BMW M3 E92: chassis tuning, servicing and E85 remapping at Shiftech Nantes

Mathis, aged 25, is an automotive content creator based in Rennes. Active on Instagram (@matrpm) and TikTok (@matcvn), he has been documenting the step-by-step build of his cars for several years, unfiltered and without worrying about the polarised opinions it generates on social media.

Before the M3, he drove a BMW M240i, a car to which he had already made numerous aesthetic and mechanical modifications. The switch to the naturally aspirated V8 of the E92 M3 marks a change of direction: here, every part is chosen to last, and the approach is clearly performance-oriented.

His philosophy is simple: test everything, document the results, and keep only what works. If a part doesn’t measure up, it’s removed. The car must remain 100 per cent reversible for as long as possible, which also explains his hesitation over welding on a half-roll bar.

The starting point

Mathis’s E92 M3 was purchased with around 100,000 km on the clock and in sound mechanical condition. By the time it arrived at Shiftech Nantes, the car already featured several modifications:

Engine and exhaust system: Macht Schnell intake system with carbon fibre plenum and Macht Schnell pulley, Burger Motorsport filters on the intake ducts. Exhaust system: Akrapovic slip-on rear silencer with carbon tailpipes, X-pipe, and catalytic converters replaced by titanium intermediate converters. Mathis chose not to fit the full Akrapovic system (with the original catalytic converters), as he found it sounded too muffled in this configuration.

Chassis and brakes: KW height-adjustable short springs, compatible with the original EDC electronic suspension. Megane RS four-piston brakes at the front, original callipers at the rear.

Exterior: 18-inch OZ Racing Division Pista wheels, fitted with 275 tyres on all four corners. Front splitter, LCI-style front and rear lights in black.

Interior: original configuration at the time of the modification.

Tested on the dynamometer prior to remapping, the M3 produced 395 ch on 98-octane unleaded petrol, a figure consistent for an E92 with an open intake and exhaust system. For reference, standard E92 M3s with high mileage often measure around 365 ch on the dynamometer, well below the 420 ch claimed by the manufacturer.

Before carrying out any work on the engine mapping or the chassis, the first task of the day was a full engine service. With a high-revving naturally aspirated V8 like the S65 in the E92 M3, maintenance is no minor matter: it’s essential for the engine to continue delivering its power and withstanding the stresses placed on it, especially when you start driving on the track.

Motul 300V engine oil change

The S65 requires 9.2 litres of oil including the filter, making it a particularly oil-hungry engine. A distinctive feature of this engine block is that it has two drain plugs, and both seals must be replaced at every oil change. We’re using Motul 300V 10W60 here, a competition oil designed for very high-revving engines. As the S65 can rev up to 8,400 rpm, the choice of lubricant is crucial: you need an oil capable of maintaining its protective film at revs and temperatures that most production engines never reach.

Spark plugs, filter and brake fluid

The spark plugs have been replaced (the ignition coils, meanwhile, were still in good condition, but remain an area to monitor on this engine, with a replacement cost of around 1,300 euros for genuine parts). The filter has been changed, and the brake fluid has been bled and replaced with RBF 660, a high-boiling-point fluid that is essential whenever the brakes are subjected to intensive use on the track. Conventional brake fluid loses effectiveness as the temperature rises in the calipers: RBF 660 significantly pushes back this limit.

The second project – and probably the one requiring the most labour – involved the complete replacement of the suspension. Until now, Mathis had been driving with a KW kit comprising height-adjustable short springs, fitted to the original electronically controlled (EDC) shock absorbers. This is a common and effective solution on E92 M3s fitted with EDC: it allows the body to be lowered at a lower cost (around 700 to 800 euros) whilst retaining the electronically controlled dampers. However, for regular track use, the limitations become apparent: the damping remains as per the original set-up, with no possibility of adjusting either compression or rebound.

KW V3 coilover kits

The KW V3 coilover kits replace the shock absorber and spring assembly with a complete kit, offering independent compression and rebound adjustment. It’s a more substantial investment (between 3,000 and 4,000 euros for this application, including EDC), but the level of control over the chassis’s behaviour is unrivalled.

Removing the original suspension revealed a running gear in very good condition: no leaks from the shock absorbers, no play; everything was clean for a car with 100,000 km on the clock. The controlled suspension system was disconnected, the shock absorbers removed from the front and rear wheel hubs, and the KW V3 shock-absorber units fitted in their place.

