Guest 1SickZ Posted October 30, 2003 Share Posted October 30, 2003 whats the best rear end ratio for a turbocharged car that sees the track and highway runs.. 3.5 3.7 4.11 Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted October 30, 2003 Share Posted October 30, 2003 The 3:7 would and is my choice... a 4:11 gets this in my opinion... Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 30, 2003 Share Posted October 30, 2003 All indications from 3 years of posts here lead me to say the 3.54:1 is the way to go... I'm running a 3.36:1 right now and would like a bit more 1st gear/off boost torque, so I am swapping to a 3.54:1. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 30, 2003 Share Posted October 30, 2003 I agree with the above responses assuming you are using an L28ET. A turbo V8 like a SBC 350 would probably put a 3.54 to good use as well, but an RB or an SR20 motor (much higher revving) would be better off with the 3.90 or 4.11, or even higher. Quote Link to comment Share on other sites More sharing options...
DavD3 Posted October 31, 2003 Share Posted October 31, 2003 Are we talking about the same differentials? Because if 3.7 would be LSD vs. 3.5 open i think LSd will get better traction. Am i correct ??? David Quote Link to comment Share on other sites More sharing options...
Wagz Posted October 31, 2003 Share Posted October 31, 2003 David - An LSD will definitely get you better traction, but 3.7's aren't necessarily always LSDs. 3.7 ratios are available in open diffs too. Drax - Are you going to do a complete diff swap or just a gear swap? I'd be interested in your 3.36 if/when you do it. It'd be a good match to my T56 tranny.... Quote Link to comment Share on other sites More sharing options...
Guest Cusp Posted October 31, 2003 Share Posted October 31, 2003 Sure, the LSD would be better, but I think he means all things equal, which gear ratio is best. What I would do is use the 81-83 5 speed tranny with the lower gearing but the good overdrive. Then the 3.9 or 4.11 isn't bad, and finding an LSD in those gearings is easier. I just hope you have an s30 or this advice won't help. What model Z is it? Quote Link to comment Share on other sites More sharing options...
Guest 1SickZ Posted October 31, 2003 Share Posted October 31, 2003 its an 86 Turbo Z i had in it a open 3.7 last ngiht went 12.4 @ 119 and on second run i shredded the diff gears... so now i need somthing new.. i know somone selling a 4.11 lsd diff and might have my luck with a 3.7 lsd putting in a 3.5 open for now but curious which is reccomended i dont want to lose anymore top end then i have but would love to gain some more mph in the 1/4.... im using an 88 SS nissan tranny instead of the t-5. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted October 31, 2003 Share Posted October 31, 2003 If you dont' have to shift 5th with 4.11, you might be able to get it to work with tall tires. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 31, 2003 Share Posted October 31, 2003 IMHO, the VG motor will be better off with a 3.54. Quote Link to comment Share on other sites More sharing options...
Guest 1SickZ Posted October 31, 2003 Share Posted October 31, 2003 not arguing your opinion... but could you please explain why.. vg likes 3.54.... Thanx Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted October 31, 2003 Share Posted October 31, 2003 A generalization... Turbo motors like load. By having to shift earlier, you have to get out of boost. The longer you can stay in a gear, the longer the turbo can spool. The 3.54 or better yet 3.36 allows that to happen. It is pretty much the opposite of the n/a set-ups where you want to run through the gears quickly. Running through the gears quickly with a turbo set up, does not allow you to take advantage of the turbo. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 31, 2003 Share Posted October 31, 2003 3.36 I have is an R180... but you're welcome to it if you want it! Quote Link to comment Share on other sites More sharing options...
Wagz Posted October 31, 2003 Share Posted October 31, 2003 My bad. I was assuming R200. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted October 31, 2003 Share Posted October 31, 2003 A generalization...Turbo motors like load. By having to shift earlier' date=' you have to get out of boost. The longer you can stay in a gear, the longer the turbo can spool. The 3.54 or better yet 3.36 allows that to happen. It is pretty much the opposite of the n/a set-ups where you want to run through the gears quickly. Running through the gears quickly with a turbo set up, does not allow you to take advantage of the turbo.[/quote'] Then wouldn't say short shifting with a numerically high gear in the back give you the same result, or better yet, just running a trans like a powerglide? Something else to consider is a turbo engine (generally) has lower compression, hence a numerically higher diff gear would help with off boost driveability. If you can buzz it to 7k, I would run a 3.90, or 3.70, but I am not a fan of 4.11. The difference between any of them is probably not much. Also, the heavier your car, might be a little better to go numerically higher as well. I run 3.90's with the T5, and I went faster then with 3.56's. FWIW. Quote Link to comment Share on other sites More sharing options...
Thumper Posted October 31, 2003 Share Posted October 31, 2003 Hey lockjaw you're running the 3.9? Iis that the one out of the n/a car. If so what kind of tires are u running at the track. I just went to the track in my car and had one wheel spin and I ran a 15.8 with a bad valve. And I'm only running 215/70 on stock rim, although I do have a very bad diff mount. I would like to stay with 3.9 when I go turbo but I need lsd so i'm getting the 3.7lsd. Also how much does ur car weigh. Mine weighed 2750 without me 1/4 tank of gas, full radio, interior etc... TIA Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 31, 2003 Share Posted October 31, 2003 I run 3.90's with the T5, and I went faster then with 3.56's. FWIW. I had just the opposite experience. My traps have been consistantly 2-3mph higher this past summer with the 3.54, after replacing the 3.90 in July. Maybe it's the way I drive it. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted November 2, 2003 Share Posted November 2, 2003 I swapped to the 3.54 from 3.36 yesterday, and I am pleased with the results. I think a 3.70 would be just fine too. Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted November 2, 2003 Share Posted November 2, 2003 I'm pretty happy with the 3.7 lsd but I run a 25.3" tall tire and the slicks I have are 26.0". If I ran a shorter tire I would run a 3.54. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 2, 2003 Share Posted November 2, 2003 I ran 25.6 inch tires with 3.90. (Just too lazy to swap it back to 3.54) I think due to the gearing, I run better in 1/8mi than 1/4 mi. 8.60 at 86 mph and 13.3 at 106, so I'm only acceralating 20mph in 660' after 86 mph. Quote Link to comment Share on other sites More sharing options...
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