328 crank in m50 for cheap stroker

[ptownTSI]

i'd like to see more info about this setup. i did not find any info on this in the swap forum, or on the entire board using the search.

is it true you can do the following:

get a 328i crank, put it in an m50, using 328i rods, m50 pistons, and get a 2.8L with 11.25:1 compression? what chip should this be run with. will it run on pump gas?

i wont be able to fill up a daily driver with racing fuel until i move back to sacramento, CA. theres a 76 that stocks VP100 at the pump. so i want it to run on 91.

[ptownTSI]

what other pistons could be used without modifications to lower the compression. is there a thicker head gasket that could be run to get the compression into the 10.8-11.0 range??

[BimmerToad]

I think for the money, you are better off picking up a 328 short block. If you're going through the trouble of a stroker, at least do a 2.9L IMO. As for compression ratio, I too am interested in finding out the maximum allowed on 91 octane. Anyone know? Perhaps a McHenry? :)

[ptownTSI]

right, get the 328i (m52) short block, then put all the other m50 stuff on it?

[ptownTSI]

ok so i think i have it down now.

i need m52 2.8L crank, pistons, rods, wristpins.

right?

[ptownTSI]

anyone got a link for some new main and rod bearings for this stroker kit? that way the whole bottom end is fresh in the m50.

also, it wont need to be rebalanced since the kits are pieced from a matching 328 (if that is true).

[BimmerToad]

Just pick up a complete 328 bottom end. Take the bottom end to a machine shop to inspect the bearings, and if they're in good condition, call it a day. That's what I did :D Bottom end parts need to be broken in properly and once worn in, perform better than one with fresh parts. If you're only doing a 2.8L, get a used stock one, in good condition.

[Addissimo]

IIRC the 2.5 pistons and the 2.8 pistons are the same spec. The 2.8 pistons have a graphite coating, thats pretty much the only difference.

Building a 2.8 stroker is a complete waste of time and money. Just buy an m52 and put a non-vanos head on it.

I think you're looking at around 10.7:1, or 10.8:1 cr on 91 octane with the m50.

[BimmerToad]

The 2.8L pistons have a slightly higher compression vs the 2.5L (10.2 vs 10:1)

[ptownTSI]

ok addissimo but i cant find an m52 2.8 for less than $495, and if i dont need to rebalance anything, i can do the removal/re-install myself.

how much do VANOS m50 heads sell for? i've already committed to buying a complete m50 for $450 with all accessories and wiring.

[raimo]

Why is the 2.8 stroker a waste of money ?

What is the outcome of an m52 with a non-vanos head on it ?

[FredK]

VANOS M50 heads are fairly expensive, probably $350-400 minimum for a good condition head.

It's a lot easier to just "drag and drop" than to swap the internals of the engine. You'd also have to get new rod bolts, which are special stretch bolts that cost $$$. They're around $50 for the set.

I'd just pick up the VANOS M50 that you've committed to, and find a lower mileage M52 and swap the head. You can use the M50 bottom end as a boat anchor, or maybe you can bring two of the pistons to BDC and launch mortars out of it during 4th of July. :) You can probably sell the M52 head to someone for around $350-400 or more.

[ptownTSI]

good idea fred, i never thought of that. maybe i could sell the m50 short block as well as the extra m52 head.... always worth a try.

is there anything you have to change with wiring when you run the m52 block with an m50 head?

[FredK]

The M50 and S50 both have a crank trigger (aka pulse generator) that depends on the harmonic balancer on the front of the engine for a signal (there's a metal pin that's press fitted in there). The M52 and S52 have the crank trigger towards the back of the block, and there's an additional signal wheel installed on M52 and S52 cranks.

You have to install the harmonic balancer from the donor M50 onto the M52 block and remove the crank trigger from the back of the M52. Plug the rear crank trigger hole with a suitably sized bolt/plug.

Besides that, I believe you should be all set. I am not sure, but the only other sensor that goes on the block is the knock sensor. I am not sure if the X52 engine and X50 engine knock sensors are compatible. But to be extra sure, you can just transfer the sensor over to the M52 block.

Good luck on your project! I believe r3v member Permit has essentially the same engine (M52 with M50 head), or something very close to it.

[aeryk7]

I have a full m52 block pistons,rods,crank. i'll sell it for $250