S50 with b20 flywheel

[dicko]

I have done a bit off measuring and reckon that I can run my s50b32 with a m20 b20 flywheel if I use the m20 starter .
I know some of you on here have done the same on the m50 /m52 which is more or less the same block right or am i missing somthing here ,
you may wonder why I want to do this , its because the engine came with no flywheel or clutch , I am not a fan of dual mass flywheels and I have a nearly new m20 flywheel gathering dust .
I have found a Sachs uprated clutch kit thats rated at 450nm so that should cover s50b32 power ok.
If I have missed something ye might let me know thanks

[Jhonno]

I wouldn't fancy it, but in theory if you look at M20 turbo's it should be up to it..

[DanThe]

Apparently the S50 doesnt like the flywheel too light, so id keep it as close to standard as possible

[UweM3]

Apparently the S50 doesnt like the flywheel too light, so id keep it as close to standard as possible

On what is your statement based? Can you a bit more specific please. How light is too light?

[Jhonno]

It is the b32 that has potential issues.. Some are fine, some aren't, it is to do with the VANOS

My B30 is fine with it's one..

It's not just weight anyway.. It is where the weight is situated on the rotating mass of course

[DanThe]

Apparently the S50 doesnt like the flywheel too light, so id keep it as close to standard as possible

On what is your statement based? Can you a bit more specific please. How light is too light?

Just on what ive heard, alloy flywheels can be bad news to the B32's
I cant remember exactly as ive been to bed since

Germangorilla could probably tell you more as im sure he has encountered this with his car

[dicko]

Oh I dont like the sound of that
Good to find out now though.

[UweM3]

Oh I dont like the sound of that
Good to find out now though.

To find out what exaclty? (that's what I am trying to get to)

So far we have no real evidence of what flywheel is too light (or not?) for the S50B32.

All based on what someone else has said.

I still have the dual mass flywheel but was considering to change to a TTV steel flywheel.

The only downside of a very light flywheel I know off is the tendency to stall when one is a bit sloppy with the throttle when driving off. Or to spin the wheels if too keen. For a daily driver maybe not ideal, for a trackday car who cares.

The gearbox rattle which can sometimes occur is from the lighter flywheel not able to even out the firing order. Heavier helps in this matter.

[dicko]

To find out what exaclty? (that's what I am trying to get to)

So far we have no real evidence of what flywheel is too light (or not?) for the S50B32.

All based on what someone else has said.

I still have the dual mass flywheel but was considering to change to a TTV steel flywheel.

The only downside of a very light flywheel I know off is the tendency to stall when one is a bit sloppy with the throttle when driving off. Or to spin the wheels if too keen. For a daily driver maybe not ideal, for a trackday car who cares.

The gearbox rattle which can sometimes occur is from the lighter flywheel not able to even out the firing order. Heavier helps in this matter.[/quote]

I supose a m20 can hardly be disribed as light anyway .
as for stalling I wont be driving in traffic so that shouldnt be problem .
Is that ttv flywheel solid ?

[UweM3]

www.ttvracing.com

but be warned, they are very very slow....

[hoshy]

I'm interested in this too.
I've got a b32 and it feels a bit sluggish to rev. Pulls like a train though

[GermanGorilla]

Hi,

A lighter flywheel works well on the
S50 and the S54.

If you use an ALLOY flywheel with a solid
clutch disc then 'Gearbox Chatter' can be quite
loud for just road car use, other than that its fine.

Lightened Steel is much better and a lot less
chatter.

If you go to light on the flywheel /clutch
and are running the standard ECU's then
due to the engine spooling up much quicker
the ECU can become confused, which results
in poor running, and can also cause the
engine to stall on tickover when at correct
temps.

A good set up with 8-10lbs removed overall really
does make the car very nice across the rev range,
especially when used in conjunction with a good
SSK.

Regards.


The Gorilla.

[Jhonno]

I found the opposite..

I get MORE chatter with a billet steel flywheel, I had none with my old alloy one

[UweM3]

Hi,

If you go to light on the flywheel /clutch
and are running the standard ECU's then
due to the engine spooling up much quicker
the ECU can become confused, which results
in poor running, and can also cause the
engine to stall on tickover when at correct
temps.

The Gorilla.

Danny you have to explain that a little bit more to me. How can a ECU get "confused"? It's a computer in the end, nothing with own intelligence. There are parameters and routines, the only thing which may happen that it runs out of computing power. Don't think this is the case with the BMW ECU.

I am by no means a software or hardware developer, but taken your statement in I conclude that I need to be scared to drive downhill fast because the ECU may get confused from the engine spooling up quicker??

C'mon get the details out.

I can imagine that from reducing flywheel weight too much and as a result the engine not running "round" at idle the ECU is not fast enough (or maybe the ECU IS fast enough and it's the rest of the hardware, injectors, sensors etc) to compensate and as a result the idle gets rough. Do you know what I mean?
I.E. ECU senses idle too low (in the slow part of the "unroud" running idle) and raises the revs but the "normal" idle speed part of the unround cirlce is just going to happen and therefore the raise was too much so ECU lowers the idle speed right into the "slow" part of the unround running and so and on....

[Gunni]

The siemens on the B32 will not get confused.

What may happen is what Uwe mentioned.
But the siemens ECU as with all ecu´s since ´90 will be able to teach itself over time to compensate for this. I.e it´s subroutines will monitor possible changes that need to be done and then over the course of time it will get better.

[dicko]

I though these ecu,s were super fast so fast that they can detect which cylinder is misfiring ?

Anyway by the sound of all that it souldnt be a problem for me as the m20 flywheel is not that light and clutch disc is sprung.

[GermanGorilla]

Hi,

Guys, this is to do with the paramiters that
were set in the software when it was
originally written.

For sure the Siemmens ECU is very quick
and can decipher input signals very quickly.

However this was all worked out on the basis that
the engine rotating mass would be 'X' +/- in regard
of the weight of a dual mass flywheel.

When you map or write software for any engine
you have to have paramiters so that you know where
to set or bring in compensations etc.

Thus from say 1000 rpm it could only ever spool up
or down at a given rate, the original increasing and
reducing mass of the dual flywheel was factored in to these paramiters,
reduce the rotating mass and you increase the speed over the given paramiters.

You are not talking through the whole cycle.

It has nothing to do with the ECU's capability but the
paramiters of the software.

You can have the fastest computer in the world but
it is the software that is the limiting factor.

Yes the Siemmens MS S50/52 is 'adapative' to a point but this
is to do with the input signals from your driving
style it does not and can not alter the original set software paramiters
that the roating mass would be x at a given point.

Greater 'gearbox' chatter on a steel flywheel would
indicate that its not balanced corectly, or that its
clutch pressure plate has not been zero balanced with the
flywheel.

Regards,

The Gorilla.

[DanThe]

Greater 'gearbox' chatter on a steel flywheel would
indicate that its not balanced corectly, or that its
clutch pressure plate has not been zero balanced with the
flywheel.

I have experienced this myself, with a flywheel machined enough to miss the M50 sump/bolts (not balanced) I had a lot of gearbox chatter.
With my new lightened and fully balanced flywheel/clutch combo that weighs 11kg total there is no chatter at all

If I were you Jhonno id get that flywheel/clutch checked out