M4 Manual or Dual Clutch Transmission DCT? Video compare

[CanAutM3]

Originally Posted by bradleyland

Based on the information available on BMW's website, it looks like the DCT has about a 20% shorter ratio in 7th, compared to 6th in the 6MT.

At 80 MPH, you'll have:

6MT: 3237 RPM
DCT: 2552 RPM

At 90 MPH, you'll have:

6MT: 3642 RPM
DCT: 2871 RPM

I used this formula:
rpm = (mph x final gear ratio x 336) / tire diameter inches

Tire diameter is based on 19" wheels with a 26.6" total diameter (manufacturer's spec).

I dropped the figures in to a spreadsheet. If anyone sees any errors, please point them out so I can correct.

https://docs.google.com/spreadsheets...it?usp=sharing

The calculation above is a good approximation, but not an exact calculation. Tires deform as they roll, so it is better to take the "Revs per mile" number for a more accurate calculation.

RPM = mph x gear ratio x FD ratio x (Revs/Mile) / 60

For instance, taking the 26.6" diameter for the 275/35R19 PSS yields 758 revs/mile while the Michelin spec is 783 rev/mile. A 3.3% difference.

[bradleyland]

Originally Posted by CanAutM3

The calculation above is a good approximation, but not an exact calculation. Tires deform as they roll, so it is better to take the "Revs per mile" number for a more accurate calculation.

RPM = mph x gear ratio x FD ratio x (Revs/Mile) / 60

For instance, taking the 26.6" diameter for the 275/35R19 PSS yields 758 revs/mile while the Michelin spec is 783 rev/mile. A 3.3% difference.

Thanks! Updated figures and spreadsheet.

[ujwal1989]

That is amazing info! About 700-800rpm is not too big of a difference then! Thank you bradleyland and CanAutM3!