M3/M4 Bedplate Update?

[YasM4]

I was wondering if there has been any additional information released or leaked with regard to the Bedplate update in the 4 quarter of 2015.

Was this intended to be a fix to help resolve the spun crank issue? Is the S55 with the old bedplate design significantly inferior?


Thank you for the info in advance.

[CaryTheLabelGuy]

Originally Posted by YasM4

I was wondering if there has been any additional information released or leaked with regard to the Bedplate update in the 4 quarter of 2015.

Was this intended to be a fix to help resolve the spun crank issue? Is the S55 with the old bedplate design significantly inferior?


Thank you for the info in advance.

We don't know a whole bunch about the new bedplate but we we do know is there was a bedplate change and resulting PN change in Dec of 2015. The ZCP/GTS (Competition Engine) literature touts the new bedplate as being strengthened for the increased power of the ZCP/GTS. However, the new PN carried over to the non-ZCP/GTS S55 engines as well and was a quiet change from BMW - they made no mention of it for the non-ZCP/GTS S55's. The question is, how long did BMW continue to use the old design on the non-ZCP/GTS engines and how many older engines were left over after the switch.

What I personally believe: The new bedplate design was to help mitigate the crank hub issues by better bracing the crankshaft. It's rather obvious to me that the crankshaft was experiencing a problematic harmonic imbalance and certainly had crank twisting which is very common on inline 6 engines as they have long cranks. These two issues were probably what was causing the crank hub/timing sprockets to slip. By improving the bedplate design (which its only job is hold/brace the crank), you can decrease the likelihood of harmonic issues and possibly alter crank twist.

[YasM4]

Originally Posted by CaryTheLabelGuy

We don't know a whole bunch about the new bedplate but we we do know is there was a bedplate change and resulting PN change in Dec of 2015. The ZCP/GTS (Competition Engine) literature touts the new bedplate as being strengthened for the increased power of the ZCP/GTS. However, the new PN carried over to the non-ZCP/GTS S55 engines as well and was a quiet change from BMW - they made no mention of it for the non-ZCP/GTS S55's. The question is, how long did BMW continue to use the old design on the non-ZCP/GTS engines and how many older engines were left over after the switch.

What I personally believe: The new bedplate design was to help mitigate the crank hub issues by better bracing the crankshaft. It's rather obvious to me that the crankshaft was experiencing a problematic harmonic imbalance and certainly had crank twisting which is very common on inline 6 engines as they have long cranks. These two issues were probably what was causing the crank hub/timing sprockets to slip. By improving the bedplate design (which its only job is hold/brace the crank), you can decrease the likelihood of harmonic issues and possibly alter crank twist.

Originally Posted by CaryTheLabelGuy

We don't know a whole bunch about the new bedplate but we we do know is there was a bedplate change and resulting PN change in Dec of 2015. The ZCP/GTS (Competition Engine) literature touts the new bedplate as being strengthened for the increased power of the ZCP/GTS. However, the new PN carried over to the non-ZCP/GTS S55 engines as well and was a quiet change from BMW - they made no mention of it for the non-ZCP/GTS S55's. The question is, how long did BMW continue to use the old design on the non-ZCP/GTS engines and how many older engines were left over after the switch.

What I personally believe: The new bedplate design was to help mitigate the crank hub issues by better bracing the crankshaft. It's rather obvious to me that the crankshaft was experiencing a problematic harmonic imbalance and certainly had crank twisting which is very common on inline 6 engines as they have long cranks. These two issues were probably what was causing the crank hub/timing sprockets to slip. By improving the bedplate design (which its only job is hold/brace the crank), you can decrease the likelihood of harmonic issues and possibly alter crank twist.

Thank you for the update!

I took delivery in December but my build date was November, so I have the old design. Not to happy about that. I guess we can only speculate. Very disappointed.

[CaryTheLabelGuy]

Originally Posted by YasM4

Thank you for the update!

I took delivery in December but my build date was November, so I have the old design. Not to happy about that. I guess we can only speculate. Very disappointed.

Yes, that's unfortunate. However, I doubt you'll have any issues. The older S55's are still very stout and there are plenty of them out there doing just fine.

[schnell1982]

Originally Posted by YasM4

Thank you for the update!

I took delivery in December but my build date was November, so I have the old design. Not to happy about that. I guess we can only speculate. Very disappointed.

There are a lot of S55's that have not experienced 1 failure on the 1st year production of engines.
Modified parts can increase your risk of slippage.
Thankfully there is the added help / information of this specific forum members opening up about their experiences.
Its nice to know that there are some product part number revisions.