Important point: the ride height was not lowered. Mathis already drives with a significant drop (around 90 mm compared to the original height) and consistently scrapes over speed bumps. Lowering it any further would render the car unusable for everyday driving. The aim here was not aesthetic but functional: to stiffen the chassis and improve dynamic handling, whilst maintaining the same ground clearance.

Reinforced anti-roll bars

In addition to the coil-over kits, reinforced anti-roll bars have been fitted: 22 mm at the front and 27 mm at the rear, with adjustable links. Anti-roll bars control body roll when cornering and directly influence the vehicle’s understeer/oversteer balance. The adjustable links allow the bar’s preload to be adjusted according to the desired handling characteristics: when shorter, they stiffen the anti-roll effect; when longer, they soften it.

Wheel alignment check

After reassembly, the car was taken for a full wheel alignment check. On the E92 M3, replacing the threaded strut assemblies without altering the strut tower or the rear hub eccentric should, in theory, not affect the toe-in, but a check is still essential to ensure safe driving and to get the most out of the new suspension.

The final mechanical modification before the dynamometer test: replacing the original driver’s seat with a Recaro Sportster CS. This is a semi-bucket seat, designed for both road and track use, offering significantly better lateral support than the original seat whilst remaining comfortable for everyday use.

The Recaro Sportster CS is mounted on slim mounting plates, which lowers the driving position slightly without requiring any additional shims. The trade-off: the loss of electric adjustments (recline, motorised height) and the heated seat. For Mathis, this compromise is acceptable, especially as the backrest can still be reclined manually.

The passenger seat has remained as standard for the time being, with the idea of fitting a second one at a later date. The visual impact is immediate: the Recaro transforms the atmosphere of the cabin and gives the M3 a much more dynamic character.

Next steps planned for the cabin: racing harnesses and a half-roll cage (bolted or welded – still under consideration).

ECU readout

A distinctive feature of the E92 M3’s ECUs is that a full readout of the original file takes approximately 1 hour and 30 minutes. This is significantly longer than for most vehicles processed in-house, but it is an essential step to ensure a complete backup of the original ECU is available should the need arise. Writing the new map is quicker: between 20 and 30 minutes. The read-out tool used is Autotuner, Shiftech’s technical partner for ECU access.

Test conditions

The dynamometer test was carried out in high-temperature conditions: 32°C at the start of the session, 42°C at the end. The S65 V8 heats up the dynamometer environment considerably, which affects the measurements. By way of comparison, the previous dynamometer test on this same car (in January) was carried out at 14°C, yielding a result of 395 ch. The conditions on the day were therefore less favourable in terms of air density.

Result

Following Stage 2 remapping for E85, Mathis’s E92 M3 produced 434.5 ch and 425.5 Nm on the dynamometer. The power curve is clean, with the engine revving up to 8,300 rpm (the rev limiter retained at its original setting to ensure reliability). The increase compared with the previous measurement (395 ch on SP98, without decat) stems from two combined factors: the removal of the catalytic converters (carried out between the two tests) and the optimised E85 mapping.

The switch to ethanol also brings an economic benefit in everyday use: at 0.70 to 0.75 euros per litre, the cost per kilometre falls significantly compared with SP98, even taking into account the higher fuel consumption inherent in E85.

The work carried out on Mathis’s M3 E92 at Shiftech Nantes illustrates an approach that is becoming increasingly common in projects at the centre: combining servicing, chassis work and remapping in a single session, whilst maintaining overall technical consistency.

Fitting a Stage 2 map to an engine with worn-out oil or spark plugs that are at the end of their life means compromising on reliability and performance. Similarly, investing in high-end threaded map chips for a vehicle whose running gear has never been checked is like building on an unstable foundation. The advantage of having everything done at a single centre is that each service is designed to complement the others, and the whole system is validated before the car leaves.

On the E92 M3 in particular, the Nantes centre has developed specialist expertise in the S65 V8: ECU diagnostics, E85 mapping, and engine and chassis maintenance. It’s a model that Julien and his team know inside out, from oil changes to threaded manifolds and dynamometer testing.

• Shiftech Centre, Nantes: opening hours, how to get there, contact details

• BMW M3 E92 engine remapping: Stage 1 and Stage 2 performance gains

• BMW engine remapping: all available BMW models

• E85 conversion in Nantes: FlexFuel and Flex+

Shiftech Nantes

6 Rue du Carré Norgands

44880 Sautron

Tel.: 02 55 99 78 78

Open Monday to Friday from 9.00 am to 12.30 pm and from 2.00 pm to 6.00 pm.

Open on Saturdays from 9.00 am to 12.30 pm and from 2.00 pm to 6.00 pm.

Closed on Sundays.

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