Forgot to mention that piston accelerations also have a lot to do with wear, and that is a function of stroke and RPM. Cam wear is also a function of spring pressure, profile, and RPM. Hotter cams mean stiffer valve springs, and faster valve acceleration, which means harder landing when the valves close, which can mean more wear. Basically, the faster you spin anything, the faster it will wear, and it is not a linear relationship. It is probably more like an exponential relationship, e.g. a motor may wear at rate x at 4krpm, but may wear at rate 4x or higher at 8krpm.
I haven't been on this site for a few weeks, and this is a fascinating thread for a couple of reasons. FYI, Botond, I looked into swapping an S50 into my 325i when my M20 spun a bearing last September. My BMW mechanic (he worked at TMS for 7 years) gave me a $10K price for the swap and that's when I backed off. But he was going to charge me $95/hour. I say go for it (you already are!) FWIW. As Paul has indicated, it may not have been a coincidence that I have a 4.10 LSD and that my M20 spun a bearing within 18 months of my buying the car. I only tracked it once and AutoXed it twice. I think one of its previous owners probably tracked it almost-to-death. But I agree with Z31 and MGarrison that the 4.10's everyday zoom-zoom in the lower gears more than makes up for the increased wear I give it on very occasional longer trips at sustained high rpms. I would put my Conforti chip in for added fun, but I don't really need even less fuel economy and more engine wear. I may be dumb but I'm not that dumb. GO BOTOND!
4.10???? Holy crap. I do a LOT of highway driving, over 20k a year, so this 2.93 will be just fine. $10k for an S50 swap? That's extremely excessive. For $10k, you can get a rebuilt S50, transmission, all the other parts needed, labor, AND still have enough left over for another decent E30! Of course this isn't with a $95 labor rate... I was just recently quoted by three different people. One says he could do it for $1500 (I seriously doubt he knows what he's getting himself into), another says for $2500 (he's done it before, including his own car, and this includes the wiring harness adapter that he makes), and the last one for about $3000. The first two are individuals, the last one is a shop that I highly trust. So, once again, 10k seems highly excessive to me...
From those figures, a shop can do an S50 for about $7k including any parts needed. Out of curiosity, do any of them include the exhaust work that will be necessary? If not, make sure you find a good muffler shop that has done lots of custom work (no hackery please!) and make sure they show you some examples and will be comfortable making exhaust for a BMW using mandrel bent pipe. $3k would buy you about 40 hours at our shop, which would be about enough to handle any problems, so that seems very reasonable to me. Terry Sayther automotove charges $3k for a 95 or earlier swap and $4k for an OBD2 swap, PLUS $1k for "misc. charges" that are probably in place to cover any problems with your car that will require fixing before they can drop in the M/S50.
Botond, just get some buddies and do it yourself for the love of all that is holy. Paying someone to do the swap is a waste. Do it yourself and then you'll know everything and be able to work on it. That $10k isn't all that excessive either (again seems like you haven't actually priced stuff) my obd-I S52 swap is going to approach 6k in parts + 3k in labor, not that far off. Rebuilding a 24v motor is painfully expensive, do you know what valvetrain parts alone cost? We just pulled my m20 yesterday, making progress!
And WHO is going to help me do this? WHO? Don't you think I'd have someone help me do it if I knew someone who could? Depending on my brother to help me do it is like depending on a drug addict not to blow the money he makes on drugs. It's just NOT going to happen. He is the most undependable person I know, despite his knowledge and ability to do it. And he is the ONLY one who I know that can help me do it, unless one of you are willing to drive down here? I didn't think so.
Fly me out there, buy me a ticket to Oktoberfest and find me a track car to use for the Race School, and I'll come help you.
I can't find you a track car, but I can definitely buy you a ticket for Oktoberfest and fly you out here... you down?
