Pet Peeve: Tachometers

[ls1mike]

Now you did it. You made go take pictures of the Truck and Buick.
So the Buick, much to my surprise is how you like to see it.
Never much cared before...Thanks!...I think

The truck, I guess it does not care either way. Although displayed like the Trans Am, you can run that bad boy at 6000 rpm or is it 6 or is 6/1000. Anyway no redline so hammer down.

 

[TFB1]

Well in 46+ years of vehicle ownership, I've never had any issue figuring out 3 X 1000 = 3000 RPM...

BTW my '88 T-Bird and '07 Grand Marquis read in single digits and are both RPM X 1000, while the '69 428CJ Fairlane that reads in 10s is marked RPM x 100...

 

[Tegger]

Originally Posted By: ls1mike
Originally Posted By: Tegger

And I can't ever remember seeing a tach with "RPM x 1000" on it.


Here it is again...

Aha, the problem is getting clearer now.

Somebody seems to be thinking erroneously that the notation on the tach is meant to be a one-line mathematical expression, which common-sense shows to be obviously untrue. The notation is plainly meant to be read as two separate lines, each conveying different information.

I'm taking the top line to mean, "this is a text description of what this gauge displays",
and the second line is saying, "this is the arithmetic that is to be applied to the raw number shown by the gauge needle".

 

[Tegger]

Originally Posted By: ls1mike

This is correct. The gauge notation is on a single line, obviously meant to be read as an expression.

The number shown on the tach IS the RPM, just divided by 1000, which is why the zeroes are missing.

 

[yonyon]

Originally Posted By: Quattro Pete
Originally Posted By: eljefino
Also note the yellow zone on the tach starting at "55"; remember, we had to circle or otherwise emphasise 55 MPH per law back then.

But why was it denoted on the tach? You'd never come anywhere close to 5500 rpm if you were to stay at 55 mph.


Don't be too sure about that. I'm driving around with a 2.8L and when the tach hits 55 (yellow) that's about the speed where washer fluid starts leaking out the nozzles onto the windshield. It's definitely not up to 55 MPH yet. Maybe the yellow is supposed to make you think about peeing, which is what the car is about to do to itself?

 

[Tegger]

Originally Posted By: TallPaul
I really like this aftermarket tach I had in my old F150 4.9L

What irritates me is tachs without a redline. Many Fords over the years have had a 0-6000 rpm tach with no redline.
Can only figure they don't want to stock more than one gauge face.

I once had an Auto Meter aftermarket tach with the same apparently-incorrect notation. I've never seen an OE tach with that incorrect notation.

The Auto Meter had a red needle that could be repositioned via a knob to represent the redline.

 

[ls1mike]

Originally Posted By: Tegger
Aha, the problem is getting clearer now.

Somebody seems to be thinking erroneously that the notation on the tach is meant to be a one-line mathematical expression, which common-sense shows to be obviously untrue. The notation is plainly meant to be read as two separate lines, each conveying different information.

I'm taking the top line to mean, "this is a text description of what this gauge displays",
and the second line is saying, "this is the arithmetic that is to be applied to the raw number shown by the gauge needle".

That is how I read it.

Man, must be the heat in North America right now or everyone is super bored.

 

[ls1mike]

Originally Posted By: yonyon
Originally Posted By: Quattro Pete
Originally Posted By: eljefino
Also note the yellow zone on the tach starting at "55"; remember, we had to circle or otherwise emphasise 55 MPH per law back then.

But why was it denoted on the tach? You'd never come anywhere close to 5500 rpm if you were to stay at 55 mph.


Don't be too sure about that. I'm driving around with a 2.8L and when the tach hits 55 (yellow) that's about the speed where washer fluid starts leaking out the nozzles onto the windshield. It's definitely not up to 55 MPH yet. Maybe the yellow is supposed to make you think about peeing, which is what the car is about to do to itself?


Everyone hated that Cadillac, you know badge engineering, but it was basically a Z34. It moved out pretty good...For the 80's

 

[TallPaul]

Originally Posted By: 01rangerxl
Most Ford engines "redline" past 6000 RPM, which is why it is not displayed on the tach. Your truck is electronically limited to 6250 RPM. It would need to be turning faster than that to do any damage or make the valves float.

