24V AWD Swap Knowledge Base

[nando]

Here are some pictures of the ix oil pan on the bottom of an N52 block. You can see how much different the N series motors are from the M series. However, having this lower block for mock up is soooo much easier than the S52 block I had to drag around before! that thing was like at least 100lbs, what a pain in the ass!

The N52 block is about an inch longer but that includes the timing cover so it's not a 1:1 comparison.





all I need is a front diff and I can start cutting. I also need to find somebody who can weld it back together..

also, the design of the N52 with the lower main caps being part of this whole assembly means it's really stiff. the stock N52 redline is 7k (compared to an M54 that will shake itself to pieces above 6k realistically). I'm thinking a 10% increase would be realatively feasible, to 7700rpm. Also, MSV70 was actually designed to run without a MAF - but they left it in for emissions reasons, basically. I intend to run it without a MAF as it was originally designed (it uses widebands and an advanced model to run the engine instead). I'll probably start with the 3 stage manifold and work on my own manifold in the future, with a CF airbox. Having no throttles makes things a lot easier...

The head design is also similar to the S54 (same finger/lifter design, but with hydraulics instead of shims and of course VVL). It has smaller ports, valves, and a less aggressive cam, so it's not going to make power at 8500rpm, but there's definitely a lot of potential. Similar to the S54, the intake ports are CNC'd from the factory. I'm looking for about 300bhp, and considering I put down 232whp on a cold day basically stock in my 330i, I think that is achievable with headers, cams, and tuning.

[nando]

If you're referring to machining the bolt seating surface to ensure circumferential contact... that's why we use washers. Yes, I am aware that aluminum would creep under the high contact stress of point loading and drag from tightening a bolt on an as-cast surface.

I'm actually not talking about that. I mostly work with steel. a lot different than aluminum/aerospace.

anyway, the lower half of an N52 block came in. the part that holds all the bearings is about 15lbs. I wonder what the rest of the block weighs? I'm also trying to figure out if the lower part of the block is all magnesium or aluminum. It has embedded steel inserts for the actual bearings to sit into, and I believe the bolts that thread into it from the transmission are steel. So I'm thinking it's aluminum.

[The Dark Side of Will]

Only if they are fully tensioned. And there is a specific surface prep for that. Otherwise, they are in shear and/or tension. You could argue the trans bolts are in both, but there is neither a surface prep or fully tensioned specification for the trans bolts. They would be a TTY bolt otherwise.

I've designed a lot of bolted connections..

And I've worked in aerospace, home of ultra-light structures, bolted joint nerdgasms and carbon faced honeycomb structures.

Are you saying that a bolted joint doesn't work the way it's supposed to if the bolts are not torqued to the design value? Umm... newsflash... ;)

Calculate the torque preload on a bolt at even a modest torque value like 15 ftlbs, and analyze the beam stress in the powertrain at the engine/transmission interface and you'll find that the preload is FAR *FAR* greater than the tension from the beam loading. IOW, the integrity of the transmission to oil pan joint depends on the *STATIC FRICTION* of the interface, NOT the shear strength of the bolt. OBTW, the static coefficient of friction for aluminum on aluminum is ~8, so friction is kind of a big deal.

If you're referring to machining the bolt seating surface to ensure circumferential contact... that's why we use washers. Yes, I am aware that aluminum would creep under the high contact stress of point loading and drag from tightening a bolt on an as-cast surface.

[nando]

Only if they are fully tensioned. And there is a specific surface prep for that. Otherwise, they are in shear and/or tension. You could argue the trans bolts are in both, but there is neither a surface prep or fully tensioned specification for the trans bolts. They would be a TTY bolt otherwise.

I've designed a lot of bolted connections..

[The Dark Side of Will]

There's torsion on the bellhousing. The bolts are in shear. I have just a little bit of experience with this sort of thing. :p

Don't know what you're experience is... but bolted joints depend on friction from clamp load. That's just the way it is.

Don't forget about the dowels guys :D

They only locate the assemblies to minimize eccentricity between the crankshaft and the transmission input shaft.