Upgrades: differentials and limited slips!

[Skyline]

Originally Posted by sedc

It's still going to be sluggish. The M54 needs another 100hp to comfortably move the truck. I'm thinking about a supercharger or turbo.

The cost of that would be much, much higher than selling your 6 cyl and buying a V8. And with forced induction, you'd probably lose any gas mileage advantage you had with the 6. In the used market there's very little price difference between the 6cyl and V8 cars now, especially with the early editions. I guess $4.30 premium gas has helped that. The V8 cars have very decent acceleration, tow quite well, and cruise effortlessly at highway speeds. I get 20 mpg on the highway at 80 with my V8, which is not too bad. Around town mileage sucks, but it's nice to have the power.

But great write up on the diff swaps.

[Green Dragon]

Just checked the specs on my wife's '04 e83 x3 6-speed manual. 3.64 final drives are used. Interesting. The ratios in the gear box are massaged as well. That would account for her X having a more "friendly" car-like driving attributes when it came to shifting. Her X also weighs about 500 lbs lighter at just over 4000 lbs. 1st gear is better and easier to live with, but still some what tall. Not sure how many e83 owners tow but it does have that option.

My guess, BMW is addressing the M54's lack of low end torque and 'rev' happy nature to move the weight around. Once you get 'er moving, the I6 power delivery is silky smooth with more urgency as the revs build. That is truly when the m54 is in its element and accounts for, at least in my mind, why they choose the gearing.

Sedc, I love the idea of an S54 powered e53. I know its been done, but I don't know much about it. The S54 would defiantly be a screamer, and would naturally have to be, to tap into its upper power reserves where that engine just thrives. If you go that far, you might tune it for a little more torque delivery down low. My guess is that you wouldn't give up anything that the M54 offered. Good Luck which ever direction you take, S/C'ed or whatever. Keep me posted.

[sedc]

Originally Posted by Green Dragon

Sedc, I love the idea of an S54 powered e53. I know its been done, but I don't know much about it.

It's a lot of work. We did an S54 into an E39 wagon, many many headaches.

Originally Posted by Skyline

The cost of that would be much, much higher than selling your 6 cyl and buying a V8.

Sure, but three reasons why this isn't an option for me: 1) I haven't yet driven a V8 BMW, of any variety, that felt balanced, 2) I spent a couple years wrenching BMWs professionally, and I know V8 E53s are less reliable than I6s, and most importantly, 3) No manual trans for V8 E53, and no easy remedy for swapping one.