Crank Hub Issue Master Thread: What You Need To Know!

[Chase__M4]

Originally Posted by RevNev

That's anti-lag which the S55 engine doesn't have a lot turbo lag anyway. But I'm referring tuned burbles not stock burble. Tuned engines is where history tells us they're more susceptible to spinning the crank hub and if they're dumping fuel in and retarding the ignition to create more burbles, popping flames etc, that massively stresses the engine. It's the reason air bypass anti-lag systems were developed to minimised engine stress caused by the retarded ignition method. If you can snap a conrod with anti-lag, you'll spin a crank hub easily!

In my own SCH situation I was just trying to hear the burbles at like 4k... I let off and boom SCH, no hard kick downs or hard downshifts 4k was the highest. The SCH debate saga continues....

[mark5092]

Originally Posted by Chase__M4

In my own SCH situation I was just trying to hear the burbles at like 4k... I let off and boom SCH, no hard kick downs or hard downshifts 4k was the highest. The SCH debate saga continues....

Just glad it’s still not a common problem!!

[chetrickerman]

Originally Posted by RevNev

That's anti-lag which the S55 engine doesn't have a lot turbo lag anyway. But I'm referring tuned burbles not stock burble. Tuned engines is where history tells us they're more susceptible to spinning the crank hub and if they're dumping fuel in and retarding the ignition to create more burbles, popping flames etc, that massively stresses the engine. It's the reason air bypass anti-lag systems were developed to minimised engine stress caused by the retarded ignition method. If you can snap a conrod with anti-lag, you'll spin a crank hub easily!

Retarding the engine and dumping fuel does not stress the engine more, it stresses the turbo chargers and exhaust system more.

Think about it this way. When the DME wants to make less torque, for example, during a boost spike, to reduce torque, it opens the wastegates to vent the pressure. OR an even faster way to reduce the torque is to retard the timing. That reduces turbo lag by keeping the pressurized air in the system, that way if the DME needs it, the air is there.

Retarding the ignition timing reduces the torque directly, and if you retard it enough, the combustion process can actually take place outside of the combustion chamber, and inside the exhaust manifold. That spools up the turbos very quickly, and produces the loud pops and bangs, but its very harsh on the turbine wheel.

[RevNev]

Originally Posted by chetrickerman

Retarding the engine and dumping fuel does not stress the engine more, it stresses the turbo chargers and exhaust system more.

Think about it this way. When the DME wants to make less torque, for example, during a boost spike, to reduce torque, it opens the wastegates to vent the pressure. OR an even faster way to reduce the torque is to retard the timing. That reduces turbo lag by keeping the pressurized air in the system, that way if the DME needs it, the air is there.

Retarding the ignition timing reduces the torque directly, and if you retard it enough, the combustion process can actually take place outside of the combustion chamber, and inside the exhaust manifold. That spools up the turbos very quickly, and produces the loud pops and bangs, but its very harsh on the turbine wheel.

No that's wrong. Talk to the rally guys who blew engines with anti-lag and ask them why they developed air bypass anti-lag systems instead. Igniting the fuel well after TDC on the power stroke results in maximum cylinder pressure on the exhaust stroke when the valve train is attempting to open the exhaust valves. That additional pressure is what keeps the turbos spooled up and most definitely will increase the force applied to the crank hub to open the exhaust valves against abnormal combustion pressure. With no anti-lag (burbles) on overrun hence minimal pressure, the turbos slow down don't they?

Basically, additional forces beyond the capabilities of the friction washer setup is causing the crank hub to spin. Interestingly, does the GT4 race car burble on overrun and the video's I've heard, they don't seem to burble at all or not excessively to notice it.

[RevNev]

Originally Posted by Chase__M4

In my own SCH situation I was just trying to hear the burbles at like 4k... I let off and boom SCH, no hard kick downs or hard downshifts 4k was the highest. The SCH debate saga continues....

A few have reported hub spins on deceleration and that's nothing to do with making power. What's loading the valve train on overrun and burbles will if they're achieved by retarded spark. Max burble tune ups if they're adding more fuel and retarding the spark more to make them crackle hard on overrun isn't reducing valve train load.

How many have spun crank hubs on a stage 2 tune with burbles disabled is the question to answer

Maybe it's not the kickdown spinning the hub, it spins when they get off the throttle at high revs after the kickdown? When does it go into limp mode from a spun hub, immediately on kickdown and the engine won't rev, or after it's hit the rev limiter?

