Currently banned from the garage, so it's all bench racing for now. Someone mentioned their speed in 5th with a J160 and 8k redline on little 235/45R13 tyres with 545mm tyres, so naturally I had to check and it was indeed just over 200kph. Which got me thinking about the ute and the KP, so I'll dump the KP calcs here for future reference:
J160 ratios from interwebs
- First Gear: 3.874
- Second Gear: 2.175
- Third Gear: 1.484
- Fourth Gear: 1.223
- Fifth Gear: 1.000
- Sixth Gear: 0.869
Likely diff ratios, 3.909, 3.916, 4.083 and 4.10, which I'm going to call 3.909 and 4.100 for the sake of boredom. I'll through 4.444 in for fun, too.
Tyre size is highly likely to be 195/50R15 which according to earlier posts is 22.7 inches and according to a calculator, 576.580mm.
No, wait, checking R888 specs as that's what I'll probably run, and the US site says 22.6 inches which calcs to 574.040mm and the UK site says 572mm. 22.5 yields 571.5 so I'm going to assume that it's 572.499 which I'll round up to 572.5 for ease :-p
The general formula is simply (((PI * TyreDiameter * MaxRPM * 60MinutesInAnHour) / 1000000MillimetersInAkilometer) / DiffRatio) / GearRatio
Which for this car is just (((PI * 572.5 * 8000 * 60) / 1000000) / DiffRatio) / GearRatio
3.9 option
And for this ratio is (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / GearRatio
- First Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / 3.874 = 57.0
- Second Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / 2.175 = 101.5
- Third Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / 1.484 = 148.8
- Fourth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / 1.223 = 180.6
- Fifth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / 1.000 = 220.9
- Sixth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 3.909) / 0.869 = 254.1
Cruising in top/6th:
- 100/254.1 * 8000 = 3148 RPM
- 110/254.1 * 8000 = 3463 RPM
- 120/254.1 * 8000 = 3778 RPM
4.1 option
And for this ratio is (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / GearRatio
- First Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / 3.874 = 54.4
- Second Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / 2.175 = 96.8
- Third Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / 1.484 = 141.9
- Fourth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / 1.223 = 172.2
- Fifth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / 1.000 = 210.6
- Sixth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.100) / 0.869 = 242.3
Cruising in top/6th:
- 100/242.3 * 8000 = 3301 RPM
- 110/242.3 * 8000 = 3631 RPM
- 120/242.3 * 8000 = 3962 RPM
4.3 option
EDIT: Added this ratio.
And for this ratio is (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / GearRatio
- First Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / 3.874 = 51.8
- Second Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / 2.175 = 92.3
- Third Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / 1.484 = 135.3
- Fourth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / 1.223 = 164.2
- Fifth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / 1.000 = 200.8
- Sixth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.300) / 0.869 = 231.0
Cruising in top/6th:
- 100/231.0 * 8000 = 3463 RPM
- 110/231.0 * 8000 = 3809 RPM
- 120/ * 8000 = 4155 RPM
4.4 option
And for this ratio is (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / GearRatio
- First Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / 3.874 = 50.1
- Second Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / 2.175 = 89.3
- Third Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / 1.484 = 130.9
- Fourth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / 1.223 = 158.8
- Fifth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / 1.000 = 194.3
- Sixth Gear: (((PI * 572.5 * 8000 * 60) / 1000000) / 4.444) / 0.869 = 223.5
Cruising in top/6th:
- 100/223.5 * 8000 = 3579 RPM
- 110/223.5 * 8000 = 3937 RPM
- 120/223.5 * 8000 = 4295 RPM
Drag vs Circuit vs Street
According to a calculator mid 12s and 180kph at the end of a strip. According to others results 13.8 @ 160kph
That might make the 3.9 the best due to the lack of need to shift out of fourth and thus only 3 shift dead times.
If it's a bit slower, 4.1 would be better. But what if I build a higher capacity engine with hotter than stock cams later?
It'd depend on which circuit, but I imagine I'd be up against the limiter in sixth with the 4.4 on any reasonable straight.
Street, motorway pulls are fun :-p But so is cruising, how about cruise RPM at 100, 110, 120 in each? DONE, 3.9 wins.
Creeping in 1st at low speed is fun. I'll add a line to each diff ratio for that... No, no I won't. Div 10 for 800 idle.
So the range of first gear creeping is 5kph to 6kph (of course), and all are fine.
In summary, 4.4 ruled out, strongly favouring 3.9. Interesting, as I'd not thought about this for this car, yet.
Similarly interesting, with the FD box in the ute, 3.9 is my ratio of choice, too. but a much higher top speed with larger tyre diameter and taller top.
Special Thanks
Piimae for his inspiration, and distraction, me for my failure to focus on what matters right now. #FAIL.