Mike G wrote:
"Dave" wrote in message
...
On 7 Aug, 12:25, "Mike G" wrote:
"shazzbat" wrote in
message

...
Change gear when it feels/sounds right, which you'll pick up
very quickly. The rev counter is a pretty toy.

Yup. It isn't that long ago to a time when tachometers were
only
fitted in 'sports' or more expensive cars as std equipment.
They have little practical use.
Mike.

I really disagree. I can make a much more acurate decision
about when
to change gear with a rev counter than with my ear. At the
bottom of
the rev range this probably translates to a lower incidence of
head
gasket failures, at the top of the rev range it definatly means
higher
performance.

At the top of the rev 'range' maybe. but peak revs on a tacho is
seldom the right time to change gear for maximum performance.
As far as lower revs are concerned, you shouldn't need a tacho to
tell you when revs are too low.
IME you can hear and feel when to change gear, up or down. I
can't say I've ever needed to refer to a tacho, even when driving
briskly.

Yes, I agree with you. It's been a while since I had a car without a tacho
in it, but I rarely look at it, if ever. Might catch it out of the corner of
my eye when I check the speedo, but I never pay much attention to it. I can
tell by noise and feel whether I need to change gear or not.

Mike P

Dave wrote:
On 7 Aug, 13:49, "Mike P" wrote:
Dave wrote:
On 7 Aug, 12:25, "Mike G" wrote:
"shazzbat" wrote in message

...
Change gear when it feels/sounds right, which you'll pick up
very quickly. The rev counter is a pretty toy.

Yup. It isn't that long ago to a time when tachometers were only
fitted in 'sports' or more expensive cars as std equipment.
They have little practical use.
Mike.

I really disagree. I can make a much more acurate decision about
when to change gear with a rev counter than with my ear. At the
bottom of the rev range this probably translates to a lower
incidence of head gasket failures

How does it stop your headgasket failing?

Mike P

I am not sure, but I was told that using lots of throtle at low revs
caused the head gasket to fail. Once I stopped doing this I stopped
getting head gasket failures (and I had had a few). A rev counter
allows me to make this decision more easily and acuratly. I could be
wrong of course, but it seems to make sence to me. I am certain about
the other end of the rev range.

I've not heard that before. I've had a couple of cars blow headgaskets, but
they had been seriously caned and badly maintained. Oh, and one was a FIAT
Punto 1.2, so it goes without sayign that the HG failed on that.

Mike P

On 7 Aug, 14:17, "Mike G" wrote:
"Dave" wrote in message

...





On 7 Aug, 12:25, "Mike G" wrote:
"shazzbat" wrote in
message

...
Change gear when it feels/sounds right, which you'll pick up
very quickly. The rev counter is a pretty toy.

Yup. It isn't that long ago to a time when tachometers were
only
fitted in 'sports' or more expensive cars as std equipment.
They have little practical use.
Mike.

I really disagree. *I can make a much more acurate decision
about when
to change gear with a rev counter than with my ear. *At the
bottom of
the rev range this probably translates to a lower incidence of
head
gasket failures, at the top of the rev range it definatly means
higher
performance.

At the top of the rev 'range' maybe. but peak revs on a tacho is
seldom the right time to change gear for maximum performance.

In almost every car I have driven the maximum power is achived just
before the rev limiter. The only exceptions, other than the very few
that did not have a rev limiter, were the 2 rovers I have owned, where
the power did decline as you approached the red line, to the point
where there was no more acceleration possible in that gear. I assumed
this was because they were fitted with some sort of "soft" rev limiter
where fuel and / or air was gradually restricted as the revs
increased, rather than abruptly stoped at some certain point on all
other cars.

I have heard that on old cars the size of the inlets were the limiting
factor at high revs, and so power would drop. I have never had
anything like that. What sort of cars do you drive, and were is their
peak power?

As far as lower revs are concerned, you shouldn't need a tacho to
tell you when revs are too low.

Possibly. I did used to use very low revs, in the assumption it was
good for the pocket, and now I may have gone too far the other way and
am too hesitant to use the bottom of the rev range. I will not use
full throtle well above the point that you can feel the engine
complain.

IME you can hear and feel when to change gear, up or down. I
can't say I've ever needed to refer to a tacho, even when driving

I guess it is personal preference. I sort of learnt to drive in
tractors, where you have a tacho but no speedo, so I use the tacho in
preference to the speedo. YMMV.

Dave wrote:

I really disagree. I can make a much more acurate decision about when
to change gear with a rev counter than with my ear.

May I humbly suggest that you might benefit from fitting a vacuum gauge?
I was quite surprised by the results when I fitted one to my Vitesse.
Seems I'd been in the habit of changing gear at far lower revs than I
should have been for greatest efficiency.

On 7 Aug, 16:21, Willy Eckerslyke wrote:
Dave wrote:
I really disagree. *I can make a much more acurate decision about when
to change gear with a rev counter than with my ear.

May I humbly suggest that you might benefit from fitting a vacuum gauge?
I was quite surprised by the results when I fitted one to my Vitesse.
Seems I'd been in the habit of changing gear at far lower revs than I
should have been for greatest efficiency.

You certainly can, especially if you elaborate a bit. I guess you
mean something like http://www.iwemalpg.com/Vacuum_gauge.htm ? That
seems to be a tuning tool, I am not sure how it is relavent to gear
change timing as he does not seem to have it fitted while driving but
while setting the timing.

Dave wrote:
On 7 Aug, 16:21, Willy Eckerslyke wrote:
Dave wrote:
I really disagree. I can make a much more acurate decision about when
to change gear with a rev counter than with my ear.
May I humbly suggest that you might benefit from fitting a vacuum gauge?
I was quite surprised by the results when I fitted one to my Vitesse.
Seems I'd been in the habit of changing gear at far lower revs than I
should have been for greatest efficiency.