My pushrod 4.0 Explorer had the same gauge cluster, but did have a redline on the tach at I think 4500 or 5000 RPM.


Well the old 4.9L six should never exceed 4000 rpm, in fact 3800 is enough, just no advantage above that. But about my current truck, the 2001 Ranger 2.3L DOHC 16-valve, I think you are right because I hit the rev limiter once and it was just a tad above 6000.

At any rate, that 2.3 DOHC is going to be quickest if the 1-2 is at 5500 rpm, and the 2-3 and 3-4 around 5200, so my calcs show. Here is a fun vid of the ranger on a freeway ramp run:

 

[TFB1]

Most non high performance Fords will cut the fuel at 6250 RPMs...

The tach in my '88 Thunderbird is yellow lined at 4500 and red at 5000... With aftermarket heads, chip and several other mods I regularly spun that stock short block well past 6K RPM with no issues... Well it had head gasket problems but I attribute that to the 150Hp shot of nitrous...

 

[artificialist]

I am used to Japanese cars, where it says r/min x1000

This made me think of something that was funny about mom's 1985 Nissan Maxima and its huge fancy analog cluster and a Tron game grid in the background. It had an oil pressure gauge, and it said lb/in^2 instead of PSI. In 3rd grade, I learned about square inches, and I finally understood what that weird gauge meant. There were digital displays on some versions of the 85-88 Maxima, but I never actually rode in one that had that digital display.

The Maxima from those days had a redline of 6000 RPM. Some simply used 6000 RPM as a redline, others had a candy-cane looking thing between 5500 and 6000 RPM.

The Nissan Z31 300ZX had a similar analog display, using lb/in^2 for oil pressure, and turbo models had lb/in^2 for boost pressure.

I don't remember exactly how the Z31 300ZX digital display worked. All I remember was that it was complex, expensive, and looked like it belonged in Knight Rider or Tron.

I just thought of another thing that could make this tachometer discussion lengthen. How many increments between numbers on your tach?

 

[opus1]

Originally Posted By: davebarnum

Google went outside and checked for you. You have a tach which displays "x1000 rpm."

Thanks. I had to run some errands so I took the Sonata and was going to post an update, but I see that's been resolved for me.

 

[Hokiefyd]

Originally Posted By: ls1mike
Now you did it. You made go take pictures of the Truck and Buick.
So the Buick, much to my surprise is how you like to see it.
Never much cared before...Thanks!...I think

Nice! Three cheers for the Buick!

Which is really puzzling...various GM tachometers from much the same era are labeled differently depending on the brand.

 

[yonyon]

Buick probably had to consider the possibility of a 107 year old man armed with a golf club taking offence at the incorrect label and raising [censored] about it in the showroom.

 

[ls1mike]

Originally Posted By: yonyon
Buick probably had to consider the possibility of a 107 year old man armed with a golf club taking offence at the incorrect label and raising [censored] about it in the showroom.

Dude, thank you for that laugh. I spit my cheese and crackers out! I love my supercharged 3800 even if it is wrapped in a Buick. Which is pretty comfortable.

 

[ls1mike]

Originally Posted By: Hokiefyd
Originally Posted By: ls1mike
Now you did it. You made go take pictures of the Truck and Buick.
So the Buick, much to my surprise is how you like to see it.
Never much cared before...Thanks!...I think

Nice! Three cheers for the Buick!

Which is really puzzling...various GM tachometers from much the same era are labeled differently depending on the brand.

Simple an engineer designed that tach.

 

[ls1mike]

This thread is full of happiness. I like it.

 

[Vikas]

Was Jason here when were discussing that math problem? What was your answer? 1 or 9??

 

[Hokiefyd]

Originally Posted By: Vikas
Was Jason here when were discussing that math problem? What was your answer? 1 or 9??


Yes, I was. That was puzzling; different graphing calculators computed it differently.

This stuff makes me curious. My 1997 SLS and my 2001 STS both said "RPM X 1000" on one line. Mike's Chevrolet and Pontiac do as well (but on two lines). But his Buick is different. I have to wonder what that conference room discussion was like, and how the Buick's gauge came to be labeled differently from the other GM gauges.

 

[Hootbro]

Originally Posted By: 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).

They went to those gauges because most people cannot read a active gauge properly and would freak every time they see the temp occasionally climb but still be within service limits and take it in for an undue service check.