low gear for turbo?
low gear for turbo? hey guys i was planning in getting a turbo kit the t67 from gmr speed and keep it as a daily driver so no more than 7psi of boost , but any ways I got 4.10 gears right now on a 6 speed, i know i have to get lower gears but by reading other post it sounds like it would be better getting 3.23 gears instead of the 3.42 I was planning to get 
. its on a moser 12 bolt too. thanks for your help.
. its on a moser 12 bolt too. thanks for your help. I can assure you that you're in good hands with GMR Speed. They have done WAY more than their share of work on my car and addressing many issues not even related to the turbo system or motor (painted engine bay, re-ran lots of the wiring, cleaned things up, etc..) The 4:10 gears will be way too steep and you'll find yourself shifting from 1st to 3rd cause it will pull through the gears too fast. There won't be a huge difference between the 3.23 and the 3.42. I am running a 3.42 at the moment but will be switching to a 3.00 when I get the 9". Either way you can't go wrong with those choices.
Good question, I have 3.73 in mine and realy would like to put the 3.23's back in. Would I be doing a good thing if I do this once my turbo kit is on? I am planning on using 10psi on my present engine. I also am using a 3800 stall. Please forgive me for temporarily steeling thread.
Sorry for butting in also, but this is something I have been curious about too. Is that the only problem with 4:10's and a turbo is you have to shift to fast or is there more lag or something else resulting with lower gears? Sorry again
With the added power of the turbo it will pull throught the 4.10s before you'll have time to grab for 2nd and also will not allow proper "loading" of the turbo and in turn might not reach full boost in lower gears. Things will be much more fun with the right gearing.
Originally Posted by 93formto98T/A
With the added power of the turbo it will pull throught the 4.10s before you'll have time to grab for 2nd and also will not allow proper "loading" of the turbo and in turn might not reach full boost in lower gears. Things will be much more fun with the right gearing.
I see what your saying but I also have another picture in my head. You say that it may not hit full boost in lower gears, but if your already have that gear maxed out arent you getting there quicker. In other words, using the gears to your advantage by maxing out that gear faster than waiting on the turbo to max the gear out. Wouldnt the faster rev help the turbo spool up quicker for the next gear also?
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No, the turbo doesn't need revs as much as it needs backpressure to spool up. Redline in say 1st w/4.10 is going to me a much lower mph than red line in 1st with 3.23 so you aren't really getting anywhere faster with shorter gearing and high hp.
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I'll agree with cablebandit on this one, I have a M6 also, and put 4.10's out back using a 26x10 tire, which works out great for a NA car, but running my T70, I cannot load the turbo, it seems like I'm constantly shifting and can't create full boost until the top of 3rd. I'm pretty sure I'm going 3.50 with a 9" eventually, or a taller tire. Just my .02
3.73's here... 3.42's might be better for the average LS1, but they're not that bad for me. I'm a HEAVY-*** vert with alot of suspension (LCA's SFC's Adj. torque arm, Adj.PH rod, sways, 12-bolt turbo kit, LOTSA pounds! ~over 4k lbs ? estimated?) and I load up the turbo fine. In first gear I get max boost at about ~4300 rpm, in second at ~3200 or so, and in each gear above that right under ~3k. For the street it's good and controllable. Though, if I was interested in drag racing with slicks I would definitely want a lower gear...
But I would never drag race my 'Vert... It's my baby.
But I would never drag race my 'Vert... It's my baby.
Originally Posted by sparkwirez06
GMC thought 3.42s were the best for there turbo cars that's what's in the Syclone and Typhoon.THANKS
I seriously doubt, however, that it's because of the influence GMC holds over LS1 tuners. THANKS
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Joined: Nov 2001
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From: Toronto, Canada
If you have a Moser/Strange 12 bolt you'll have to check your carrier unit before changing gears. The IV series carrier can only go down to a 3.73, which is the problem I have right now. I wanted to go 3.23 but to do that I have swap my whole carrier to the III series which would make the whole change rather expensive 
For now, I'm just going to live with my 3.73 gears until I can find someone with a III series carrier in good shape willing to swap for my beefier unit.
For now, I'm just going to live with my 3.73 gears until I can find someone with a III series carrier in good shape willing to swap for my beefier unit.
