Maximum PSI F8X M3 updates – keyed crank hub in testing!

We decided to purchase a F80 M3 for our latest shop car in late 2015. The S55 motor found in the new M3 and M4 is an awesome powerplant, and we fell in love with the new body style.  We quickly developed multiple bolt-on parts for this platform including front-mounted intakes, silicone charge pipes, and downpipes.  The car went from stock to full bolt-ons including turbo upgrades and fuel system changes in a short period of time.  We quickly jumped into the #1 drag racing spot with a 10.2@137mph in the 1/4 mile.  Everything was great.  We made some additional changes, and then our M3 suffered from a spun crank hub.  This happened with only ~3000 miles on the car.  We quickly discovered most of the exhaust valves were bent, and we pulled the motor and put the car on the back burner.   TPG tuning was another vendor that had experienced this failure early on, and while they tried to come up with a solution for their car and customers, there were some failures with some of their earlier hub solution attempts.  The BMW forums went on a witch hunt trying to accuse TPG of selling parts for a failure that didn’t exist, and a lot of drama popped up on multiple sites.  I understand the frustration of customers that purchased an upgraded part that still failed, but TPG was only trying to offer the community a solution to a problem that is very real.  To anyone unfamiliar with the S55 timing gear/crank hub design you can read up by clicking here.

We eventually got the car back together with upgraded rods and pistons, and we installed an aftermarket crank hub from another vendor.  It had a different bolt, and combined the hub and the first timing gear into a single part.  It still used the stock oil pump gear.  We hoped that it would fix the issue, however we knew there was a good chance it would spin again due to the lack of any sort of pin or keyway.   We rushed to get the motor and car assembled, and we took it to MPACT east in July 2016.  The car only made it about 5 passes before the hub spun again during a burnout before a 1/2 mile run.  This time we were lucky as there was no piston to valve contact.  We once again put the car to the side and dealt with our shop move to our current new facility in South Amboy, NJ.  At that point we decided to focus on making a new crank hub and gear design.  There were multiple design constraints, including assembly process, existing crankshaft snout design, and cost.  A new crankshaft with integrated gears would be my first choice, but it would be extremely expensive and would require a complete teardown of the engine and would be very annoying to assemble the chains since everything is one piece.  We opted for a design that had an interlocking crank hub, timing gear, and oil pump gear.  The three parts all lock together with beefy keyways, and the gears are new units made by us.  The tricky part was coming up with a design that was also keyed to the end of the crank, and we tackled that with a drill fixture and hardened pins.  The install requires dropping the oil pan and removing the timing components.  To anyone that is interested in our crank hub solution, please email us at sales@maximumpsi.com to be put on a contact list.

We got our F80 M3 back together the week before MPACT 2017 with our keyed hub along with some more upgrades.  The car worked flawlessly on pump gas at MPACT, and we put it back on E85 after the event.  Since then we have been to the drag strip for two test days, and have made 5 10 second passes, including our new record of 10.1@139mph.  We will continue to romp on the car and try and put the components to the test.  We want to get some more time on our car and two other cars before making a larger second batch of gears, but the first test days were positive!  We look forward to pushing the platform further instead of worrying if the next drag pass is going to result in pulling the motor apart to rebuild or retime.

– Mike and the Maximum PSI team

 

 

 

 

 

 

 

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