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I used to launch Andrew's 230rwkw CA18DET 1200 in 2nd gear with 4.375 diff gears. Even on uphill start-lines:
http://www.youtube.com/watch?v=gU1HTj8-p-g

I've got a 4.3 LSD hilux diff behind a reasonably worked CA (330rwhp last time on the dyno).
I'm now moving into circuit racing with a restrictor and will need to go a taller ratio to compensate for the reduced rev range I get.

I use to drag race my coupe in the above mentioned setup and was crossing the line needing to shift into 5th gear just before the 1/4 mile mark at around the 190kph mark. I felt at the time my 60ft time was suffering because of the shorter diff ratio (4.3), whilst great to get a naturally aspirated car off the line, with a turbo setup it didn't really allow the car to build boost quickly enough. It was my feeling that given how light the car was, there was insufficient load put on the engine from a standing start, therefore it actually build boost slower and flow on effect was a slower 60ft time. Not to mention as indicated by others, 4k @100kph gets annoying pretty quickly. I will be rebuilding mine with a 3.5 (or taller if I can find one) but without the restrictor would go for a 3.7-3.9.

hmm, well considering i dont do much freeway really i'm thinking the 4.3 might be the go

even with the 4.1 i was debating if second was a better gear to take off with, i suppose with the 4.3 and a small turbo second gear launch is probably best, though a bit more lag with a turbo upgrade may ruin that idea

i've used 4.9s a bit, in the rally car mainly, its a bit different with the ol A14, but a bit of high reving freeway action isnt too bad if ya dont care about fuel consumption

downloaded a calculator spreadsheet and put in all the variables, it was putting top speed at around 200 at 7000rpm, sounds like lots more than i need

so i write that sounding like 4.3 is the go, but still unsure, 4.3 is definitely most convenient for me, but swapping a torsen between centres at a later date is not so convenient

I started off with a 4.3

Good Point - Awesome acceleration off the line, Was great fun to drive around towm and off at the lights

BAD Point - Would run out of legs on the quarter mile and rev its box off at 100 kph on the freeway. Almost 4000 rpm with the size tyres I had.

I now have a 3.8 ratio, which means the car is more drivable and 3000 rpm at 100kph. Which is why I went for this option. At the end of the day it is still a reasonably quick car and besides the 4.3 diff use to piss me off majorly on HWY runs at 110 or 120 kph

how does it feel? too short/long?

for comparison leigh (lags) used to run 4.3 in the old wagon with the hilux diff that i now have...

I have 4.33 with mine and 1st is pretty useless most of the time. I'll be looking for 3.9 if and when I rebuild. I have 205/40/16 tyres and sit almost right on 3000rpm at 100km/h in 5th so top speed of 220kmh is probably the maximum possible mathematically. Iv'e never gotten close enough to find out.

I run 3.54 at the moment. I can use 1st gear, but it's boring. 3.7 to 3.9 is still the best I reckon.

gday guys, am embarking on some research for diff ratios

I think i have a 4.11 in the car (H190) but i have a 4.375 as a spare. I have a Topgear Torsen which i was going to put in the spare, but just wondering what diff ratios people have found good in their CADET 1200s?

Standard S13 CADET manual uses 4.363 ratio, though would be a different tyre circumfrence to my/most 1200s

Car purpose is a weekender, but prob do some track days... what sort of top speed people get on tracks? (phillip island?)