Re: A hardworking SA50 needs some speed but must maintain to
Posted: Tue Jun 23, 2015 6:27 pm
Stock runs about 37 mph.
Adding 9:1 gears, a Polini Variator, and a 90/90 get 49 according to Wheelman's experience. (math says 57, insufficient power to realize potential)
Adding just the Polini Variator and a 90/90 get 42 according to Wheelman's experience. (math says 42)
Adding just the 9.8:1 gears and a 90/90 get 44. (math says 44)
With that info we can determine what the Polini is actually doing and what it's worth in RPM and MPH.
Stock = 7,574.97 RPM at 35 mph and 12,985.67 revs per mile @ highest ratio possible from the CVT (.85)
and 35.25 mph @ 7,631.22 rpm with a 90/90
9.8:1 = 5,981.63 RPM at 35 mph and 10,254.23 revs per mile with a 90/90
and 44.65 mph @ 7,631.22 rpm with a 90/90
9.0:1 = 5,493.33 RPM at 35 mph and 9,417.15 revs per mile with a 90/90
and 48.62 mph @ 7,631.22 rpm with a 90/90
So if a Polini and a 90/90 gets us 42 mph at ~7,631.22 we can calculate what gearing benefits it offers.
42 mph = 2,661,120 inches per hour/ 51.45 inches per tire revolution = 51,722.45 tire rovolutions per hour
51,722.45 tire rev per hour/ 60 = 862.04 tire rpm x 12.12 final reduction = 10,447.934 engine rpm
10,447.934 rpm x .85 stock overdrive = 8,880.7445 engine rpm in stock form
7,631.22 stock except 90/90 peak / 8,880.7445 @ 42 mph = .859 additional overdrive of Polini
So a Polini Variator based on Wheelman's results provides an additional ~14.1% overdrive over stock. Direct is 1:1, stock gets to about .85:1 and the Polini gets to about .723:1.
So a Polini with its .723:1 and 9.8:1 and a 90/90 should be good for 8,722.12 revs per mile and 52.49 mph @ 7,631.22 (same RPM as 35 mph stock except 90/90)
Adding 9:1 gears, a Polini Variator, and a 90/90 get 49 according to Wheelman's experience. (math says 57, insufficient power to realize potential)
Adding just the Polini Variator and a 90/90 get 42 according to Wheelman's experience. (math says 42)
Adding just the 9.8:1 gears and a 90/90 get 44. (math says 44)
With that info we can determine what the Polini is actually doing and what it's worth in RPM and MPH.
Stock = 7,574.97 RPM at 35 mph and 12,985.67 revs per mile @ highest ratio possible from the CVT (.85)
and 35.25 mph @ 7,631.22 rpm with a 90/90
9.8:1 = 5,981.63 RPM at 35 mph and 10,254.23 revs per mile with a 90/90
and 44.65 mph @ 7,631.22 rpm with a 90/90
9.0:1 = 5,493.33 RPM at 35 mph and 9,417.15 revs per mile with a 90/90
and 48.62 mph @ 7,631.22 rpm with a 90/90
So if a Polini and a 90/90 gets us 42 mph at ~7,631.22 we can calculate what gearing benefits it offers.
42 mph = 2,661,120 inches per hour/ 51.45 inches per tire revolution = 51,722.45 tire rovolutions per hour
51,722.45 tire rev per hour/ 60 = 862.04 tire rpm x 12.12 final reduction = 10,447.934 engine rpm
10,447.934 rpm x .85 stock overdrive = 8,880.7445 engine rpm in stock form
7,631.22 stock except 90/90 peak / 8,880.7445 @ 42 mph = .859 additional overdrive of Polini
So a Polini Variator based on Wheelman's results provides an additional ~14.1% overdrive over stock. Direct is 1:1, stock gets to about .85:1 and the Polini gets to about .723:1.
So a Polini with its .723:1 and 9.8:1 and a 90/90 should be good for 8,722.12 revs per mile and 52.49 mph @ 7,631.22 (same RPM as 35 mph stock except 90/90)

