How we turned our broken high mileage BMW F80 M3 into a track monster!

The F8X generation BMW M3 & M4 is getting on a bit in age & with age, has come depreciation. If you open up AutoTrader, you can find many high-mileage examples at very attractive prices but you don’t dare pull the trigger because of the thrashed drivetrain & deferred maintenance that lay behind the low price tag.

It’s a shame because these S55-powered BMWs have the potential to be very reliable when looked after & maintained thoroughly. We put together a reliability guide for the S55 engine here in case you are curious: https://r44performance.com/blogs/r44...ance-servicing

You see an F80 M3 with 120,000 miles on the clock for under $30,000 and already start imagining the thousands of dollars leaving your pocket to get it up to scratch.

However, when we saw our 2014 F80 M3 for sale at only £20,000 ($25,000), the only thing we thought was… yes please. What could go wrong? Well, quite a lot it turns out.

Straight after collection our director, Rhys, took the car on the NC500 - a 500-mile road trip around the north coast of Scotland, here in the UK. The car made the trip absolutely fine and we thought we had bought a gem. As we planned to do some development with this car, we got to work on the maintenance & installed an MMR crank hub kit. We’ve supplied many of these kits & haven’t heard a single customer car spinning the hub. Although a spun crank hub has affected less than 5% of S55 engines worldwide, we wanted to be on the safe side & get it sorted before any tuning began.

Unfortunately, shortly after installing this upgrade, the charge cooler let go. The engine ingested some water which caused a lot of internal damage. We needed a whole new S55 engine. This is why we always recommend replacing the cheap plastic OEM charge cooler with a higher-quality aftermarket item. We now run the CSF S55 charge cooler which is billet aluminium - not only is this far more reliable but it also improves cooling massively.

Our good friend Tom (the man behind our 1000bhp G80 M3) fortunately had a low mileage S55 doner engine from an F87 M2 Competition. He swapped the crank hub over & dropped the new engine in for us along with a DCT service & replacement flywheel.

This was quite a significant expense & completely wiped out the savings we’d made by buying a higher mileage example. 80,000 miles didn’t seem too high to us but it’s obvious the car had seen some pretty hard use & was very tired overall.

With a new low-mileage motor now in the car, we made a start on the performance upgrades.

In terms of bolt-ons, the car’s running the full CSF cooling package, including the heat exchanger, charge cooler, DCT oil cooler & engine oil cooler. We’re running an Active Autowerke equal-length midpipe which sounds incredible. The sound difference with an equal length on the S55 is crazy - far more high-pitched & less rasp. This is paired up with catless downpipes which provide the flow we needed for the Tom Wrigley 700 hybrid turbos.

The car runs around 650 bhp at the crank - all the power we need for a track car. Tom Wrigley Performance took care of all the software using MHD.

With the engine & drivetrain now 10/10, the track mods began. We threw away the OEM discs & pads for the EBC 2-piece floating brake discs all around & EBC RP-X pads. These pads are only for track use - perfect for what we were after.

The next stage of the project was to install Nitron R3 coilover suspension, an SW Motorsports half roll cage, 2x Tillett carbon fibre racing seats, Schroth harnesses, a SHFT LED steering wheel in carbon fibre & Alcantara + the new MHC LDN pre-preg carbon styling kit.

What’s the catch? We only had 4 hours until the car was due to be showcased at Petrolheadonism underground which meant we were really against the clock.

Since the show, we’ve made a few minor adjustments including all F8X upgrades from suspension secrets. This includes solid control arm bushes, adjustable drop links, camber arms, traction arms & toe arms. The guys at Suspension Secrets gave us the perfect track-spec suspension setup along with a much-needed alignment.

A lot has happened with our F80, looking back. We wanted to give you a full breakdown of the project since we get a lot of questions & enquiries about the mods we’re running. We have lots of customers asking us for the ‘Rhys-spec’ which always makes us smile.

Thanks for reading and feel free to comment on any experiences you have buying a high mileage BMW. Did you get burned like us?