maybemark Posted March 16, 2012 Share Posted March 16, 2012 I have 2 r-200 rear ends. One is a 354 and the other is a 390. i was wondering if anyone knew which one i should put on my car. My car will be a daily driver, but, it has 440 injectors and a holset turbo on it, another words, i want to take it to the track. Any feed back would be appreciated thanks Mark Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 16, 2012 Share Posted March 16, 2012 (edited) If you use tiny tires with the 3.54 you can get the same overall ratio as with the 3.9. Edit - actually, they don't have to be tiny. There's not a ton of difference between them. 3.54 - higher top speed, 3.9 - quicker (more acceleration from a stop). Edited March 16, 2012 by NewZed Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted March 16, 2012 Share Posted March 16, 2012 (edited) It is a trade-off. You will love your 3.90 at the track and you will hate it on the highway. I have 3.90 gears with 400lbs of torque. So, I don't use 1st gear-it is useless, now; but I really like the 3.90 with my L6 and used 1st gear all the time. I built my car to drag and autocross. If you do very much commuting for your daily driver, I'd go 3.54. I felt so wastefull using those low gears on the highway. If you really race your car a lot, go 3.90. If you make a special plate for your jack and you modify your exhaust to be easy to remove under the diff, removing and replacing the diff isn't a huge job, so you could just swap back and forth depending on what you are doing more of for the season. If your motor makes a lot of torque, I'd go with the 3.54. If it makes weak torque (like a stock L6) or if you need lots of rpms for your turbo, I'd go with the 3.90. You will be really winding at highway speeds, which kind of hurts your fuel efficiency. Edited March 16, 2012 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
maybemark Posted March 16, 2012 Author Share Posted March 16, 2012 (edited) thanks guys I am still not sure what i want to do. The car is mostly for street, but, having 440 injectors and a holset hy35 in there, i have 16" tires on it. Plus it is all working off of megasquirt, not the stock ECU. Plus i have 3" pipe out of the turbo all the way back to the tail peice. This car is far from stock. i am understanding, that the 354 will give me better gas milage, and the 390 is better for the track. I guess the better gas milage wins. I will only be taking to the track a few times a season. Thanks again Mark anymore comments are appreciated Edited March 16, 2012 by maybemark Quote Link to comment Share on other sites More sharing options...
Leon Posted March 16, 2012 Share Posted March 16, 2012 Like NewZed said, the difference between a 3.54 and 3.9 is small. I doubt fuel mileage would change much, if at all, and your top speed is limited by aerodynamics, not gearing. You'll be fine with either, but I'd probably opt for a 3.54 if you have a torquey turbo. I'd save the 3.9 for something a bit more tightly wound. Here is a great site to compare gearing, numbers and a nice chart: http://webspace.webring.com/people/cz/z_design_studio/ Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted March 16, 2012 Share Posted March 16, 2012 If by "track" you mean the dragstrip, you will get more use out of a 3.54. I've run both, and with the 3.90 I get no boost in 1st and have to shift to 5th before the end of the 1/4. The 3.54 fixed both those issues and I run a faster 60' and ET as a result. On a road track, it probably won't make too much difference, but the higher ratio may keep you in the power band better than the lower. Unlikely you will need your top speed unless you have more than a 1/4 mile straight. Quote Link to comment Share on other sites More sharing options...
calvin280zxt Posted March 16, 2012 Share Posted March 16, 2012 Id have to agree aswell. I was going to put my 3.90 in but theres a reason the turbos came with 3.54. Mine is stock setup running 10psi and i still rip through 1st barely getting full boost Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 16, 2012 Share Posted March 16, 2012 You guys ever consider launching in 2nd? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted March 16, 2012 Share Posted March 16, 2012 You guys ever consider launching in 2nd? Not with a 3.54 and the T5. With the 3.90, it would difficult without bogging, and that 5th gear shift right before the traps is a tough one. Quote Link to comment Share on other sites More sharing options...
maybemark Posted March 16, 2012 Author Share Posted March 16, 2012 Hi guys thanks for all your input, when i said track, i mean't the 1/4 mile drag. I never thought of launching in 2nd, with the 390, i imagine the turbo would like that, alot of strain on the motor. I am hoping to have boost of about 18 lbs. But still all and all, I think the 354 would be best Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 17, 2012 Share Posted March 17, 2012 Whether you have a 4 or a 5 speed matters also. The 3.9 typically came with the 5 speeds, the 3.54 typically had a 4 speed or automatic. Quote Link to comment Share on other sites More sharing options...
