BMW E46 M3 S54 engine

[Ben]

on the subject of M engines, just spent a moment geeking out on this, €25k!-

http://www.racecarsdirect.com/listing/37336/bmw_s14_racing_engine.html

[shane@mbtech]

You clearly know what you're talking about, but I understand literally none of that... God, I'm thick. :smt104

Basically he means if he's fitted a vac or arrow crank then the engine may die sooner than he thinks.

[The Gorilla]

Hi,

Porter- the BMW S54 engine already
has a long stroke at 91mm stroke / with 139mm rod.

With a std Bore of 87mm this makes it
an Undersquare engine.

Therefore it somewhat goes against
the norm for a performance engine,
which are usually oversquare engine,
with Short stroke with long rod.
[oversquare = Bore diam is greater than stroke]

The New BMW M3 V8 [S65] in following
on from BMW's race M3 V8 engine [P60]
follows more traditional race engine
practice of large bore short stroke.

The S65 at 92mm Bore with 75.2mm stroke
its over sqaure and is already well proven to rev
very well, and there is room for longer rods,
[stroker kit] as BMW themselves have already
stroked this engine up to 4.4 [GTS]

The Harmonic balance of the S54 L6 engine
is already on the cusp at its 91mm stoke.

Friction alone can and does kill these engines.

The Increase in the internal 'resonance' by increasing
the stroke beyond the std 91mm stroke is such that
Arrow who designed and made the Stroker
Crank that only Vac sell, decreased the engine
rev limit, on the stroker kit to a max of 7900 rpm.

In essence, you gain some Torque but you loose revs.
Personally for Racing I do not understand this.

Modern day F1 engine make no more that 3-325nm
Torque, BMW S65 V8 does not make bags of torque,
makes less that the BMW S62 [E39 M5], but
it pulls 1500 more rpm, and nobody would
choose the S62 over the S65 for a Race engine.

This is mostly because the increase in the
engine stroke, up from std 91mm to 97mm,
increases resonance, and S54 engine starts to
shake itself to bits internally, via the increased hamonics
of the longer throw/Stroke.

The give away with regard to the harmonic
resonace on the S54 Stroker kits are
that the std S54 Crank damper
is retained and revs are decreased.

Regards,

The Gorilla.

[shimmy]

+1


But black grills and vents are fine