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Our F80 M3 crank hub held up through, Stage 1, Stage 2, and Stage 2+ where it was making 543whp/547wtq using an OTS tune and our S55 FBO Kit.  These were approximately 7k HARD miles without any issues.  It did eventually fail on our 100% E85 custom tune from Cary Jordan.  Cary warned us that there was a strong chance the crank hub would fail at the 100% E85 power levels, but we've made it this far without one and wanted to take our chances to see what happened.  This is what happened...

S55 Crank Hub

When the crank hub failed, it was much less eventful than you would expect.  We were cruising a long on the highway at steady speed when the CEL light appeared.  Nothing uncommon when you're driving a tuned BMW!  We chalked it up to an emissions sensor, overboost, or the like, expecting it to turn off after parking and returning to the car.  However, the light was still on after restarting the car.  After pulling the codes we saw the following unique codes appear: 

130E20: Angle deviation with respect to crankshaft outside tolerance

130F20: Exhaust Camshaft: Offset angle to cranksahft outside tolerance

120408: Charging pressure control deactivation: pressure build-up blocked

Learning that these were the codes for a spun crank hub, we begun the process of sourcing a Crank Hub Fix.  We ended up getting the MaxPSI Crank Hub Fix for our F80.

S55 Crank Hub

After pulling the engine we were lucky enough to find out that we did not have any valves bent.  Which meant that we were able to reassemble the engine, recalibrate the timing, and install our crank hub fix as if it had never spun at all.  However, many others have not been so lucky. If your valves are bent you will of course have the cost of the valves themselves and the labor to install them.  Regardless of whether your valves do bend or not, an engine-out service is required, and at the minimum you are looking at 20 hours of labor!

S55 crank hub

The CHF that we used was a keyed crank hub that required drilling.  The drilling took A LOT of time, 7 carbide drill bits worth of time.  But now that's it's done, our S55's crank hub is rock-solid and we're able to push the S55 to the next limit which will be the turbos!  You can read up on our final E85 custom tune numbers and results HERE

S55 Crank Hub

Having gone through this process, we strongly recommend a keyed crank hub if you plan on tuning your S55 BMW.  Especially if you plan on running an E85 blend tune, because the advanced timing creates a good bump in power and torque above and beyond a basic Stage 1 tune which is the true cause of the spun crank hub.  Should you go for a full custom tune we highly recommend Cary Jordan, he is first class tuner in terms of communication, safety, and results.  For some of the best hardware upgrades for your S55 BMW CLICK HERE!

If you need help or advice with your S55-powered BMW, let us know!  Our team of experts is happy to assist you with you build. 

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