Doh

Memo to self:

After riding your slightly undergeared BMW for a few weeks, when you
hop onto your slightly overgeared Ducati, check to see that you really
are in top gear, not fourth.

Ten miles of the M25 done in the wrong gear is not a good way of
burning fuel.

 

I've done that loads on the 10R, but the bike is geared for 100 in 1st,
so being in 3rd or 4th isn't all bad.

 

<pedant mode on> ITYM it's a very good way of burning fuel........<pedant
mode off>

Mark

 

I haven't got the knowledge to disprove this but are you saying that you
will get similar economy on your 10R at 70 mph in 1st as you would top?

Mark

 

Sucking his keyboard for inspiration, Champ typed:

I once drove a 4.6 Rangie for about 100 miles on the autoroute in 3rd
(locked it down for a hilly stretch [1] and forgot to put it back into D)
and to my surprise it made no difference whatever to the fuel consumption.
Bastard 14mpg in D, bastard 14mpg in 3. I guess the increase in revs is
offset by the lower pressure on the loud pedal.

[1] Towing, and it had a tendency to hunt between 3 and 4 on the upgrades.

 

So the only point of an old fashioned car 'overdrive' was reduced noise
in the cabin then?
--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

Still trying to understand this.........

I thought max mpg was usually around peak torque?

 

A terrible thing for me to suggest and totally out of keeping with UKRM,
but the next time I take the cheerful czech out on a nice clear *flat*
section of motorway I will experiment. Engage cruise control and set for
a steady speed that will be OK in either 6th or 5th (or even 4th) and
watch the 'instantaneous' fuel consumption display in each gear.

--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

Yes, I'll do the same.

 

I had an old 3.5 Rangie with the Chrysler 3-speed autobox, so I never
bothered locking it in any gear. But it did 15mpg whether I drifted around
at 35mph or ranted it up to Scotland on the motorway.

Clunked, but never hunted.

 

In communiqué
<1i6v3j6.nlwujsb0v378N%>, The

It will have to be at a realistically speed though naturally. Below 60
or so I suspect 6th might burn more than 5th.

I certainly cog down when going up a really steep hill, particularly
when towing. A quick switch to instant mpg when allowing the TDi ECU to
open up the taps hard in 6th to maintain speed displayed an impressively
low figure.

--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

<sits back and opens a bag of popcorn>


--
Beav

VN 750
Zed 1000
OMF# 19

 

You'll have to ride very close to him.

 

On my old MGB, it dropped the revs into a slightly more torquey part
of the range.

 

Well for you personally that's a given. They used to *claim* reduced
wear and better economy from lower revs at 'cruising speed' [1]. Neither
of which is of great importance to you I suspect.

The gas conversion V6 Transit I used to travel in to many hill climbs
had a switch selected overdrive. Its owner, who was parsimonious enough
to have probably have conducted comparison tests, always insisted it was
selected ASAP on our long motorway treks to the west country.

[1] An alien concept for "if in doubt, flat out" UKRM.
--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

Not at all, we are familiar with both tautology and the concepts of the
oxymoronism.

 

Reduced wear certainly, I'd have thought, from fewer revs.

 

Ooop, I think you are _very_ much mistaken. I've experimented somewhat
with the cars, trying the same speed on the same road in different
gears, and without fail the higher gear give better fuel economy at a
constant speed on the flat, this only starting to fail if you need to
accelerate or give it gas on an uphill slope.

--
_______
..'_/_|_\_'. Ace (bdotrogers a.t compaqnet.fr)
\`\ | /`/ DS#8 BOTAFOT#3 SbS#2 UKRMMA#13 DFV#8 SKA#2 IBB#10
`\\ | //'
`\|/`
`

 

<gives in to temptation to google>

Well these people should expect a call from Trading Standards then.

http://www.overdrives.co.uk/landr2.htm

Perhaps Landrovers are a special case?

--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

Sucking his keyboard for inspiration, Champ typed:

On the principle mentioned earlier in the thread of energy in - energy out,
the only benefit I can see is in reduced friction losses in the engine (and
any part of the transmission upstream of the overdrive, if fitted). So any
difference is going to be small, and probably smaller than measurable in
everyday use.

On a slightly different point, I am surprised at how little the fuel
consumption figure (as given by the OBC) goes down in slow-moving traffic.
Common sense would suggest that crawling in 1st at 5mph in a mway snarl-up
would wreck mpg figures, but it seems to knock it down very little. I
suppose the decrease in efficiency is balanced by a reduction of aerodynamic
and rolling losses to almost zero.