[Demxsr]

Originally Posted by chetrickerman

Retarding the engine and dumping fuel does not stress the engine more, it stresses the turbo chargers and exhaust system more.

Think about it this way. When the DME wants to make less torque, for example, during a boost spike, to reduce torque, it opens the wastegates to vent the pressure. OR an even faster way to reduce the torque is to retard the timing. That reduces turbo lag by keeping the pressurized air in the system, that way if the DME needs it, the air is there.

Retarding the ignition timing reduces the torque directly, and if you retard it enough, the combustion process can actually take place outside of the combustion chamber, and inside the exhaust manifold. That spools up the turbos very quickly, and produces the loud pops and bangs, but its very harsh on the turbine wheel.

What is your opinion on what is causing the timing sprocket to slip then? In the case of the bolt itself not coming loose. I'm in no way questioning your comment on burbles, because you for sure know way more than I do on the topic.

[chetrickerman]

Originally Posted by RevNev

No that's wrong. Talk to the rally guys who blew engines with anti-lag and ask them why they developed air bypass anti-lag systems instead. Igniting the fuel well after TDC on the power stroke results in maximum cylinder pressure on the exhaust stroke when the valve train is attempting to open the exhaust valves. That additional pressure is what keeps the turbos spooled up and most definitely will increase the force applied to the crank hub to open the exhaust valves against abnormal combustion pressure. With no anti-lag (burbles) on overrun hence minimal pressure, the turbos slow down don't they?

Basically, additional forces beyond the capabilities of the friction washer setup is causing the crank hub to spin. Interestingly, does the GT4 race car burble on overrun and the video's I've heard, they don't seem to burble at all or not excessively to notice it.

1. Rally guys have issues with blowing TURBOS, not engines from anti-lag, I have tuned rally cars...... Evo's specifically. Thats why with most anti-lag systems manufacturers warn against using it excessively since its very harsh on the turbine wheel.

2. When the exhaust valves open, there is not nearly the amount of pressure you think there is, because the combustion chamber size has increased as the piston is at BDC.
Yes igniting the air/fuel mixture well after TDC does produce some pressure that the exhaust valves have to overcome when opening, but its not even close to the amount of pressure produced during normal combustion with the ignition at the proper angle, HENCE why torque is reduced when ignition timing is retarded. Im not sure if you read my post entirely, but I said retarding the ignition advance enough can actually make combustion take place outside the combustion chamber, which does spool the turbos very quickly, but it doesnt produce much power.

3. I am talking about how the burbles are produced in the S55, as well as how many anti-lag (not air bypass) systems operate. You are welcome to think what you want, but I tune S55's and B58's, I know exactly how the burbles work.

A possible reason the GT4 race car doesnt have issues with spinning the hub is because they are usually tuned to have a more linear power band, rather than tons of torque down low. Their engines are likely rebuilt far more often then our road cars as well.

Originally Posted by Demxsr

What is your opinion on what is causing the timing sprocket to slip then? In the case of the bolt itself not coming loose. I'm in no way questioning your comment on burbles, because you for sure know way more than I do on the topic.

The cams have resistance to movement. As speed and power increases, so does that resistance. Valve springs, and a good amount of friction is produced in the valve train.

I have yet to see a crank hub spin without the central bolt coming loose first. Many of my clients/friends run just a crank hub bolt capture and they have been running 700+ whp for years without issue.

[RevNev]

Originally Posted by chetrickerman

1. Rally guys have issues with blowing TURBOS, not engines from anti-lag, I have tuned rally cars...... Evo's specifically. Thats why with most anti-lag systems manufacturers warn against using it excessively since its very harsh on the turbine wheel.

2. When the exhaust valves open, there is not nearly the amount of pressure you think there is, because the combustion chamber size has increased as the piston is at BDC.
Yes igniting the air/fuel mixture well after TDC does produce some pressure that the exhaust valves have to overcome when opening, but its not even close to the amount of pressure produced during normal combustion with the ignition at the proper angle, HENCE why torque is reduced when ignition timing is retarded. Im not sure if you read my post entirely, but I said retarding the ignition advance enough can actually make combustion take place outside the combustion chamber, which does spool the turbos very quickly, but it doesnt produce much power.

3. I am talking about how the burbles are produced in the S55, as well as how many anti-lag (not air bypass) systems operate. You are welcome to think what you want, but I tune S55's and B58's, I know exactly how the burbles work.

