2.7L stroker engine

[roycem3]

Has anyone done a 2.7L stroker with the s52 m3 crank? The M3 has a stroke of 89.6mm and the crank is forged just like the diesel, but needs a sleeve in the front for the oil seal. Custom pistons and rods would need to be made.

With this setup in the m21 you get 2703cc (80mm bore x 89.6mm stroke)

Here is the m21 engine specs: http://www.usautoparts.net/bmw/engines/m21.htm
(take a look at the valve lift)

Here is the m51 engine specs: http://www.usautoparts.net/bmw/engines/m51.htm

Here is the m57D30 engine specs: http://www.noellemotors.de/uploads/medi ... S-1_06.pdf

The m21 has 81mm stroke and 80mm bore
The m51 has 82.8mm stroke and 80mm bore
The m57D30 has 88mm stroke and 84mm bore
The m57TUD30 has 90mm stroke and 84mm bore

[DieselBoost]

just checked that s52....

only way to know does it fit is take measurements and then think about what modifications it needs...

only thing what does me wonder is that m52 newer engine family than m21 which is based old m20 family engines

[roycem3]

The s52 cranks fits in the m20 block. People are using it to make 3.0L stroker (84mm x 89.6mm) in the m20 engine. The difference is, it needs a sleeve in the front of the crank to use proper front m20 engine seal. s52 uses a chain to drive camshaft, so that is why the sprockets are different.

You can use a m52 crank (84mm stroke) which is forged steel crank also, if you don't want to go too far. It came in the 2.8L engine (Us spec 328i, 528i). If you decide to go this route you end up with 2534cc.

I am having the sleeve made, so if anybody is interested just send me a PM. I can have extras made.

[DieselBoost]

Wow.... sounds extremely interesting now...

maybe in future i will do this too!

[winfred]

spacer is easy to make if you have access to a lathe, can be done with a hacksaw and file but wouldn't fit with the title of easy any more, take the hub that comes on the m52 and cut right behind the part with the bolts, for use in a m20 you need to have .720" or so to position the cam belt drive and harmonic balancer


you need to knock a little off the washer that goes on the crank bolt, if you don't it may bottom out on the end of the crank before it gets tight

[DieselBoost]

one problem with s52 crank is that with it, you must use short rods that are already short in m21 engine.
this makes rod to go very high angle
and it may do some lost in power and durability

[roycem3]

You can use stronger/longer custom rods with new pistons. By getting pistons made you can move the pin location to accomodate the longer stroke. The new pin location would also help determine the rod lenght. If you run bigger turbo you can lower the compression down a little with the new pistons to run more boost.