2 known updates are that BMW did increase the torque spec of the front crank bolt and the washer between the hub was also updated to a version with a more abrasive face. Basically its not smooth anymore and the redesign creates more "bite".

Other then those updated parts and new part numbers...its a matter of time to see if anyone reports any issues

[YasM4]

Originally Posted by schnell1982

There are a lot of S55's that have not experienced 1 failure on the 1st year production of engines.
Modified parts can increase your risk of slippage.
Thankfully there is the added help / information of this specific forum members opening up about their experiences.
Its nice to know that there are some product part number revisions.

2 known updates are that BMW did increase the torque spec of the front crank bolt and the washer between the hub was also updated to a version with a more abrasive face. Basically its not smooth anymore and the redesign creates more "bite".

Other then those updated parts and new part numbers...its a matter of time to see if anyone reports any issues

Thank you for the encouragement!

[CanAutM3]

Originally Posted by CaryTheLabelGuy

We don't know a whole bunch about the new bedplate but we we do know is there was a bedplate change and resulting PN change in Dec of 2015. The ZCP/GTS (Competition Engine) literature touts the new bedplate as being strengthened for the increased power of the ZCP/GTS. However, the new PN carried over to the non-ZCP/GTS S55 engines as well and was a quiet change from BMW - they made no mention of it for the non-ZCP/GTS S55's. The question is, how long did BMW continue to use the old design on the non-ZCP/GTS engines and how many older engines were left over after the switch.

What I personally believe: The new bedplate design was to help mitigate the crank hub issues by better bracing the crankshaft. It's rather obvious to me that the crankshaft was experiencing a problematic harmonic imbalance and certainly had crank twisting which is very common on inline 6 engines as they have long cranks. These two issues were probably what was causing the crank hub/timing sprockets to slip. By improving the bedplate design (which its only job is hold/brace the crank), you can decrease the likelihood of harmonic issues and possibly alter crank twist.

Reading this got me thinking that maybe the move away from the magnesium oil sump is also related (potentially to increase the bottom end rigidity).

[DavidGP]

Was there not a forum member with a post December 2015 build that recently spun crank. I believe it was a 6 spd also. That would debunk the theory of the new bedplate as fix for the crank hub issue.

[CaryTheLabelGuy]

Originally Posted by DavidGP

Was there not a forum member with a post December 2015 build that recently spun crank. I believe it was a 6 spd also. That would bunk the theory of the new bedplate as fix for the crank hub issue.

Yes, but again, does this engine have the new bedplate? This wasn't a ZCP, it was a non-ZCP.

We don't really know and this is currently the only documented instance of a SCH in a post-Dec 2015 S55 that I'm aware of.

[CaryTheLabelGuy]

Originally Posted by CanAutM3

Reading this got me thinking that maybe the move away from the magnesium oil sump is also related (potentially to increase the bottom end rigidity).

Very possible. Magnesium isn't very strong and is pretty brittle when twisted/bent. You might be on to something.

[The Choosey begger]

Originally Posted by CanAutM3

Reading this got me thinking that maybe the move away from the magnesium oil sump is also related (potentially to increase the bottom end rigidity).

You dont use an oil pan to reinforce the bottom end, probably has to do with cost.
Some engines that produce well over 1,500 lb-ft torque use Kevlar oil pans.

[The Choosey begger]

Originally Posted by CaryTheLabelGuy

Very possible. Magnesium isn't very strong and is pretty brittle when twisted/bent. You might be on to something.

Magnesium can be stronger than aluminum with better heat dissipation properties and lighter.

[4everkidd]

Originally Posted by CaryTheLabelGuy

Very possible. Magnesium isn't very strong and is pretty brittle when twisted/bent. You might be on to something.

Originally Posted by anglo

Magnesium can be stronger than aluminum with better heat dissipation properties and lighter.

This is a tough one... Mg by volume is actually quite strong; obviously not as strong as steel but 75% lighter in the same volume.

Mg isn't cheap, however the manufacturing process with Mg cast's is simpler as its an easier metal to work with. More expensive material, with decreased manufacturing costs.

As far as impact strength is concerned, Mg can't go toe to toe with stainless. That could also be cause for the change of PN and materials for the oilpan.

Tensile Modulus (Young's) and weight advantage for comparison:

Mg 6.4E+6 psi
Al 10E+6 psi --> Mg ~35% lighter
Ti 16E+6 psi --> Mg ~50% lighter
Stainless (304) 28E+6 --> Mg ~75% lighter

[CanAutM3]

Originally Posted by anglo

Magnesium can be stronger than aluminum with better heat dissipation properties and lighter.

