Gearing and diff choice

[Snapfrozen]

Happy new year everyone. I'm trying to decide what diff to go to and ultimately if I change my gearbox as well.

Car will end up with approx 200whp or a tad more. Assume for the sake of this argument that it will be able to reach its top speed on pukekohe, Hampton and taupo


using 7000 as the redline, the 6 speed box with either the 3.9 or 4.1 or 4.3 diff gives you a top speed of 212 (4.3) and 223 (4.1) and 234 (3.9)
using 7000 as the redline, the 5 speed box with either the 3.9 or 4.1 or 4.3 diff gives you a top speed of 220 (4.3) and 231 (4.1) and 243 (3.9)

So by my maths, from what I've read and general internet reading, the 6 speed with a 3.9 torsen is my best bet. Good ratios, no drifting so torsen is fine, stronger box and strongest factory diff, easish to get hold of.

Any feedback or advice regarding my idea or real world use?

[WideOpenThrottle]

Keith Jones was doing 250kph with a Quaife 5 speed box and 4.1 diff with his 230-odd hp car from memory.

Personally i prefer the 5 speed as the 6 speed gets you lost as to which gear you are in...but then again if you are driving one all the time then it shouldn't be an issue!?

[Keith Jones]

I wish it had been 250kph Gary!!!
With the Quaife box (0.794:1 5th gear), 4.1:1 diff and 235bhp I was doing around 235kph at the end of the Puke straight. That was around 7000rpm from memory. I doubt that you would be able to get to 7000 with 200 bhp and 3.9.
Top speed at Hampton and Taupo was slower than the old Puke track. With the new track layout Puke will probably be the same as Taupo, possibly a bit slower.

[Furai]

Im running 4.1 and 5-Speed, is great on the motorway but a little much for the poor 1600. In saying that for Gymkhana 2nd gets you going(Just) while first for figure 8s and such has proven to be effective.

I dont think the 6-speed would hugely benefit you, but then again depends on track and how much torque your going to have(Plus where it is in the power band). Im only keen for 6-Speed for Drifting/ lack of power.

Also you can change that gearing slightly with tyres, thats what I did for Drifting. The 185/60s with 4.1 I couldnt get 2nd to spin up, so I put what was equal to a 4.3 ratio tyre(Smaller) and it was great. But also changing tyres all the time is a pain, finding smaller is hard but bigger is easier.

[Snapfrozen]

I wish it had been 250kph Gary!!!
With the Quaife box (0.794:1 5th gear), 4.1:1 diff and 235bhp I was doing around 235kph at the end of the Puke straight. That was around 7000rpm from memory. I doubt that you would be able to get to 7000 with 200 bhp and 3.9.
Top speed at Hampton and Taupo was slower than the old Puke track. With the new track layout Puke will probably be the same as Taupo, possibly a bit slower.

They're maintaining the old back straight, just the choice of whoever is running the day to cone the old track or new track and leave it as run off. I'll eventually reach approx 300whp but that's a long way away and will be turbo v3 for me.

[WideOpenThrottle]

Hi Keith.... if i can get to 220kph on my speedo with my set-up on a track someday then i will be more than happy seeing as you reached 235kph & not 250kph as i thought!