kyle Posted January 31, 2007 Share Posted January 31, 2007 Hi guys- I have recently acquired a Torsen for my 240Z (thanks Katman!). I have two R200's, a 3.54 and a 3.90. Transmission is a 79 ZX five speed (wide ratio). The 3.54 is currently installed, and includes one track day at Thunderhill. I also drive the car to and from track events, so freeway RPM is worth considering. But the car is NOT street driven with any regularity. As it stands, the car has a 9.5:1 L28+1mm, 260/460 cam, SUs, etc. Pretty hot by my standards, but pretty tame by hyridz standards. Freeway RPM is a relaxed 2500, and 1st gear is a lagfest, especially with the lightweight flywheel. Suspension, tire, and brake upgrades are in the works this track season. A turbo is up next year or the year after. I'm torn on which ratio to build the Torsen into. On the one hand, since it's a track car, I ought to gear it as low as possible without topping out. (3.54 = 183 mph! ) Getting the car in a sweet spot for a particular track is probably pointless, as my ability and the car's capability are bound to increase. The possible (eventual?) turbo suggests the higher wider gear ratios would be a wiser choice. And the low low freeway RPM makes for much more pleasant journeys to track day.... but then again, by the time I top out second gear, I'm begging for a ticket. What would you do? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 31, 2007 Share Posted January 31, 2007 I have a 3.54:1 R180 in my car at the moment. To be honest I had to double check that it was a 3.54 as it revs up AWFULLY fast once on boost. If you are doing more than 166mph (top speed with 3.9 according to your 183mph with 3.54), around a track you're doing pretty damn well. I'd go with the 3.9. Dave Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted January 31, 2007 Share Posted January 31, 2007 Yeah... 166 MPH top end is plenty to brag about. Our old Z's aren't very stable at that speed anyway. I'd install the lower gears. Quote Link to comment Share on other sites More sharing options...
kyle Posted January 31, 2007 Author Share Posted January 31, 2007 Thanks fellas. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted February 1, 2007 Share Posted February 1, 2007 Another vote here for the 3:90. Thats what I run in my 280z and I'll top out around 140 mph..roughly. It gets a little scarry after 125 anyway, and floats a bit, so I hardly ever push past that. I'm runnung a little hotter cam in mine (280/510) and have a 240sx (KA) 5 speed.. I don't know how this compares to your zx gear box.. I think my 1st and 2nd gears are diffrent. Quote Link to comment Share on other sites More sharing options...
vashonz Posted February 1, 2007 Share Posted February 1, 2007 The 3.9 instead of the 3.54 makes your gears into a closer ratio transmission. More shifting, but keeps it in the power band easier. Quote Link to comment Share on other sites More sharing options...
kyle Posted February 1, 2007 Author Share Posted February 1, 2007 The 3.9 instead of the 3.54 makes your gears into a closer ratio transmission. More shifting, but keeps it in the power band easier. That (along with lower freeway RPM) is what had me undecided: The engine has a pretty broad powerband (good power from 2500, great power from 3500-7500). Adding a turbo will only broaden it further. I didn't find myself wishing for closer gears, with the exception of 1st, which is useless on a track anyway. One upside to using the 3.90 is I can keep the car operational until the diff is built and ready to go in. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.