Pet Peeve: Tachometers

[Hokiefyd]

This is a pet peeve of mine; I’m not sure why…presumably it’s because so few get it right.

A gauge is supposed to be labeled with what that that gauge is displaying. A speedometer is labeled MPH; literally, because it tells you Miles Per Hour. A voltmeter is labeled V; literally because it tells you Volts. An oil pressure gauge is usually labeled PSI (or sometimes kPa); literally, because it tells you Pounds per Square Inch.

Why, then, are most tachometers labeled RPM x 1000? The gauge does not give you Revolutions Per Minute multiplied by 1000. Revolutions Per Minute multiplied by 1000 would read 700,000 on most cars. The gauge, in fact, gives you Revolutions Per Minute divided by 1000; the correct label is RPM / 1000 or something to that effect.

The only one I’ve seen done correctly is in an old Chevelle, which was RPM / 100 (for a tachometer that counts 10, 20, etc).

Does anyone here own a tachometer that is labeled correctly? Neither of mine are.

 

[bowlofturtle]

maybe the euro cars....

none of mines, maybe on my motorcycle.

 

[dishdude]

Some VWs are labeled RPM/100.

 

[RF Overlord]

The tach in the Mercury Marauder reads in single digits times 1000, so that would be correct.

 

[redhat]

The tach in my Accord shows 0-8 and in the center says x1000/min.

 

[javacontour]

How are they not labeled correctly?

If the numbers on the tach are 1,2,3,4,5,6,7 and it indicates RPM X1000 then 1 = 1000 RPM and so on.

Just as the tach you have in your image lists 10,20,30 and then indicates the scale is RPM x 100.

I always found the RPM X 100 was odd and prefer the single digits on the tach.

But it's just a matter of preference. They both measure exactly the same thing.

 

[ls1mike]

No different, this is the WS6. 1000 x the single digit is the RPM at that point in time.

 

[Colt45ws]

I see what is going on.
They are labeled telling you what to do to get the real RPM. In the WS6 gauge above you have to multiply the number indicated by 1000 to get actual RPM. You are right, that what it is doing is dividing RPM by 1000.

Its probably just due to people not able to maths very good so manufactures just label it this way. Now its so common no one thinks about it.

 

[Quattro Pete]

The tachs on both our cars say "1/min x 1000".

I think the point is that they're giving you a formula to calculate the actual RPM. Another words, take the number from the gauge and multiply it by 1000 to find out current RPM. I don't see anything wrong with this approach, personally. But yes, technically the label should be telling you what the gauge reports and not what to do with it.

 

[ls1mike]

Either way, I just don't keep it in the red for extended periods of time.

 

[Schmoe]

????

 

[Quattro Pete]

Originally Posted By: javacontour
I always found the RPM X 100 was odd and prefer the single digits on the tach.

Same here. Plus I've heard of instances where people would confuse the speedo with the tach since both were scaled in similar numbers.

 

[ls1mike]

Originally Posted By: Schmoe
????


You know in the red zone of the Tach? I usually like to try and stay below that.

 

[ls1mike]

Originally Posted By: Quattro Pete
Originally Posted By: javacontour
I always found the RPM X 100 was odd and prefer the single digits on the tach.

Same here. Plus I've heard of instances where people would confuse the speedo with the tach since both were scaled in similar numbers.

Funny story...My ex wife's grandma had a 2.8 Cadillac Cimarron.
Here is the dash...

She drove from Long Island to upstate NY when she first purchased it. When she got to the house, she told my father-in-law and I that the car wouldn't go over 30 mph and it used too much gas. We were puzzled so took it for a ride.

She was watching the tach. Not sure how fast it was because it was years ago, but it explained the record time she made driving up state. She was driving 3000 rpm with a 2.8 in overdrive. Had to be at least 95 mph.

 

[Colt45ws]

Originally Posted By: ls1mike
Originally Posted By: Schmoe
????


You know in the red zone of the Tach? I usually like to try and stay below that.

Bah. You can probably run that to at least 6.5. Its more of a guideline, anyway.

 

[Quattro Pete]

My big pet peeve is coolant temp gauges with massive dead ranges in the middle. For example, this one won't budge from 12 o'clock even if the temp fluctuates from 75C to 115C (167F to 239F).

 

[friendly_jacek]

Originally Posted By: Hokiefyd

Does anyone here own a tachometer that is labeled correctly? Neither of mine are.


Technically, you are right, but it would be confusing to most people.

IMHO, there should be full thousands listed on the dial. How much does it cost to print some more zeros?

Alternative, we should go with SI system and express them per second.

 

[ls1mike]

Quote:
Bah. You can probably run that to at least 6.5. Its more of a guideline, anyway.
banana


You are right. Let me tell you a little secret. I have the rev limiter removed on that car...

 

[Quattro Pete]

Originally Posted By: friendly_jacek
IMHO, there should be full thousands listed on the dial. How much does it cost to print some more zeros?

I don't think it's a cost cutting issue. It would just look cluttered and less legible with all those extra digits there.

 

[spackard]

Well, how's about the European fuel gauge -
0/1 (= empty)
1/2 (= half full)
1/1 (= full)

It should be:
0/2
1/2
1/2
So I can see I either have zero of something, one of something, or two of something. Quit switching the denominator.

Would it really make sense to put:
0.0
0.5
1.0
which is what the 0/1, 1/2, 1/1 looks like digitally.