Guide: The Suited GTS - a Historical & Technical Appraisal of the BMW E90 M3 CRT
BACKGROUND
In addition to ActiveHybrid drive system technology, a key aspect of BMW’s forthcoming electrified i3 and i8 range (anticipated for production during 2013) was the use of pioneering Carbon Fiber Reinforced Plastic passenger cells.
A part carbon, part plastic material subsequently injection moulded to form a cellular honeycomb, the production process of Carbon Fiber Reinforced Plastic (CFRP) enabled leftover cuttings to be reprocessed and then woven into mats of any size before being impregnated with synthetic resin and hardened.
During the i3 and i8 development stage, BMW decided to showcase its CFRP expertise by integrating the material to a limited run of M3s.
The resultant M3 CRT (for Carbon Racing Technology) was based on the four door E90 Sedan and, following the arrival of a concept during April 2011, was unveiled in production-ready trim at the BMW M night which took place at the Nurburgring 24 Hour race weekend the following June.
Unlike the plethora of M3 special editions that had begun to emerge since 2008, the CRT was no ordinary limited run sales booster. Instead, it combined the chassis and drivetrain enhancements of the super hardcore E92 M3 GTS Coupe launched back in late 2009 with a variety of lightweight components that were unique to the CRT.
Like the GTS, the CRT assembly process saw partially completed body-in-whites dispatched from the regular M3 production line in Regensburg to the BMW Motorsport facility some 120km south in Garching. From here, the batch of 67 CRT Sedans began to emerge during August 2011.
As per the GTS, the M3 CRT was not homologated for sale in North America on safety grounds.
BODYWORK
Externally, the CRT differed from a regular M3 Sedan on account of its CFRP hood and a custom CFRP aero kit unique to this lightweight special. Only one colour scheme was offered: Frozen Polar Silver Metallic with Melbourne Red Metallic highlights (the latter applied to the hood vents, side gills and the otherwise exposed CFRP spoilers). The front grilles were finished in matt black to match the wheels.
The CFRP as opposed to normally aluminium hood consisted of two carbonfibre sheets encased with an aramid composite honeycomb. It provided a weight saving of 50% over the key front axle zone.
The CFRP central front lip spoiler and curved rear trunk lid spoiler created specially for the CRT yielded some additional high speed stability.
Otherwise, the CRT was identical to any other E90 M3 Sedan which itself only shared the doors, trunk lid, windows and lights with regular 3-series variants. The aggressive nose assembly, vented hood with power bulge, flared fenders (vented at the front), exterior mirrors, side skirts and rear bumper were all M3-specific items. As usual, bright metal window trim was ditched in favour of dark Shadowline treatment.
Unless stated otherwise, body panels were fashioned from steel, the exception having been the bumpers, sills and mirror casings which were made from Olefin Thermoplastic.
INTERIOR
Perhaps the most visually striking aspect of the CRT was found in the cockpit where, instead of the usual power seats, BMW Motorsport added unique CFRP manual front buckets with exposed CFRP backs. Out back was pair of individual rear seats as opposed to the normal three-person bench.
Each car was trimmed in a combination of Black and Sakhir Orange extended Novillo leather with Sakhir Orange contrast stitching throughout. Also included was an alcantara-wrapped steering wheel, Sakhir Orange door sill plates, aluminum grain dashboard and door armrest trim, an individually numbered dashboard plaque and velour floor mats with Sakhir Orange edging.
The CRT’s sound-proofing was specially configured.
Included as standard was the normally optional automatic climate control, BMW Professional navigation system, high end BMW Individual audio system and Park Distance Control. Like the regular M3, electric windows, electric mirrors and Anthracite headliner were also fitted.
Inside, as per the regular M3, the CRT imported its basic architecture from the normal 3-series, but with a few special touches here and there.
Behind the three-spoke Motorsport-branded steering wheel was an instrument binnacle that featured thick aluminium bezels, red needles, a special 330kph / 200mph speedometer and a unique 9000rpm rev counter (inset with fuel and oil temperature read outs respectively).
Located in between the two main dials were an array of warning lights while additional information could be accessed via the iDrive screen located atop the centre of the dash.
Also unique to the M3 were additional buttons alongside the gear lever to adjust the Power (throttle response mode), Electronic Stability Control (ESC) and Dynamic Stability Control (DSC).
Other M3-specific equipment included an illuminated Motorsport-branded leather shift knob, an M Design driver's footrest and M3-branded door sill plates.
CHASSIS
Every M3 CRT started life as a standard E90 M3 Sedan pressed steel monocoque.
The M3’s custom front subframe and thrust plate were carried over along with the 63-litre fuel tank from the regular E90 which was mounted underneath the rear seat. As per the GTS, a smaller battery was added to save a little weight.
