3.0 Power Adder Options

[7to3_enthusiast]

Originally Posted by nick325xit 5spd

Most blower options are centrifugal and won't add much of anything for low end torque. Also, I'm not sure why you think that a bunch of boost will add less load / heat to the drivetrain than a few more RPMs?

As for the weak link when going forced induction, well, people usually eat a couple motors when trying to do something unusual. I don't know of anyone who has built an FI M54 for towing. That's VERY different from building an FI M54 for giggles or track. I also wouldn't have much expectation of longevity from the transmission. After that, IIRC, the 3.0i auto got a bunch of downrated other drivetrain parts that I'd want to swap to V8 / 3.0i manual spec.

Boost actually doesn't add that much more peak stress to a bottom end. You'd be surprised to find that you'll stress an engine rods and crank from trying to add 1,000 more RPMs than you will adding a few pounds of boost. Of course if you can always get out of hand with adding power, but that's not what I'm going for here.

[7to3_enthusiast]

Originally Posted by nick325xit 5spd

In terms of getting what you want, you'd want a small turbo setup if the goal is low end torque. But, again, I'd advise against this. You're going to spend a lot of time fighting it.

Thought about this initially as well. Would definitely give the low end tq since the load could build more boost. BUT my turbo cars over the years I've always fought with reliability and heat issues where my SC'd cars have not. I've seen several stock motor M54 from our local BMW shops push 400-450 whp unopened so not too worried about the motor. Just have no experience with the transmission so far.

[Bdc101]

Originally Posted by 7to3_enthusiast

My X5 trans overheats when trying to stay at highway speeds while towing the GTR. Mainly because to keep up with the flow of traffic I have to give it enough throttle that it downshifts to 4th and my RPMs typically are around 4500+.

You are most definitely not going to solve your transmission overheating problem by adding boost so you can have more HP at lower RPM. If you tow a 3800lb car with a 1,500+lb trailer you are right at the limit of the 3.0 auto's towing capacity (5,500lbs). It's far more likely that your transmission is in need of maintenance or at best an external cooler. Then you could just use the throttle normally in your current motor instead of adding horsepower so you can overheat your transmission even more by transmitting more horsepower (and thus more heat) through it.

[nick325xit 5spd]

Originally Posted by 7to3_enthusiast

My X5 trans overheats when trying to stay at highway speeds while towing the GTR. Mainly because to keep up with the flow of traffic I have to give it enough throttle that it downshifts to 4th and my RPMs typically are around 4500+. Increase in RPM creates friction and thus heat at an exponential scale. Hence why diesels are typically so well mannered for towing.

Why don't you add a transmission cooler? You will need that no matter what, and that's a lot cheaper and more reliable than trying to brew up an FI solution.

As for diesels, well, the thing about them is that they HAVE to be force fed to make enough power to perform well. And they are built from the factory to withstand all that. Also, my diesel truck has a transmission cooler and a trans temp gauge from the factory because, well, they still overheat.

[nick325xit 5spd]

Originally Posted by 7to3_enthusiast

Boost actually doesn't add that much more peak stress to a bottom end. You'd be surprised to find that you'll stress an engine rods and crank from trying to add 1,000 more RPMs than you will adding a few pounds of boost. Of course if you can always get out of hand with adding power, but that's not what I'm going for here.

It adds different stress. BMW engines are largely built to withstand revs within reason. The big problem on the M54 is the lack of an oil pump chain guide/tensioner.

[nick325xit 5spd]

Originally Posted by 7to3_enthusiast

Thought about this initially as well. Would definitely give the low end tq since the load could build more boost. BUT my turbo cars over the years I've always fought with reliability and heat issues where my SC'd cars have not. I've seen several stock motor M54 from our local BMW shops push 400-450 whp unopened so not too worried about the motor. Just have no experience with the transmission so far.

Were literally any of those M54s being used for towing? I bet the answer is no.

[7to3_enthusiast]

So it sounds like there are a few deterents on increasing power output on the E53 3.0, but no one has really tried? Surprising to me since the BMW inline 6's of this era are pretty impressive, which I can't say the same for the V8's they made which ESS and dinan made supercharge kits for.

Upgrading the trans cooler will solve the overheating issue, which is fine, but anyone who has towed the max rated load with the 3.0 probably can share my experience with it needing a bit more power.

[nick325xit 5spd]

Originally Posted by 7to3_enthusiast

So it sounds like there are a few deterents on increasing power output on the E53 3.0, but no one has really tried? Surprising to me since the BMW inline 6's of this era are pretty impressive, which I can't say the same for the V8's they made which ESS and dinan made supercharge kits for.

Upgrading the trans cooler will solve the overheating issue, which is fine, but anyone who has towed the max rated load with the 3.0 probably can share my experience with it needing a bit more power.

I literally referenced a member of the forum with a blower on his M54 in this thread.

I still think that a well maintained N62 is a much better option that'll give you more of what you want and cost a lot less to get there. And the ZF 6-speed auto kicks the shit out of the GM box that all 3.0i automatics got.

If you said to me "I want a manual X5 and I want to tow with it," then figuring out ways to add power to the 3.0i would be one thing. (And I have towed with my 6MT X5.) But I wouldn't let your bad experience with what has to be the least reliable E53 in existence rule out the V8s completely.

[Bdc101]

I also tow a camper trailer regularly with my 3.0i/5MT X5. I weighed the trailer last year on a trip home, and it ends up around 4,000-4,500lbs, with a gross vehicle weight of over 9,000lbs fully loaded. So my X5 with trailer is probably slightly lighter than your X5 with trailer, but has a lot more aerodynamic drag on the highway, being a short but full-width and full-height trailer.

Of course with the 3.0 it takes a lot of effort to maintain speed while climbing hills, but I am able to maintain speed on the highway without downshifting. Especially at sea level I don't have any trouble on the highway in 5th gear unless I am trying to go 75mph or there is a serious headwind. (I live at 4,000ft and there's a noticeable difference at my elevation, but still it is possible.) Granted I do not own the automatic trans, but based on this experience I would assume something is wrong with your transmission if it is overheating just trying to maintain speed on the highway with your trailer.

(On a further note: I climb a mountain pass with my fully loaded trailer at least once every year, going up to about 5,500 feet on steep grades in the middle of the summer. These trips always have multiple climbs where I am spending 10 or more minutes at WOT, usually switching between third and fourth gear, at 95+ degrees outside, and I have never had a problem. I'd challenge anybody to think up a scenario that's tougher on a motor/transmission combination than spending ten straight minutes at WOT in between 4,500-6,000 rpm!)

[80stech]

Actually it's the opposite, increased RPM gets rid of heat faster, especially apparent on a diesel. Typical "I tow a race car" thinking.