Whats the best gear for turbo cars.

[smackmybutter535i]

Just curios. At first I had a 3:91 M5 rear, That was way too much. I would just smoke tire. Now I have a 3:73. Someone told me that a higher gear is better for a turbo and I noticed yellow's 2:93. Should I switch from my low gear to a high gear? If so what should I use and why? Does the higher gear improve 0-60 1/4 mile? Why is higher better on turbo applications and not on N/A cars?

[Jeremy]

You need to choose your gearing based on power output and shift points, like always. A longer geared differential like a 2.93 is great when you have lots of power to spare, want to reduce the number of shifts in the 1/4 mile, and get better traction off the line. It's also a very nice high speed cruising gear.

My power output is quite a bit lower than Todd's and I'm very happy with my 3.46. A bit of load is required to get the turbo to spool, so longer gearing helps in that regard too. With a 3.91 diff you'd probably see very little boost in first, and probably not a whole in second, either.

With low to moderate boost levels, stock or near stock is probably best. 3.25 gears are great, as are 3.07 or 3.46. It all depends exactly what you want the car to do. If you're happy with the 3.73, there's no real reason to change it.

Course, throw all that right out the window if you've got an automatic, lol.

Jeremy


[Edit by Jeremy on [TIME]1139686877[/TIME]]

[Bill in MN]

Auto or manual?

[Yellow2]

ye, im looking for a S325 to add to the turbo car, mainily i want the S. THe 2.93 is a great crusing gear with low RPM's turned in each gear. I figured when I go for the S conversion, ill get higher gearing too.
Jay, still wanna trade for my regular 2.93 ?

[smackmybutter535i]

[QUOTE="Bill in MN"]Auto or manual? [/QUOTE]
Manual. What is an s325?

[Bill in MN]

S325 denotes a limited slip 3.25

[bahnstormer]

currenty am running the 3.64LSD up from the 3.46OPEN
not boosting yet but i can already tell the gears are gonna be short
with anything more than 300 hp

=

[Jeremy]

Yea, but those porky e34s need all the help they can get!

Jeremy

[Velocewest]

I'd guess 3rd. Low enough to get 'er spooled up good, high enough to not have to shift for a while.

:~



[Edit by Velocewest on [TIME]1139732883[/TIME]]

[bmwmike]

yeah get some lower gears so you can spool the turbo. A few months ago I test drove one of those pretty new mazdaspeed turbo miatas. The gearing was so short, it was like by the time the turbo spooled and any power accumulated, it was already time to shift. I was probably in 3rd gear at 60, and its probably why the cars stock 0-60 wasnt that impressive for such a tiny car (like 6 seconds).

[Yellow2]

My old Nissan was 4.11 final rear. Open R200 diff. In 5th gear riding like 60mph it was turning like 3600RPM with 15's My 2.93 is nice but Jay and I have some plans for upgrades.