Are you sure about this . Quick Google search (Al / Mg):

[The Choosey begger]

Originally Posted by CanAutM3

Are you sure about this . Quick Google search (Al / Mg):

The new Z06 uses a Magnesium engine cradle, also Magnesium roof.

[CanAutM3]

Originally Posted by anglo

The new Z06 uses a Magnesium engine cradle, also Magnesium roof.

Still, despite being 33% heavier than Mg, Al is still 55~70% stiffer, so it is remains stiffer for the same weight.

Further, the F8X oil pan increased weight by ~45% with the switch in material, that means that, if they used Al, it is significantly stiffer than the old Mg one.

[The Choosey begger]

Originally Posted by CanAutM3

Still, despite being 33% heavier than Mg, Al is 55% stiffer, so it is still stiffer for the same weight.

Further, the F8X oil pan increased weight by ~45% with the switch in material, that means that, if they used Al, it is significantly stiffer than the old Mg one.

I doubt the new oil pan is to prevent SCH failures, that's laughable.
Some engines that produce more torque than the s55 have kevlar oil pans.

You dont know which Al or Mg alloy they used and then reached the conclusion that the new oil pan is significantly stronger.
You have to run tests to determine which is stronger, not out of thin air. You're probably a metallurgy expert too.

You wouldn't have airliners's magnesium wheels for high stress applications.

[CanAutM3]

Originally Posted by anglo

I doubt the new oil pan is to prevent SCH failures, that's laughable.
Some engines that produce more torque than the s55 have kevlar oil pans.

You dont know which Al or Mg alloy they used and then reached the conclusion that the new oil pan is significantly stronger.
You have to run tests to determine which is stronger, not out of thin air. You're probably a metallurgy expert too.

You wouldn't have airliners's magnesium wheels for high stress applications.

My point about the oil pan is pure speculation and only meant as an observation. Nothing more nothing less.

You however made false/misleading statements about the properties of magnesium.

As far as an oil pan being a structural element, it all depends on the overall design of the engine.

And no, I am not a metallurgical expert at all. We have many metallurgical specialists/engineers where I work. I rely on them.

[The Choosey begger]

Originally Posted by CanAutM3

My point about the oil pan is pure speculation and only meant as an observation. Nothing more nothing less.

You however made false/misleading statements about the properties of magnesium.

As far as an oil pan being a structural element, it all depends on the overall design of the engine.

And no, I am not a metallurgical expert at all. We have many metallurgical specialists/engineers where I work. I rely on them.

So you consulted with the metallurgy's expert at work and they told you the new aluminum oil pan is significantly stronger than the old magnesium one.

ok then.

That's purely speculative too.

[4everkidd]

Originally Posted by CanAutM3

Still, despite being 33% heavier than Mg, Al is still 55~70% stiffer, so it is remains stiffer for the same weight.

Further, the F8X oil pan increased weight by ~45% with the switch in material, that means that, if they used Al, it is significantly stiffer than the old Mg one.

That's why the strength is based on volume and not weight.

[The Choosey begger]

Originally Posted by 4everkidd

That's why the strength is based on volume and not weight.

It's a strength to weight ratio.

A Magnesium part that weighs 40% less than an Aluminum part may have the same strength.
That's why for example you have magnesium wheels on Ferrari Scuderias, not Aluminum wheels.
Or a magnesium Subframe on the Z06 and an Aluminum one on the regular Corvette.

My point was both the new and old oil pan will be close in strength even with the difference in weight.

[CanAutM3]

Originally Posted by anglo

It's a strength to weight ratio.

A Magnesium part that weighs 40% less than an Aluminum part may have the same strength.
That's why for example you have magnesium wheels on Ferrari Scuderias, not Aluminum wheels.
Or a magnesium Subframe on the Z06 and an Aluminum one on the regular Corvette.

My point was both the new and old oil pan will be close in strength even with the difference in weight.

OK, that one you will have to explain to me:

If both parts are dimensionally almost identical, the one made of aluminium is ~50% heavier than the magnesium one and aluminium is 55~70% stiffer than magnesium, how can you conclude that they have the same stiffness ?

BTW, we are talking stiffness here (resistance to elastic deformation), not yield strength (point of plastic deformation).

Choice of material depends on many factors depending on the application and what characteristic needs to be favoured. Weight vs volume is one of the tradeoffs. If the volume cannot be reduced, a material of lesser density can be used to favour weight if it is strong enough for the application. Or the other way around, if volume cannot be increased, a stronger material may need to be used. BTW, why do you think landing gears are made out of steel?

Again, I am in no way unequivocally saying that they changed material of the oil sump to make stiffer. But I think you are getting ahead of yourself with conclusions here.