63,000 Mile M54 swap. Pics -- Engine Porn

[tecboy99]

Originally Posted by Green Dragon

Joshdub is correct. ATI makes a really nice but spendy harmonic balancer/pulley. I would contemplate a new oem unit at a minimum and replace it intervals as they don't do as well of a job with age and mileage. I just got access to a CNC mill. I'm looking to make one and try it out. Harmonics is an interesting bit of physics. The BMW I6 dosen't typically manifest harmonics like this till the 6th order. However, there are some nuances with the m54b30 that contribute to it appearing in an earlier order above 6k rpm. Aluminum block and the long stroke may contribute to this. BMW did revise the harmonic balancer for the m54b30, and it seems most of the failures occured with early M54's ('01 or so) and very frequent with motors that were tracked, very high and long sustained RPM's above 6k. Street driven vehicles have not seen but a very small number of failures that I've gathered and were early production.

Going to a single mass setup, you will want to run a sprung clutch disk. I have sourced a 22 tooth 240mm clutch disk with your choice of performance organic/kevlar, etc. About $150. You can source one through clutchmasters as well, but when I called them they quoted about 300 for one. (I'm leading you down the path of a budget build UUC kit...you can hate me.) You can use many of the glorious lightweight flywheel offerings for the s52 and 330's etc. ( just check the ring gear for the starter.) There are machined adapters for the pilot bearing to be pressed in to adapt it. Cluthmasters also makes one now for us 6-speed guys for about 500. Fidanza makes the one for UUC. Its a 13.5lb flywheel. I wouldn't go below that. There are some nice forged cromoly ones that are 14.5 lbs for around 250-ish. UUC uses the pressure plate sourced from a euro M3, but there are other good options that are less money for similar spec. (get rid of the self adjusting clutch)

By going away from the dual mass, your removing a harmonic balancer of sorts from the rear of the crankshaft. This is where you get transmission chatter as the power pulses are not as dampened as well and are transmitted down the drive line. Its minimal, but present. The lighter you go, more apparent it becomes and affects moment of inertia, etc. I'm giving a call to Rob L on Monday to discus it with him and I'll share his input. BY MAKING these changes, you maybe making things better and not worse because your are changing the dynamics. It could go the other way too. I'll add more soon.

Wow, awesome info! Please do keep me updated. I'd really love a UUC kit, but cost is a huge factor. From what you said, it sounds like we could get a very similar kit for just over half of the UUC price. I would be very curious to know if it feels any faster after dropping all that rotational mass from the stock kit.

[PropellerHead]

Originally Posted by tecboy99

I would be very curious to know if it feels any faster after dropping all that rotational mass from the stock kit.

I've had a LTW Flywheel in my E39 for about 10 years now. Chatter is def there on idle though not present when the clutch is depressed @ idle.

As for 'feel' it's tough to say. What you 'get' is up to redline much more quickly. Revs are matched way more easily since the throttle response is much- what.. snappier? I guess? Tough to find the words.

But the opposite is also true- revs with the LTW flywheel 'fall' away even more quickly than they climb. So what you get is the need to be a bit more on point with your shifts so that the engine revs are closer to the transmission rotation. The stock flywheels mass keeps it moving much more closely in the use of a clutch, so it's easier to drive.

And that gets you back to why you'd want one in the 1st place. In every day driving- the kind I do in my E53- I don't think I'd want a LTW flywheel. I'm not even sure I should have done one in my sedan. It's a sedan after all.

But if you're trailbraking, double clutching, and using every second to get as much out of your drive as possible, the trade offs might be worth it. Like most of us, I'm still willing to pay the price for the benefit of a mod beyond what a lot of folks would. It's the essential non-sensical part of what makes us enthusiasts.

[Green Dragon]

Originally Posted by PropellerHead

I've had a LTW Flywheel in my E39 for about 10 years now. Chatter is def there on idle though not present when the clutch is depressed @ idle.

As for 'feel' it's tough to say. What you 'get' is up to redline much more quickly. Revs are matched way more easily since the throttle response is much- what.. snappier? I guess? Tough to find the words.

But the opposite is also true- revs with the LTW flywheel 'fall' away even more quickly than they climb. So what you get is the need to be a bit more on point with your shifts so that the engine revs are closer to the transmission rotation. The stock flywheels mass keeps it moving much more closely in the use of a clutch, so it's easier to drive.

And that gets you back to why you'd want one in the 1st place. In every day driving- the kind I do in my E53- I don't think I'd want a LTW flywheel. I'm not even sure I should have done one in my sedan. It's a sedan after all.

But if you're trailbraking, double clutching, and using every second to get as much out of your drive as possible, the trade offs might be worth it. Like most of us, I'm still willing to pay the price for the benefit of a mod beyond what a lot of folks would. It's the essential non-sensical part of what makes us enthusiasts.

Thanks Prop! Very well put. I've only driven an e36 m3 with a LTW, and your experience with a heavier vehicle closer in character to an X5 is perfect. I wish I could remember more but it was a while ago. Would you say that the effect of the LTW is more pronounced in gears 1-4 on acceleration kinda like a virtual weight reduction since its a dynamic rotational mass? It seemed like that on the M3. The car felt lighter by about 500 lbs in 3rd. Similar to a differential swap to a higher ratio if that makes sense? It just kinda felt like more torque was being applied to moving the car forward and on the track coming out a corner or on acceleration, I felt an increase in overseer tendency till I got used to it and adjusted the throttle back, as the rear tires were braking loose sooner with the same input. Our lap times were slightly quicker as well. We put fresh tires on because, they were close to spent honestly, but to our amazement, as we were somewhat doubtful, the car carried over what seemed like a virtual weight-loss and extra torque and our lap times reflected this. We didn't have to push the car nearly as hard.

This is all anecdotal to a track expirence on an M3, but my gut thinks this will translate well to the x5. It's already a very different animal and has responded well to mods. A once fun but lethargic 4500 lb 3.0 has become very nimble and quite quick. It just seems that any improvements (and a few mistakes ) I make seems to be quite noticeable. I would normally think the opposite is true, being heavy and light on power, but I guess if you're doing things right, you've got nowhere but up to go. She's still my daily driver, just extra sprited and on point. If your ever back in these parts again, stop in for lunch. You can have my keys. It's not your 4.8is, but I think you'd like it. Thanks again brother.