3.46 final drive for Single turbo Use

Island Road · 03-09-2012, 01:50 PM

I will be upgrading to single turbo in some time due to the fact my turbos are shot and I’m not replacing them with stockers.

With that being said I need an LSD, I have 6sp 3.08 welded now and I have access to an auto punkin with a wavtrac already installed. I mainly use the car on the weekends and my goal is the occasional track use, as many as I can fit into the NE season. I don’t care about MPG but rather performance and actually putting power to the ground. I will have a square setup 265/35/18x9 all around. I know a lot of the 135 guys switch over to the 3.46 and also the M3 has this gear ratio and they are putting down some big numbers if they are supercharged(M3).

I feel as though with the auto dif I would always be struggling to actually have usable power, I don’t care about Top speed as living in the east coast I don’t often have a chance to go faster than 150mph anyway. Mexico is far away..

So what do you guys think, has anybody went from 3.08 to 3.46 pushing 400whp + what are your main issues should I just get an LSD for my current car?Anybody else thinking of switching over to 3.48 with Single turbo also to be installed? Pro’s or Con’s

R1000K3 · 03-09-2012, 03:27 PM

3.08 will be better for your goal with a single snail instead of stock turbos.

GeorgiaTech335coupe · 03-09-2012, 03:41 PM

It all depends on what you want. You need to match up the gearing with your tire size and your goals. My example for instance: I am currently running MT with 25.9" tall tire, I run the 1/4 mile, this blows because now my 3rd gear goes up to almost 111 and 4th goes up to 147. This isn't good for a FBO+meth drag car, as I'm barely in 4th gear when crossing the line. The 3.46 would be soo much better. I too am going single turbo route. This should put my trap speed in the 130s neighborhood I would expect. This changes a lot. Now ending 4th at 147 doesn't look so bad. If I put in a 3.46 gear, 4th gear would end at 131. This wouldn't be good as I would have to shift into 5th. Therefore I am keeping my 3.08. A simple answer is you'll get quicker acceleration with the 3.46, but you have to make sure you are ok with mph ranges.

03-09-2012, 01:50 PM	#1
Island Road Major 167 Rep 1,261 Posts Drives: 335i Join Date: Mar 2011 Location: Boston iTrader: (5) Garage List 2008 335i [10.00]	3.46 final drive for Single turbo Use – Worth the upgrade? I will be upgrading to single turbo in some time due to the fact my turbos are shot and I’m not replacing them with stockers. With that being said I need an LSD, I have 6sp 3.08 welded now and I have access to an auto punkin with a wavtrac already installed. I mainly use the car on the weekends and my goal is the occasional track use, as many as I can fit into the NE season. I don’t care about MPG but rather performance and actually putting power to the ground. I will have a square setup 265/35/18x9 all around. I know a lot of the 135 guys switch over to the 3.46 and also the M3 has this gear ratio and they are putting down some big numbers if they are supercharged(M3). I feel as though with the auto dif I would always be struggling to actually have usable power, I don’t care about Top speed as living in the east coast I don’t often have a chance to go faster than 150mph anyway. Mexico is far away.. So what do you guys think, has anybody went from 3.08 to 3.46 pushing 400whp + what are your main issues should I just get an LSD for my current car?Anybody else thinking of switching over to 3.48 with Single turbo also to be installed? Pro’s or Con’s
	Appreciate 0 Tweet Quote

03-09-2012, 03:27 PM	#2
R1000K3 Major 55 Rep 1,311 Posts Drives: 335i MT Join Date: Jul 2009 Location: USA iTrader: (0)	3.08 will be better for your goal with a single snail instead of stock turbos.
	Appreciate 0 Quote

03-09-2012, 03:41 PM	#3
GeorgiaTech335coupe Lieutenant Colonel 76 Rep 1,883 Posts Drives: Black BMW 335i coupe Join Date: Mar 2007 Location: USA iTrader: (0)	It all depends on what you want. You need to match up the gearing with your tire size and your goals. My example for instance: I am currently running MT with 25.9" tall tire, I run the 1/4 mile, this blows because now my 3rd gear goes up to almost 111 and 4th goes up to 147. This isn't good for a FBO+meth drag car, as I'm barely in 4th gear when crossing the line. The 3.46 would be soo much better. I too am going single turbo route. This should put my trap speed in the 130s neighborhood I would expect. This changes a lot. Now ending 4th at 147 doesn't look so bad. If I put in a 3.46 gear, 4th gear would end at 131. This wouldn't be good as I would have to shift into 5th. Therefore I am keeping my 3.08. A simple answer is you'll get quicker acceleration with the 3.46, but you have to make sure you are ok with mph ranges. __________________ Legal Disclaimer: Anything I or anyone else says about my vehicle on this website(e90post.com or any affiliated or nonaffiliated sites), pertaining to modifications, is only to gain acceptance from my/our peers, and does not actually represent anything actually existing on my car, and thus, cannot be held against me in any issues, i.e. warranty claims, that may arise.
	Appreciate 0 Quote