah...that's called the power stroke, you idjit. That's the one
where the gasoline blows up.

Trav