3-Generations of M5 Tuning from Dinan, AC Schnitzer and Hamman

Rules are made to be broken--at least that's what I used to tell myself those many times I awaited my fate sitting outside the principal's office. Unfortunately, the principal failed to agree with me on this point.

Fortunately, there are others who feel as I do--and more fortunate is that some of these enemies of convention work for car companies. They're the ones who reject tradition, who strike out in new directions. They're the ones who asked why a passenger sedan, with its requisite four doors and room for five, also had to have stodgy handling, lackluster styling and milquetoast performance. They're the ones who, for better part of three decades at BMW, have shrugged off the limitations of the basic sedan and replaced them with the skills of the sports car. Wrought from this philosophy is the modern performance sedan.

In Europe, tuners such as Alpina and Schnitzer have traditionally picked where BMW left off, building unique limited editions. Not wanting the tail to wag the dog, BMW responded by dipping into its motorsports think tank to create the M Series. The first practical M Series car was the European M535i built on the E12 first-generation chassis. The most noticeable aspect of an M535i is the deep front spoiler and lowered stance. Under the hood lurked a 218-hp. single overhead cam engine. Many would consider the M535i more a styling and handling exercise than an outright motorsport pedigree car. Even so, crash and emissions legislation would keep the M535i on the other side of the Atlantic. Here in the U.S., we would have to wait until 1988 and the second 5 Series E28 iteration to get a true M535i; this time it was called an M5. It was also the year when two other M cars--the M3 and M6--made it to American shores.

The M5 began with a standard 535, which then was given a healthy dose of BMW Motorsport magic. At the heart of the matter was a 3453cc engine (type M88/3) with two cams and 24 valves. The basic design was borrowed from the back of BMW's M1 supercar and shared the same 93.4mm bore and 84mm stroke, but differed with a 10.5:1 compression ratio and a Bosch engine management system instead of Kugelfisher mechanical injection. By virtue of modern engine management systems and a higher compression ratio, in Euro trim the M5 engine put out 9 more hp than the 277-hp type M88 M1 engine. Strangled by emissions equipment and a lower compression ratio, the U.S. M5 engine put out "only" 256 hp at 6500 rpm, providing an electronically governed top speed of 150 mph. And 0 to 60 mph came up in a scant 6.7 sec (the European model shaved 0.7 sec from that time), making it one of the fastest sedans of the period.

Despite a lofty price tag of over 50k out the door, buyers lined up and purchased 1,235 first-generation M5 models, although only 500 had been planned for U.S. allocation (the number of M5 cars sold here differs greatly depending on the source). The M5 proved particularly popular with diehard BMW fans and, with its capable package, not surprising soon found its way to driver schools and BMW club track events. BMW's twin-cam M5 and M6 engines also proved a favorite with the tuners specializing in extreme renditions. Steve White's modified 1988 M5 is one such car.

Dinan Motorsports M5
The car was purchased from a BMW club member who spent his BMW M5 rebate check on performance modifications from Dinan Engineering and Frank Fahey Motorsports. The most dramatic modification was the installation of a Dinan Stage II 3.9-liter stroker engine. Larger displacement M engines aren't entirely new as BMW sold a 3.5-liter M5 from 1991 to 1993. In Europe, later M5s could be had with 3.8-liter displacement engines, giving 340 hp and sub-6.0-sec 0 to 60 mph times.

Dinan's 3.9-liter engine followed this concept with a 94.6mm bore and 92mm stroke. The increased bore is accomplished by means of custom forged pistons with a 10.2:1 compression ratio and a custom billet crankshaft with 92mm stroke. Combined with Dinan's performance camshafts, cam gear and engine management software, the engine is said to produce 365 hp at 6500 rpm and 366 ft-lb of torque at 4500 rpm. A Sachs sport clutch transmits the power to the stock M5 gearbox. Gear selection is through a short shift kit.

