Tachometer Users, please check these speeds

[SuperGeek]

Analog speedometers err high so that if you get a speeding ticket, it's because you really were speeding, and not because the odometer said you were going 60 when you were doing 62. They're needle against background, so angle of view also plays a factor. If you're 5'2" the speed might look 1-2mph different than if you're 6'3".

[Old smart]

Originally Posted by Allargando DiFortissimo

Howdy,
Lurked for quite a while, now for my 1st post.

If you have a genuine Smart tachometer (pod) installed, how about take a piece of paper with you sometime and answer these questions for me.

When driving in 5th gear,

mph @ 2,000 rpm?
mph @ 3,000 rpm?
mph @ 4,000 rpm?

Also, the exact revs (as close as you can tell) in 5th gear when the speedo reads 60mph.

Bear in mind, I don't want theoretical numbers (I've already figured those). I'm interested in what Smart's speedo says against Smart's tachometer.

Thanks, going out to drive now.

jrc in SC

Here's what I got:

2k RPM - 40.5 MPH
2500 - 53.0 MPH
3k RPM - 62.0 MPH
3500 - 73.0 MPH
4k RPM - not attempted

additionally,

40 MPH - 1950 RPM
50 MPH - 2400 RPM
60 MPH - 2900 RPM
70 MPH - 3300 RPM

I didn't feel that this wet Memorial Day weekend was the time to experiment with 4k RPM in 5th, especially in VA and especially by an ex-patriot New Englander. So....

I graphed the nine data points above on the same rectangular graph and extrapolate that 4k RPM equates to 85 MPH**, and 80 MPH equates to 3800 RPM.

By instruments and Mk 1 Mod 0 eyeballs, about the finest one can get is 50 RPM and 0.5 MPH. Parallax seems not to be problem as the instrument needles are very close to the scale. Fifth gear and relatively cool (wet), stock, 175/55 rear tires at 36psi.

**N.B. A re-graphing using a 10th irrefutable data point (0 RPM = 0 MPH) makes 4k RPM to be 84 MPH, all else remains the same.

[Allargando DiFortissimo]

Thanks guys,

That's just what I wanted to know. BTW: The link that John H gave a few messages back also had what I wanted and, oddly enough, I'd already seen that post because I'd copied FredVon4's gear ratio chart into a text file in my smartcar folder. Don't know how I missed it, but it appears I didn't read far enough in, stopping after the gear ratio chart.

Oh well, it's the first mistake I've ever made (in 55 years), so while I hate to mess up my record, I'm reckon I'm still not doing too badly.

Thanks again,

ADiF (who has another question but is afraid to ask it)