Lawrie is dead right. Those "shift lights" on new cars are completely
idiotic, if you think of them as a "redline". My wife's Metro doesn't
have a tach, but the light would have you shifting that 1.0 liter
3-banger at what seems to be around 2500rpm. At that rate you'd be in 4th
gear at 32mph -- not exactly the way to achieve good (or even mediocre)
acceleration, and very tough on the engine. I look at the light as an
indication of what gear to be in at a sustained cruise, but ignore it for
acceleration purposes. I suppose it would be useful during the Mobil
Economy Run (anybody remember that?).
For some historical perspective, 1960s Chryslers used to have a gauge
called a "Performance Indicator" (actually a vacuum gauge). It was marked
with two regions: "Economy" and "Power". In order to keep the needle in
the Economy range, one had to use part throttle only, and shift well
short of the power peak (or more likely, let the automatic transmission
shift up). Of course, it was much more fun to see how deep in the Power
range one could bury the needle...
Lawrie Alexander had this to say:
>Nina,
>
>Yours are good driving habits - you've been shifting in the best part of a
>B's engine's powerband to give adequate power combined with reasonable fuel
>economy.
>
>The Saturn's shift light has, however, a different purpose - to help owners
>achieve the fuel economy advertised on the sticker that graced a window when
>the car was new. I haven't driven a Saturn but my guess is that, driven the
>way you drive your BGT, it would be a whole lot more fun but use a bit more
>gas.
>
>Lawrie
>
>-----Original Message-----
>From: Nina Barton <ninab@scoresheet.com>
>To: mgs@autox.team.net <mgs@autox.team.net>
>Date: Friday, November 10, 2000 10:03 PM
>Subject: somebody explain shifting and RPM to me
>
>
>>Hi List,
>> I have always driven my MGB, and other cars, in the following
>>manner. Start from stop, rev up to what seems an appropriate level
>>(usually 3500 or so in the BGT), shift, rev up to somewhere around the same
>>level, shift again, etc. I recently had problems with the troop carrier (a
>>93 Saturn) which turned out to be that the bulb on the dash showing optimal
>>shift for premium gas mileage had burned out. I didn't know it was there,
>>as the previous owner had taped over it. It has now been uncovered, and
>>besides being a pain in the a**, I notice that it suggests that I shift
>>from first to second around 3000 Rpm, second to third at 2500 Rpm, and
>>third to fourth at 2100 Rpm. Why? It seems like I'm not going fast enough
>>in the car when the shift light comes on, much of the time, and it goes
>>against my whole driving style. If one of the knowledgeable people on this
>>list could explain why lugging your engine is good for the car, I'd like to
>>know. Thanks, Nina
>
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the red one with the silver bootlid.
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