Suspension-wise, the GTS and CRT retained the MacPherson strut / multi-link arrangement of the normal M3 plus most of the usual goodies like reinforced front struts, stiffer bushings, forged alloy control arms, camber struts and wishbones and re-rated anti-roll bars.
Significantly though, the GTS and CRT came with two-way adjustable KW coil-over shocks and there was also a now rigidly bolted height-adjustable rear subframe. This enabled ride height to be reduced by up to 16mm at the front and 12mm at the rear while camber settings could similarly be tailored to the driver’s requirements.
Whereas the regular M3 came with cross-drilled and vented brake discs of 360mm diameter up front and 350mm at the rear, for the GTS and CRT these were switched to 378mm and 380mm items respectively. Also, the original single-piston calipers were exchanged for beefier six-piston front calipers and four-piston items at the rear.
Stainless steel Stahlflex brake lines were another GTS and CRT feature.
Standard issue wheels for the GTS and CRT were the normally optional 19-inch diameter Y-spoke Style 359M alloy wheels (9 and 10-inches wide front-to-rear). These were originally painted matt black and shod with Pirelli P Zero Corsa tyres (255/35 ZR19 and 285/30 ZR19 respectively).
Imported without further modification was the regular M3’s quicker-than-normal variable assistance Servotronic steering.
ENGINE / TRANSMISSION
Aside from a Silver instead of Fire Orange cam cover, the CRT engine was identical to the enlarged version of the S65 B40 engine found in the GTS.
For this enhanced GTS / CRT application, the size of the cylinder bores was kept at 92mm, but stroke was lengthened from 75.2mm to 82mm (a gain of 6.8mm). As a consequence, overall displacement went from 3999cc to 4361cc which represented an increase of 362cc.
In addition, the GTS / CRT motor was given a lightweight free-flow exhaust with titanium silencers and trick catalytic converters.
As a result, peak output went from 414bhp to 444bhp at an unchanged 8300rpm and from 295lb-ft at 3900rpm to 325lb-ft at 3750rpm.
Aside from these upgrades, the rest of the regular S65 B40’s characteristics were carried over; these were essentially eight cylinder versions of the F1-inspired normally aspirated V10 motors used by the contemporary M5 and M6.
They featured an all-alloy construction, 90° vee angle, dual overhead camshafts per bank and four valves per cylinder. A split two-piece crankcase was also used along with a forged five-bearing crankshaft, cast aluminium crankshaft and pistons, a semi-dry-sump lubrication system, high-pressure double VANOS variable valve timing plus lightweight valves and hollow camshafts.
To maximise the engine’s responsiveness, simultaneously actuated and electronically-controlled individual throttle assemblies were installed for each cylinder.
Compression was 12.0:1 and engine management was via an MSS60 system powered by a trio of 32-bit microprocessors.
Whereas the regular M3 could be configured with a ZF six-speed manual gearbox, the CRT (like the GTS) was offered exclusively with BMW’s M Double Clutch Transmission (M-DCT) produced in collaboration with Getrag. In manual mode, gear shifts were carried out via F1-style shift paddles located behind the steering wheel. Shift speed could be adjusted via a button on the transmission tunnel.
Uniquely, the M-DCT set-up for the GTS and CRT was modified with increased oil capacity and specific software calibration.
Also present was BMW’s Variable M Differential Lock - effectively a more advanced version of a traditional limited-slip differential. It activated when a difference in rotational speed between the rear wheels pressurised a viscous silicon fluid which in turn operated a multi-disc clutch that directed extra power to the wheel with the greatest traction.
For the GTS / CRT, the M3’s Dynamic Stability Control system (DSC) was specially adapted to make allowances for the extreme high performance nature of these uprated variants.
DSC (which could be disabled if desired) was able to reduce engine power and in addition (or independently) apply brake force to any single wheel. DSC also incorporated a Brake Standby facility that anticipated hard braking by pressuring the brake pad up against the disc when the driver abruptly reduced throttle. Other features included Brake Drying (which pressured the pad up against the disc when the rain sensor detected moisture) and Start-Off Assistant (which kept the brakes applied for one second after the driver's foot was removed from the brake pedal in uphill conditions).
WEIGHT / PERFORMANCE
At 1580kg, the CRT tipped the scales 45kg lighter than a standard post-March 2010 E90 M3 Sedan, but the actual weight saving once the normally optional equipment included as standard was taken into account represented a 70kg reduction.
The 0-62mph time dropped from 4.9 seconds to just 4.4 (identical to an M3 GTS) while top speed was electronically limited to 180mph.
END OF PRODUCTION
Following completion of the left-hand drive ‘00’ numbered prototype, BMW Motorsport built 67 identical examples of the M3 CRT between August and October of 2011.
Of these 67 production cars, 62 were left-hand drive and five were right-hand drive.
Text copyright: Supercar Nostalgia
Photo copyright: BMW - https://www.bmw.com