A European M5 header with Jet-Hot coating and custom 3.0-in. diameter exhaust system delivers the necessary exhalation. The European header is a beautifully crafted piece and contributes to the European M535i's 30 additional horsepower. A trick device on this car is the quick release catalytic converter with track pipe. The previous owner regularly took this car on the track, and made removing the catalytic converter a simple job involving quick releases. For obvious reasons, the catalytic converter is always used on the street and, because the car is currently fitted with a high-performance catalytic converter, Steve now also uses the cat on the track.

Track duties dictated compromising somewhat the car's street driveability with modifications to the suspension and braking systems. Suspension Techniques provided the custom-wound springs, thicker anti-roll bars and custom-valved Bilstein struts and shocks. Other enhancements include a Racing Dynamics front strut brace and urethane suspension bushings. Up front the brakes are the stock 11.8-in. vented rotors. The rear brake components were removed and replaced with 0.6-in.-larger 11.8-in. rotors and calipers from a 1993 M5. A set of de riguer stainless steel brake lines is used all around. Front brake cooling is provided via two air ducts and tubes in the front spoiler. Mounting the ducts required removing the spoiler-mounted fog lights.

For running gear, Steve ordered a set of custom-built HRE wheels, which measure an inch wider up front (8.5 x 16), and the rear wheels are two inches wider than stock (9.5 x 16). Dunlop D40 M2 high-performance radials, size 245/45-16 are Steve's tire of choice.

In the year that he has owned this particular M5, Steve has come to appreciate the motorsport heritage and the practical nature of this four-door supercar. It has become his daily driver, and to date it has over 100,000 miles on the odometer, not at all uncommon for M5s. Even as a daily driver, Steve occasionally straps in with the five-point harnesses and drives his car as the gods and BMW Motorsport intended. When he fancies a bit of tuning from the fatherland, he climbs into his Schnitzer S5 Silhouette.

AC Schnitzer S5 Silhouette
Longtime readers of ec are likely to remember AC Schnitzer's Silhouette. We reported on this particular car in our April 1992 issue as one of the first complete E34 tuning programs. At the time the car was under the care of Claus Ettensburger from CEC. As the sole U.S. distributor for AC Schnitzer products, Claus wanted to have a showcase for the complete line of AC Schnitzer E34 products. So he sent his personal car to Germany for the Full Monty.

Most noticeable is the Schnitzer Silhouette wide-body kit, consisting of a front spoiler, rear apron, side skirts, rear wing and four fender arches. Schnitzer's Silhouette was styled as an exercise in race-like styling without adversely altering the silhouette of the vehicle. Whereas most Schnitzer body kits are made from PUR Rim, the Silhouette kit is constructed from lightweight fiberglass with Kevlar reinforcement in the rear wing.

The large fender flares enable some serious rubber to be stuffed underneath. Initially the Silhouette was fitted with 3-piece 9 x17s in front and massive 11 x 17s in the rear, but Steve replaced stockers with Schnitzer one-piece forged units. For tiresSteve uses Dunlop SP 8000s (255/40-18 in front and 285/35-18 in the rear). Other items in the package include blackout headlights, mono-windshield wiper conversion, badges and floor mats.

An aggressive stance is provided by Schnitzer's sport suspension, designed to lower the car by about 35mm yet still retain a reasonable comfort level. As there are so many E34 varieties in Europe, Schnitzer offers a kit for every version, including those with self-leveling suspensions. This car has Schnitzer/Bilstein struts and shocks, Schnitzer springs and adjustable anti-roll bars (26mm in front and 19mm in the rear). Since our first road test, the Silhouette's suspension has been unchanged save for the addition of a Racing Dynamics stress bar. Our driver who tested the car at the time remarked, "The large contact surface on the ground, coupled with the massive tires and wheels, provided the kind of performance that I've come to expect from the best two-door sport coupes."

Upon opening the hood, it's hard not to notice the valve cover bearing the AC Schnitzer name or the red 3.7 numbers on the matching airflow sensor cover. This engine is only one of the E34 chassis engines available from Schnitzer at the time. Six-cylinder engines are available with displacements ranging from 2.7L up to 3.7L. It's been said the engine in this particular car measures in even larger at 3.8L, but that was not able to be confirmed at the time of writing. The largest 6-cylinder engine advertised is Schnitzer's S5 3.7L, measuring 3627cc with a 92.5mm bore and 90mm stroke compared to 92mm and 82mm for a standard 535i.

