3.0 Power Adder Options

[nick325xit 5spd]

Yeah, if I found a plausible N62+6MT+xDrive swap, I'd probably pick up a 4.8is.

[PropellerHead]

Originally Posted by nick325xit 5spd

Yeah, if I found a plausible N62+6MT+xDrive swap, I'd probably pick up a 4.8is.

It's that MT that gets ya. I wanna do an LS if my motor goes, but I don't wanna lose XDrive.

[Bdc101]

Is your 4.8iS converted to a manual, Propellerhead?

[nick325xit 5spd]

Originally Posted by PropellerHead

It's that MT that gets ya. I wanna do an LS if my motor goes, but I don't wanna lose XDrive.

Yeah. But the truth is that I really don't mind the M54. Do I want a little bit more? Sure. But do I really need it? No. And if I were motivated enough to do the work, I have the parts to add a good bit of power.

[7to3_enthusiast]

Think you guys have talked some sense into me. Does the 4.8 have the same timing chain guide issues the 4.6 has? I really miss my 4.6 power, it just broke down too often even with my wife driving (I never hear the end of it). They sound so good tho ....maybe I'll look for one again, hmm.

[nick325xit 5spd]

Originally Posted by 7to3_enthusiast

Think you guys have talked some sense into me. Does the 4.8 have the same timing chain guide issues the 4.6 has? I really miss my 4.6 power, it just broke down too often even with my wife driving (I never hear the end of it). They sound so good tho ....maybe I'll look for one again, hmm.

N62s eat the valve stem seals.

As I said earlier, the 4.6is was the worst X5 out there reliability wise. Unique engine, unique transmission, all highly stressed versions of pretty unreliable base components. The ZF6 is a great transmission, and the N62 is much better than the M62.

And don't forget that the N62 4.4i has 315hp. You may prefer a lower specced 4.4i with less to go wrong and a little less stressed parts vs. the 4.8is.

[7to3_enthusiast]

Originally Posted by nick325xit 5spd

N62s eat the valve stem seals.

As I said earlier, the 4.6is was the worst X5 out there reliability wise. Unique engine, unique transmission, all highly stressed versions of pretty unreliable base components. The ZF6 is a great transmission, and the N62 is much better than the M62.

And don't forget that the N62 4.4i has 315hp. You may prefer a lower specced 4.4i with less to go wrong and a little less stressed parts vs. the 4.8is.

Definitely can confirm that, timing chain guide broke while traveling for work resulting in a 220 mile tow back to my garage for repair. Shortly after that the transmission started slipping, not to mention a water pump, alternator, and coil pack failure. Meanwhile I could hop in my over 800 crank hp unopened turbo s54 and drive night and day without one single engine or transmission related issue for the same amount of time . I do love the bimmer I6's.

[PropellerHead]

Originally Posted by Bdc101

Is your 4.8iS converted to a manual, Propellerhead?

Oh Lawd, I sure wish it was, but no.

[PropellerHead]

Originally Posted by nick325xit 5spd

N62s eat the valve stem seals.

Can confirm. I did them a bit on the proactive side because of the water pipe issue. At the time, a seal job was ~$6500. They did the seals cause they were 'in the neigborhood' for $3000 added onto the AGA install. Of course, I ended up going pretty deep and replaced most wearables in the general vicinity. But that was something like 6 years and ~80k miles ago. Haven't heard a peep since.

The '04 4.4 though *will* smoke on a hard accel after idle and I am getting some oil consumption. I can *feel* the seals wanting to drop. It's at 55k miles.

[e39_touring]

I'll throw my two cents in here since I've kind of been thinking of doing the same thing as you are. I've concluded that the M54 engine will be fine with boost provided you don't become addicted to it and overdo it and also provided that your tune is good (never lean). The N54 has basically the same bottom end, 10.2:1 cr and runs 8 psi of boost for ~300 chp from the factory. An M54 with 8 psi of boost properly tuned will do just fine under the rigors of towing.

A small-ish turbo or positive displacement supercharger will be a better match for a heavy SUV like the E53 compared to a centrifugal blower like others have already mentioned. The centrifugal blower won't 'feel stronger everywhere' but will rather come on stronger and stronger as RPM's build with little difference being felt coming off a stop and at lower RPM's. Not really ideal for towing.

Upgrading the cooling and drivetrain is not a necessity, but making sure it they are in tip top shape is. IIRC, the auto 3.0 is rated to 5 or 5.5k lbs while the manual is 6k. Keep your loads within those limits, and don't do extended full throttle pulls at max load, and you'll be fine.

However, if your trans is already heating, it's already slipping, and adding power will make its failure that much quicker. The E53 GM trans is electronically controlled and has a series of clutches and solenoids to actuate gear changes. Once a gear is locked, there should be no slippage, and the heat generated should be minimal (i.e. towing or not, your ATF should roughly maintain engine coolant temps since it is cooled & heated by the engine radiator). If it's heating, it means that you trans is slipping excessively during gear changes, which can be more frequent with towing.

I've also decided that if I go the V8 route, it won't be in a BMW but something domestic with a more robust drive train like a Trailblazer SS or Jeep Grand Cherokee SRT or the like. A little less refined than the bimmer, but they sure can take a beating in the drivetrain dept.

Keep us posted on what you decide to do!