M52TU stroker ideas

[dave.a.cote]

Correct - if you are using 84mm bore 2.8 pistons, not 2.5 pistons - and you have to shave 0.38mm off the top to get to 11:1. There is enough material there to do it, or at least that is what I did.

[ChaseN]

Correct - if you are using 84mm bore 2.8 pistons, not 2.5 pistons - and you have to shave 0.38mm off the top to get to 11:1. There is enough material there to do it, or at least that is what I did.

Ok, so am I SOL on keeping my 2.5 pistons? Is there a difference between M52 and M52TU pistons? The BMW training publication I have says that the M52TU pistons are "carried over" from the M52, but RealOEM lists them as a different part number....Hmmmm

BTW, thanks for all the awesome help/ideas guys

[nrubenstein]

Seems like a lot of effort and money rather than just getting an M54B30 for a couple K.

[dave.a.cote]

Bah, where's the fun in that?

[ChaseN]

Seems like a lot of effort and money rather than just getting an M54B30 for a couple K.

I can convert to OBD1, stroke, and maybe even snag a set of used cams with this motor for way less than I've ever seen a M54 priced at (that I would still have to convert to OBD1 & get rid of the return-less fueling system). Plus, to be honest, I want an engine to tear apart and fiddle around with.

Also, knowing how much power you made on a OBD2 b25 with stock internals keeps me from wanting a M54 too much more.

[nrubenstein]

I can convert to OBD1, stroke, and maybe even snag a set of used cams with this motor for way less than I've ever seen a M54 priced at (that I would still have to convert to OBD1 & get rid of the return-less fueling system). Plus, to be honest, I want an engine to tear apart and fiddle around with.

Also, knowing how much power you made on a OBD2 b25 with stock internals keeps me from wanting a M54 too much more.

The exact same setup on an M54B30 put down 217 at the wheels, FWIW. That's non-trivial. The amazing thing is that it pretty much hit peak hp at 5500 and ran it to redline.

I'll be swapping in a 2.8 bottom end (it was free) at some point, so that'll be interesting to see.

Edit: FWIW, the M52TU has a returning fuel rail which is plug and play on the M54 manifold should you end up using it.

[ChaseN]

The exact same setup on an M54B30 put down 217 at the wheels, FWIW. That's non-trivial. The amazing thing is that it pretty much hit peak hp at 5500 and ran it to redline.

I'll be swapping in a 2.8 bottom end (it was free) at some point, so that'll be interesting to see.

Edit: FWIW, the M52TU has a returning fuel rail which is plug and play on the M54 manifold should you end up using it.

I know the M54's advantage in power isn't trivial (BTW, very nice numbers), never said it was - in fact the M54 is probably my favorite pre-N series non-Sxx motor (I would run one over a US S5X in a heartbeat). Its just in this application I don't need the power vs. the extra cost, and though I would prefer it the $$ just doesn't make sense to me for the car it's going into.

I really just want a moderately powerful, efficient, fun engine. I already find the car fun with an M20, IMO everything up from there is just a benefit. I've already got my M3 to tickle my "fast" itch.

[nrubenstein]

I know the M54's advantage in power isn't trivial (BTW, very nice numbers), never said it was - in fact the M54 is probably my favorite pre-N series non-Sxx motor (I would run one over a US S5X in a heartbeat). Its just in this application I don't need the power vs. the extra cost, and though I would prefer it the $$ just doesn't make sense to me for the car it's going into.

I really just want a moderately powerful, efficient, fun engine. I already find the car fun with an M20, IMO everything up from there is just a benefit. I've already got my M3 to tickle my "fast" itch.

Fair enough. I'll admit that I have an irrational desire to make a 2.8 M20. :)

[weaksauce]

ok guys, i'm reading thru this and here is where I am at.
I have a 97 m52 out of a e39
full wiring harness for OBD1
and I can use either my s50 crank or the m52 crank in my build with the stock m52 pistons and rods.

will i gain anything with going to the s50 crank I have?

[Leo_328i]

S50 crank will give you a longer stroke and increase your capacity to around 2.9l instead of 2.8. It would also increase your compression ratio.

[nando]

M52B28 pistons have very thick crowns, so you can machine them down without any worries at all.

if you've already got an S50 crank I think that is a no-brainer. The extra displacement is almost free.

[weaksauce]

how about a thicker head gasket versus machining the pistons? seems like you could ge thte extra .5mm by going a .09 MLS gasket versus the stock .07 thickness, right?

[nando]

that's the wrong way to approach it IMO.

[weaksauce]

that's the wrong way to approach it IMO.

wrong as in it won't work or wrong as in that just isn't the way you would do it? if it won't work, why?

you're only shaving .5mm off the top of the pistons, why not just lift the head .5mm and save the machining cost? i mean a .09 or a .1 HG isn't even that thick.

maybe i'll try it and report back when i've broken something.

[Hornung418]

BUMP!

Why can't we remove the sleeve of the M52TUB28 and bore it out to 85.8 after re-sleeveing the cylinder wall? I think the key to the harmonic issue is to keep the Bore/Stroke square or under square, in the alloy blocks. So by bumping the Bore up to 85.8mm and the Stroke up to 85.8mm, you get a Displacement of 2.976 Liters and have a square stroke, hopefully avoiding the harmonic issues that plague the M54B30 when used as a track car.

Thoughts? Is it worth it?