Vx Rpm

[jmf]

What rpm are other people getting at 60mph with there vx? i think my tach is going, some days its different than others. i was wondering what was a good baseline to compare.

thanks
justin

[vxdude]

I can go 66mph at 2000rpm, so i say im at 1700-1800rpm

[GasSavers_TomO]

tire size is a huge variable in that equation.

Posters should state their current tire size when they respond.

Clutch condition is another factor, a slipping clutch can throw off the tach.

On that note:
155/80/13
Clutch on the way out (it slips into fourth and fifth at RPMS above 3K)
65MPH is 2200RPM
60MPH is 2050RPM

[IndyFetch]

I'm at about 2450 RPM at 75 mph, so it should be at around 1960 RPM at 60 mph.

'95 VX, tire size 175/70R13.

[GasSavers_NovaResource]

Originally Posted by TomO

tire size is a huge variable in that equation.

It shouldn't. MPH (on the speedometer) is based off the gears in the transmission. Changing tires will cause your car to physically go faster or slower than 60 but the spedometer will still display 60-mph.

So my question is, how are you determining your speed? By the speedometer or by an externel measuring device like a GPS?

[IndyFetch]

Originally Posted by NovaResource

It shouldn't. MPH (on the speedometer) is based off the gears in the transmission. Changing tires will cause your car to physically go faster or slower than 60 but the spedometer will still display 60-mph.

So my question is, how are you determining your speed? By the speedometer or by an externel measuring device like a GPS?

I'm measuring based on the speedo. I should have mentioned that.

[R.I.D.E.]

My VX with the original tires was on the threshold of loosing lean burn at just under 75 MPH and 2500 RPM. The odometer was off by -1% based on 50 miles. When I changed the tires it was off by +2%. Michelin X 175x70x13. The new tires killed my mileage, costing me about 10% average.

That was when the car had 40K original miles.

OP didn't ask for indicated speed .

Wacky tach could possibly be an indication of ignition issues.

regards
gary

[GasSavers_NovaResource]

A 1% error is the norm for factory speedometers and odometers with factory tires

Did you calculate your mileage based on the odometer or the actual miles traveled? For example, if you went to larger (taller) tires, your speedometer and odometer will be incorrect. At a displayed 60-mph you are actually traveling slightly faster (maybe 62.5-mph). And if you travel 62.5 miles, the odometer will only show 60 miles. So if you changed your tire size, you have to correct the mileage shown on the odometer to get an accurate MPG reading.

For example, if your original tires are 215/65-15 (26.0" tall) and you switch to thinner and slightly taller 195/75-15 tires (26.5" tall). That would create a 2% error in the speedometer and odometer. At a displayed 60-mph, the car will actually be traveling 61.6-mph. At a displayed 300 mile trip you would have actually traveled 306 miles.

Let?s assume you used 8.5 gallons for that trip. If you used the incorrect 300 miles you get a fuel economy of 35.29. If you use the correct 306 miles you get a fuel economy of 36.