Gear Ratios : Speeds In Gears : When To Shift a Skyline GT-R

This post is all math. If you don’t have some math, to fill into the blanks, you can’t figure any of this out.  What you need to know:

• Tire Height – can be calculated from
• Width
• Aspect ratio
• Wheel size
• https://spicerparts.com/calculators/tire-height-calculator
• Transmission in the car
• Is it stock?
• Is it modified?
• 5 speed
• 6 speed
• Overall Gear ratio
• 4.111 is stock R32/R33 GT-R
• 3.545 is stock R34 GT-R
• It can be something else
• Shift Point
• If you shift with the stock tach you are shifting at 7600 rpm
• If you shift at the limiter then that is most likely 8000 rpm
• If you shift at a different point, the links are below to figure that out

One example, the bluecar.  It has a 275/35/18 tire on it, which is 25.58 inches tall. It has a stock 5 speed transmission. Overall/Final gear ratios are 4.111. It is shifted at 8500 rpm. 

So you can see that by shifting at a higher RPM, you fall into a bit better point on the dyno chart for this car, and this turbo combination.  https://www.gtrusablog.com/2019/10/finally-running-bluecar-on-dyno-results.html

So about if we swapped to a Getrag? Well actually the bluecar used to have a Getrag in it, but we sold it to a friend, that needed one.  So add a 6th gear, keep the 4.111 gear vs the 3.545 gear of the R34. Then we get:

Now onto a sequential.  The Nismo has(had, till I stole it out for Big Bird 2) OS88 sequential transmission, and 4.375 gears.  255/50/16 tires are 26.04″ tall. The shift points are higher at 9000 rpm, as this car has a lot of cam in it. The OS ratios are:

• Nissan Skyline GT-R transmissions
• Getrag 6 speed transmission parts
• How to install a 6 speed transmission
• What fluid should I use in my transmission?
• FS5R30A
• V160

Buy USA Legal R32 and R33 Skylines at Importavehicle.com!
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