You certainly can, especially if you elaborate a bit. I guess you
mean something like http://www.iwemalpg.com/Vacuum_gauge.htm ?

Yup, that's the kind of thing.

That
seems to be a tuning tool, I am not sure how it is relavent to gear
change timing as he does not seem to have it fitted while driving but
while setting the timing.

No you have them permanently fitted. Or at least you used to on old
cars. They were sometimes marketed as economy gauges, or words to that
effect. Hence the "poor" "fair", etc on the illustration. The aim was to
keep the needle in the green by changing gear at the right times and
moderating your use of the throttle.

"Willy Eckerslyke" wrote in message
...
Dave wrote:
On 7 Aug, 16:21, Willy Eckerslyke wrote:
Dave wrote:
I really disagree. I can make a much more acurate decision about when
to change gear with a rev counter than with my ear.
May I humbly suggest that you might benefit from fitting a vacuum gauge?
I was quite surprised by the results when I fitted one to my Vitesse.
Seems I'd been in the habit of changing gear at far lower revs than I
should have been for greatest efficiency.

You certainly can, especially if you elaborate a bit. I guess you
mean something like http://www.iwemalpg.com/Vacuum_gauge.htm ?

Yup, that's the kind of thing.

That
seems to be a tuning tool, I am not sure how it is relavent to gear
change timing as he does not seem to have it fitted while driving but
while setting the timing.

No you have them permanently fitted. Or at least you used to on old cars.
They were sometimes marketed as economy gauges, or words to that effect.
Hence the "poor" "fair", etc on the illustration. The aim was to keep the
needle in the green by changing gear at the right times and moderating
your use of the throttle.
==================================================

I never ever look at the rev counter unless I'm caning it, just to see whats
left in it. It's totally unnecessary IMHO.

--
Les Ross
Certified by a
Professional

"Marlon" wrote in message
...

Hi all,
having just swapped an automatic for a manual, I now have gears and
a tachometer as controllable variables in my driving.
So it occured to me that I've never really done that bloke thing of
knowing about rev ranges, when "best" to change gear (other than when it
feels "right"), and such like.
So.... for instance, given there's an obvious upper range to be
avoided (as indicated by red lines), is there actually a practical lower
limit (obviously without stalling)? Is there a "sweet spot" in between?
Is it possible to determine at what amount of revs a particular
engine is theoretically "best" at - and would "best" be defined in terms
of fuel economy or some other operating measure?
I'd imagine that any such measures would vary according to the
vehicle (& engine size).
Is it obvious where I'm coming from, or should I just go get on with
enjoying driving without worrying about such stuff

In general, try and stay above 1500 revs. You can get away with lower revs
if you're trundling at low speed and have a relatively large engine, but
labouring the engine is a bad thing. Labouring is indicated by funny
noises...

"Marlon" wrote in message
...

Hi all,
having just swapped an automatic for a manual, I now have gears and
a tachometer as controllable variables in my driving.
So it occured to me that I've never really done that bloke thing of
knowing about rev ranges, when "best" to change gear (other than when it
feels "right"), and such like.


When it 'feels' right is about right.

Rev counters are pretty good for telling you if your engine is idling
properly.
And of course if you're hypermiling and want to watch for when DFCO or other
things cut in and out!

"Dave" wrote in message
...
On 7 Aug, 14:17, "Mike G" wrote:
"Dave" wrote in message

...





On 7 Aug, 12:25, "Mike G" wrote:
"shazzbat" wrote in
message

...
Change gear when it feels/sounds right, which you'll pick
up
very quickly. The rev counter is a pretty toy.

Yup. It isn't that long ago to a time when tachometers were
only
fitted in 'sports' or more expensive cars as std equipment.
They have little practical use.
Mike.

I really disagree. I can make a much more acurate decision
about when
to change gear with a rev counter than with my ear. At the
bottom of
the rev range this probably translates to a lower incidence
of
head
gasket failures, at the top of the rev range it definatly
means
higher
performance.

At the top of the rev 'range' maybe. but peak revs on a tacho
is
seldom the right time to change gear for maximum performance.

In almost every car I have driven the maximum power is achived
just
before the rev limiter.

I seriously doubt that. IME max power can be as much as 1k revs
below peak revs. Max torque below that.

The only exceptions, other than the very few
that did not have a rev limiter, were the 2 rovers I have owned,
where
the power did decline as you approached the red line, to the
point
where there was no more acceleration possible in that gear. I
assumed
this was because they were fitted with some sort of "soft" rev
limiter
where fuel and / or air was gradually restricted as the revs
increased, rather than abruptly stoped at some certain point on
all
other cars.

I have heard that on old cars the size of the inlets were the
limiting
factor at high revs, and so power would drop. I have never had
anything like that. What sort of cars do you drive, and were is
their
peak power?

On my car, 528i BMW. Max revs can go to 6,500 for short periods,
about 6,250 sustained. Max power is delivered at 5,300, max
torque at 3,950.
Mike.

As far as lower revs are concerned, you shouldn't need a tacho
to
tell you when revs are too low.

Possibly. I did used to use very low revs, in the assumption it
was
good for the pocket, and now I may have gone too far the other
way and
am too hesitant to use the bottom of the rev range. I will not
use
full throtle well above the point that you can feel the engine
complain.

IME you can hear and feel when to change gear, up or down. I
can't say I've ever needed to refer to a tacho, even when
driving

I guess it is personal preference. I sort of learnt to drive in
tractors, where you have a tacho but no speedo, so I use the
tacho in
preference to the speedo. YMMV.