A possible reason the GT4 race car doesnt have issues with spinning the hub is because they are usually tuned to have a more linear power band, rather than tons of torque down low. Their engines are likely rebuilt far more often then our road cars as well.



The cams have resistance to movement. As speed and power increases, so does that resistance. Valve springs, and a good amount of friction is produced in the valve train.

I have yet to see a crank hub spin without the central bolt coming loose first. Many of my clients/friends run just a crank hub bolt capture and they have been running 700+ whp for years without issue.

Okay, I disagree with your opinion from my motorsport experience that began in 1977 and consequently disabled burbles in my tune up to minimise stress. The S55 engine doesn't need anti-lag (burbles)as they struggle enough to manage wheel spin on corner exit in stock trim.

[Twistm4]

Sorry I have to chime in here as well. The notion that slight timing retardation to produce a very minimal overlay of combustion into the exhaust manifold is contributing to stress on the hub is misguided. That's just not how that works. Also, we are talking very , VERY minimal burbles as compared to some other platforms/tunes. It's not even enough to create an anti-lag feature (the principal is the same), so thinking it's somehow causing stress on that component just doesnt make sense, mechanically speaking.

With that being said, this feature can cause issues with turbo longetivity, o2 sensors and catalytic converters, due to the increased pressure and heat. However that doesn't seem to be the case on this platform. I think burbles are stupid and childish on most platforms. And i think there probably is a correlation between those that try to abuse burble features to show off to their friends, and spun crank hubs. They tend to be privy to the type of driving habits that are constantly de revving high gears in peak torque to show off the pops, but it's not the tuning causing issue.

That's why I love the handheld tuners we have, I can set exactly the rpm, duration and volume of the pops and it works beautifully. I have it on the softest setting for .5 seconds after 2400 rpm, and I would bet my car and left arm the engine doesn't even notice it's there over the course of years and years. I also will add I have never had an issue with just the bolt capture after 100+ drag passes , launches, hundreds of roll races, daily abuse and a whole lot of fun!

[cheveux]

Originally Posted by Chase__M4

In my own SCH situation I was just trying to hear the burbles at like 4k... I let off and boom SCH, no hard kick downs or hard downshifts 4k was the highest. The SCH debate saga continues....

has i wrote somewere on this forum, the main cause of the sch is the suddent change of torque/rpm.

if you are going 4000rpm and left off, or kickdown, or suddent accelerations (harder with e85), my opinion is that the timming chain (connected to the hub) loosens the central screw by turning faster and suddenly than the oil pump chain. I really think the problem is 90% loosen central screw and 10% the friction disc

[deeldoo]

Originally Posted by cheveux

has i wrote somewere on this forum, the main cause of the sch is the suddent change of torque/rpm.

if you are going 4000rpm and left off, or kickdown, or suddent accelerations (harder with e85), my opinion is that the timming chain (connected to the hub) loosens the central screw by turning faster and suddenly than the oil pump chain. I really think the problem is 90% loosen central screw and 10% the friction disc

And this is why in Europe all they do is the crank bolt capture.

I havent even heard of an F8x going kaboom because of the friction discs. The bolt always backs out first.

[Demxsr]

Originally Posted by chetrickerman

I have yet to see a crank hub spin without the central bolt coming loose first. Many of my clients/friends run just a crank hub bolt capture and they have been running 700+ whp for years without issue.

This is really good to know. Thanks for the info.

[Demxsr]

Originally Posted by Twistm4

That's why I love the handheld tuners we have, I can set exactly the rpm, duration and volume of the pops and it works beautifully. I have it on the softest setting for .5 seconds after 2400 rpm, and I would bet my car and left arm the engine doesn't even notice it's there over the course of years and years. I also will add I have never had an issue with just the bolt capture after 100+ drag passes , launches, hundreds of roll races, daily abuse and a whole lot of fun!

What tune are you using that gives you that control over the pops?

[Twistm4]

Originally Posted by Demxsr

What tune are you using that gives you that control over the pops?

MHD

[mp335]

Sharing some thoughts for anyone looking to get used f80 m3. I gone through research. Most important thing to understand is CH issue is not a fluke it's real. It happened on 10+ cars across all production years. It is design flaw. As with any mechanical component under stress single weakness over time can destroy anything. As more cars put miles and come out of warranty these issues will keep happening. From my understanding no car is safe it happens on stick/tuned/low miles etc. I noticed that there are no CPO m3s in my area, there are so many low miles cars sold by good BMW dealers but not cpo. That clearly tells they know something that probably normal buyer doesn't. Long story short I will put my money on s58 looks very promising.