calvin280zxt Posted March 17, 2012 Share Posted March 17, 2012 240Z 70-73 MT (3.364) (R180) 240Z 70-73 MT 5spd. (3.900) (R180) - non US 240Z 71-73 Auto (3.545) (R180) 260Z 74 MT (3.364) (R180) 260Z 74 Auto (3.545) (R180) 280Z 75-76 (3.545) (R200) 280Z 77-78 MT (3.545) (R200) 280Z 77-78 Auto (3.545) (R180) 280ZX 79 MT,4 Spd,2 Seater (3.364) (R180) 280ZX 79 MT,5 Spd,2 Seater (3.364) (R180) 280ZX 79 All With Automatic(3.545) (R180) 280ZX 79 MT,4 Spd,4 Seater (3.364) (R200) 280ZX 79 MT,5 Spd,4 Seater (3.7) (R200) 280ZX-GL 79 (3.7) (R200) 280ZX 80 MT,2 Seater (3.545) (R180) 280ZX 80 Automatic 2/4Seat (3.545) (R180) 280ZX 80 MT,4 Seater (3.9) (R200) 280ZX-GL 80 (3.9) (R200) 280ZX 81-83 Automatic all (3.545) (R180) 280ZX 81-83 Turbo - all (3.545) (R200) 280ZX 81-83 MT (3.9) (R200) - - - - 300ZX's - - - - - -- - 300ZX 84-86 MT and A/T (3.7) (R200) 300ZX 84-86 Turbo MT and A/T (3.54) (R200) 300ZX 87-89 MT and A/T (3.9 ) (R200) 300ZX 87-89 MT and A/T (3.9 ) (R200) 300ZX 87-89 Turbo MT and A/T (3.7 ) (R200) Note Turbos: #1) after 4/87 only-(3.7 Clutch Type LSD) 2) 88 All White SS used a 3.7 Viscous Coupling LSD) 3) LSD Unites Came With Finned Rear Covers Quote Link to comment Share on other sites More sharing options...
maybemark Posted March 17, 2012 Author Share Posted March 17, 2012 calvin did the 82 280zx manual, come with the R180? I had 2 cars that i made into one, Both 2+2's 82,c 280zx I took the NA body, which had a manual trans, and replaced the motor from an 82 turbo automatic. I am wondering now, if I have the R180 in there now. If this is the case, should i go with the R-200 390? Quote Link to comment Share on other sites More sharing options...
calvin280zxt Posted March 17, 2012 Share Posted March 17, 2012 (edited) The na body should have an r200 3.90 in it. I have those 2 exact cars and car verify they are both r200 as i changed the input flange from one to the other in my tranny swap Edited March 17, 2012 by calvin280zxt Quote Link to comment Share on other sites More sharing options...
maybemark Posted March 17, 2012 Author Share Posted March 17, 2012 calvin thanks Mark Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 17, 2012 Share Posted March 17, 2012 Whether you have a 4 or a 5 speed matters also. The 3.9 typically came with the 5 speeds, the 3.54 typically had a 4 speed or automatic. Should have mentioned also, that the 5 speed the 3.9 came with had a 3.062 first gear ratio in the ZXs. The 4 and 5 speeds that the 280Z with a 3.54 came with had a 3.321 first gear. So it also matters which 5 speed that you have. Lots of possible combinations out there. Quote Link to comment Share on other sites More sharing options...
maybemark Posted March 17, 2012 Author Share Posted March 17, 2012 I have the 5 speed 280zx turbo, but this turbo had an automatic with it, I just used the engine, and put it in another car that was an NA 280zx manual 5 speed Quote Link to comment Share on other sites More sharing options...
calvin280zxt Posted March 17, 2012 Share Posted March 17, 2012 (edited) So you should have a 3.062 1st gear 5 pseed and a 3.90 currently. Id probaly just stick with that unless you feel your over reving on the highway or 1st gear is useless under high throttle Edited March 17, 2012 by calvin280zxt Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 17, 2012 Share Posted March 17, 2012 The 79 ZXs had the older 5 speed, with the 3.321 first gear. Probably why they came with the 3.364 or the 3.7 rear, but not the 3.9. Just to confuse things even more. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 17, 2012 Share Posted March 17, 2012 Either way, I'd go with the 3.54. I've run the 3.70 with the late ZX 5 speed and it isn't too tall for a NA car. I have the feeling your turbo would like it a lot. Quote Link to comment Share on other sites More sharing options...
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