Accomplishing such gains requires replacing many engine components. In this case, Schnitzer replaces the pistons, crankshaft and connecting rods. Modifications are done to the cylinder head, manifolds, block and engine management system. The exhaust tract is freed up with a complete exhaust system, including a header, catalytic converter and mufflers.

Since we last saw Schnitzer's S5 Silhouette, the only detail changes are the addition of window tinting and a Clarion 6-gazillion-watt stereo system. For now, the Silhouette is driven only occasionally as it is once again at CEC awaiting a new home. Steve isn't too keen on selling it, but how many wild 5 Series cars does one need? Particularly since there is an all-new M5 coming around the corner.

With the passing of the E34 chassis, the M5 also passed. Having installed a large V8 engine into the new E39 5 Series chassis, BMW felt there was no need for an M5 model and left it up to the tuning industry to provide the go-fast bits. Currently, the top-of-the-line 5 Series is BMW's 540i. With a manual transmission, the 540i beats the E34 M5 with a 0-to-60-mph time of 5.8 sec..

Hamann 540i
Richard Hamann is not one of the best known European BMW tuners, yet he's managed to build some of the wildest yet tasteful BMW cars. Hamann draws from over 20 years of when putting together his projects. His racing resume includes three German Special Touring Car Trophies behind the wheel of an M1, seat time in Group C, DTM and Formula 3. In 1986 Hamann began to concentrate on building high-performance street cars instead of race driving. One of the first projects was an E30 with a turbocharger, producing 348 hp. From there, Hamann began to experiment with different technologies, even putting a 5.7L V12 engine in an E36 3-Series. The last Hamann cars to grace the pages of ec were two Hamann STW M3s assembled here in the US by Hamann's two distributors (ec 4/98 ec 5/98). Hamann's STW is basically a race car for the street with a body kit, lowered suspension, and ultra-wide wheels.

A bit more subdued than the STW is Hamann's 5 Series program. This particular 5er-based Hamann car was built by Chris Contreras from D2 Motorsport. Like so many race-bred tuner cars, this one is slammed to the ground with a set of sport springs and shocks from Hamann. The kit is said to lower the car by 40mm in front and 20mm in the rear. But, with a deep front spoiler, the effect is much more pronounced. Adding to this effect is a set of Hamann side skirts, rear valance and sport mirrors. The owner of this car elected to forego the Hamann trunk-mounted rear wing and roof spoiler.

On the performance side of the equation, this car has been fitted with a Hamann Motorsport dual exhaust system with twin oval stainless steel tips protruding from the rear valance. In Europe, Hamann offers a few different engine packages that aren't available here. Also available is Hamann's own traction control and top speed de-limiter.

D2's Contreras also elected to fit a set of 8.5 x 19-in. Hamann wheels. Hamann has several different wheel sizes and designs available for the E34, from 8.5 x 17 up to 9 x 19. Wrapped around these wheels is a set of German-made Continental Sport Contact tires, size 245/35 ZR-19. These were the tires developed by Continental for Porsche's then new 993 chassis cars. They may be a bit dated in technology, but they're still a great performance tire. D2 sent the 540i down to Cool Tech for a Brembo brake upgrade. Brembo brakes are a true lightweight racing caliper. A set of 14-in. vented rotors replace the stock 12.8mm rotors in front and the 11.8mm rotors in the rear.

Inside the passenger compartment, D2 installed a set of Hamann pedal covers and a brushed aluminum interior trim kit. Although the steering wheel appears different, it's really a stock wheel with a Hamann center logo.

BMW Continues to rewrite the rules of sedans. While other manufacturers have followed BMW's lead, not all have been successful in recreating the sport sedan recipe. Until a new M5 is offered for sale, those who want to have a bit of motorsport heritage can buy used or build something of their own.