[LATTES]

Originally Posted by mp335

Sharing some thoughts for anyone looking to get used f80 m3. I gone through research. Most important thing to understand is CH issue is not a fluke it's real. It happened on 10+ cars across all production years. It is design flaw. As with any mechanical component under stress single weakness over time can destroy anything. As more cars put miles and come out of warranty these issues will keep happening. From my understanding no car is safe it happens on stick/tuned/low miles etc. I noticed that there are no CPO m3s in my area, there are so many low miles cars sold by good BMW dealers but not cpo. That clearly tells they know something that probably normal buyer doesn't. Long story short I will put my money on s58 looks very promising.

What's the point here? I got my cpo, but what you mentioned makes some sense. For new engine, never know if it's bulletproof from factory or not, I doubt it wouldn't..

[mp335]

Originally Posted by LATTES

What's the point here? I got my cpo, but what you mentioned makes some sense. For new engine, never know if it's bulletproof from factory or not, I doubt it wouldn't..

No specific point just frustration that car I really wanted is so stupidly flawed
And brand that I always admired is not living up. Also just wanted to share thoughts for anyone looking to buy used. S55 is not a new engine..n54 was the beginning then n55 then S55. It is just amazing how BMW screwed up this motor. Stock cars with 30k miles should never have such issue..not acceptable by any standards..inline 6 making 420hp not a rocket science 2.0l are making more power reliably(not blowing engine).
I owned N54 and tuned he'll out of it..i never worried about blowing that motor during pulls..it had its flaws but nothing that would discourage one from driving hard. Anyhow this chapter is closed.

[MasterYous]

Thinking the S55 is a screwed up motor is a matter of opinion. I have owned N55, S55, B58 and S58 and the S55 is by far my favorite:
- turbo lag is short and manageable - and when you add a decent tune and proper bolt-ons it's practically gone
- redundancy everywhere - cooling, intakes, fueling, turbos, etc
- it can take a beating. Track any of the other engines regularly and you'll see the S55 was meant to be abused (SCH issue aside, which is a sad situation- but there is an affordable fix out there as we all know)
- smoothness - for a forced-induction motor it's incredibly refined - moreso than the B58 which I drove for 3+ years and the S58 which I drove for 6 months
- headroom for tunes - people are pushing 550+ wheel with basic bolt-ons in some cases - Full E85 (thanks to the dual fuel pumps) and a good tune (and the SCH fix) and you're flying. That's impressive...

Full story is not yet written about S58 since it's still new and further revisions may make it surpass the S55 in every way, but not quite there yet. For now it has some of the IAT issues that hurt the B58, robbing power after heavy use; and its turbo lag is noticeably worse than the S55. IMO the S55 was a huge leap forward for track-quality turbocharged engines and let's see how easy it is for BMW to make us forget about it.

[elinstylez]

Any confirmed cases of SCH with just the CBC? I still haven't seen one so far that's not due to driver error.

[mp335]

Originally Posted by elinstylez

Any confirmed cases of SCH with just the CBC? I still haven't seen one so far that's not due to driver error.

Yes there are reported issues even on stock car with 4k rpm.

[elinstylez]

Originally Posted by mp335

Yes there are reported issues even on stock car with 4k rpm.

Can you provide the link? The only one I saw was the guy who money shifted.

[CT_M3]

Originally Posted by mp335

No specific point just frustration that car I really wanted is so stupidly flawed
And brand that I always admired is not living up. Also just wanted to share thoughts for anyone looking to buy used. S55 is not a new engine..n54 was the beginning then n55 then S55. It is just amazing how BMW screwed up this motor. Stock cars with 30k miles should never have such issue..not acceptable by any standards..inline 6 making 420hp not a rocket science 2.0l are making more power reliably(not blowing engine).
I owned N54 and tuned he'll out of it..i never worried about blowing that motor during pulls..it had its flaws but nothing that would discourage one from driving hard. Anyhow this chapter is closed.

If you search for the SCH poll conducted on this forum, based on the responses, the occurrence of a SCH is very very low (<3%) I believe on the stock cars. Even up to 550WHP it’s a small subset. At >550WHP, E85, it gets much higher.

Keep in mind, this is an enthusiast forum and people here run their cars harder than the general population and are more likely to complain.

I remember the days when the E46 S54 was such a big deal. NA with more than 100 hp/l. Just keep in mind that getting 500+ in 3L is pretty amazing.