Getting mixed responses about RPM

[brzninja]

Hello! I've been trying to find what the rpm is when going 60-70 mph. I've been getting answers anywhere from 2500 to 3700 and I don't know which is true.

If an owner can clarify this for me that would be amazing!

Thanks!

[Synack]

Depends on what gear you are in...........

[pyro530]

Originally Posted by Synacks

Depends on what gear you are in...........

And what transmission you have.
I'm usually around 3k at freeway speeds, say 65mph

[ZENBOX]

In my BRZ when I'm cruising at 70mph in 6th gear, my rpm is right at 3K. Hope that helps.

[Draco-REX]

Manual transmissions are around 3K. Auto transmissions will be around 2.5K due to higher gearing.

[brzninja]

Originally Posted by Synacks

Depends on what gear you are in...........

Sorry, I forgot to mention cruising at top gear.

Thanks for everyone's responses, I greatly appreciate it.

[Synack]

Originally Posted by Draco-REX

Manual transmissions are around 3K. Auto transmissions will be around 2.5K due to higher gearing.

That's probably why they claim a higher MPG.

[Dadhawk]

Originally Posted by brzninja

Hello! I've been trying to find what the rpm is when going 60-70 mph. I've been getting answers anywhere from 2500 to 3700 and I don't know which is true.

If an owner can clarify this for me that would be amazing!

Thanks!

Here's mine at 55/60/70MPH. The MT would be higher.

[azian_advanced]

This should help.

Note: P = Premium; L=Limited; AT=Auto; MT=Manual; FD2=4.1 Final Drive; FD1=3.727 Final Drive - No LSD (JDM-Only)

chart in MPH

Here it the same graph in kilometers per hour: link

Also, here it is for the FR-S: MPH KPH


Note: the BRZ Premium data is based on 16" tires for the japanese market, the North American market premium comes with 17" which is the same as the BRZ Limited version.

[DSPographer]

Originally Posted by azian_advanced

This should help.
OEM tire sizes (tire deflection due to vertical load neglected), OEM wheel sizes, final drive ratios, transmission gear ratios are all factored in on these charts.

I don't understand why so many posts use the wrong tire rolling circumference when taking the trouble to make a chart like this. You cannot just use the wheel size and nominal profile times tire width to calculate the rotations per mile of a tire: it simply doesn't work. But, you don't need to: the tire manufacturers standardize the rolling circumference so that speedometers will work. Just visit tirerack.com or Michelin's website and you can find out the correct rotations per mile for the various tire sizes. The value for 215/45R17 tires is 844 revolutions per mile. The correct chart for the MT limited should therefore show 59.0 MPH for 2nd gear at fuel cutoff of 7450 RPM.

60*7450/4.1/844 ./[3.626 2.188 1.541 1.213 1 .767]
ans =
35.6249 59.0383 83.8260 106.4928 129.1758 168.4170

Note that car speedometer displays are not necessarily exact. I once worked at a factory that made tachometers, gauges and speedometers for Ford and Chrysler. The speedometer settings were set to read about 1 MPH high at 60 MPH on average. I understood that the logic was that it was best to err slightly on the side of the driver thinking he was going faster than he really was to avoid arguments about causing speeding tickets etc.

[Synack]

Ouch, no wonder the FR-S Auto is slow. Look at the graph. The auto 4th gear is the same as the MT 5th. They did the Manual perfect for gearing on the FR-S, I really like it.

[Synack]

So does this mean dynos are done in 5th gear MT and 4th gear AT?

[SkullWorks]

please take down that graphic or fix it,

that is so far off it hurts to look at...

[brzninja]

Originally Posted by Dadhawk

Here's mine at 55/60/70MPH. The MT would be higher.

Exactly what I was looking for. Thank you!