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See the September edition of SPEED & SOUND for the Supercharged E92 M3 article: ”Holy Smoke” Download the full article here...
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“THIS TRULY IS A FOUR-SEATER V8 SUPERCAR OF INTERNATIONAL STANDARD”
First impressions are lasting impressions, a truism that applies to interpersonal relationships as well as the way people relate to motorcars. In developing the supercharged installation for the V8-engined BMW M3, the team at RGMotorsport knew that the final product had to convey an immediate sense of sophistication at least on a par with the standards set by BMW in Munich. “From the moment a driver slides behind the wheel, pushes the start button on the dash and hears the engine start up for the first time, our product had to sound and feel right,” says Rob Green, founding partner of RGMotorsport. “This meant that while the exhaust note and induction sound had to be just that little bit special, the under-bonnet mechanical noise intrusion had to be minimal. And of course, nine times out of 10 a typical customer would want to take a look under the bonnet, so, aesthetically too, this installation had to convey both a sense of excitement as well as top-level craftsmanship.” Rob Green admits that he became almost obsessed with the E92 supercharged installation devoting nearly six months full-time to the project, even though he can draw on 15 years of experience in supercharging. In addition, RGMotorsport’s chief designer Donovan Penaluna worked hand-in-hand with Rob Green every step of the way, translating countless hours of discussions into workable designs that then had to be fabricated, and then refined in the trial fitment stages.
At the heart of the installation, of course, is the supercharger unit itself. With a relationship with the internationally acclaimed Vortech company going back more than a decade, RGMotorsport were able to specify the exact model to suit the engine’s 3 999 cc capacity, as well as accommodate the unit within the confines of the already rather component-packed engine bay. The conversion also had to follow RGMotorsport’s strict policy of making each and every supercharging conversion reversible – in other words, the car needs to have the possibility of being returned to stock production specification in the event of the owner deciding to sell the car and retain the supercharger kit. This of course means no cutting of bodywork to accommodate all the components of the kit. There was another aspect to the “no cut” policy that figures strongly in RGMotorsport’s plans: this kit is scheduled to be marketed in kit form in international markets through approved dealers, and for this reason its completely “bolt-on” configuration is doubly important. “The big difference in developing this kit, as far as design was concerned, is that aesthetics, the overall under-bonnet appearance, was more import than in any previous project we’ve tackled,” says Donovan Penaluna.
“In addition, we worked harder than ever before to achieve optimum airflow characteristics, in terms of both air volume, and perhaps most important, charge cool temperatures – the temperature of the air after it has passed through the supercharger and the charge-cooler and enters the engine.” In this regard, Rob Green waxes lyrical about the characteristics of the RGMotorsport E92 supercharged kit. “We measure air temperatures at every critical point along the induction path. With this installation, at an ambient (outside air) temperature of 25 degrees C, after the air has been compressed by the supercharger, the charge temperatures rise to 110 degrees C. The air is then channelled through our liquid charge cooler system, and at the point where it enters the engines intake port system the temperature has dropped down to 46 degrees C. That’s a massive drop in temperature and it was key to offering our kit as a complete bolt-on installation, with no necessity to modify any engine internals! Even with the E92 V8’s high compression ratio of 12,0:1, we are looking at a completely detonation-free scenario, thanks to the ultra low temperatures of the air charge at its final destination.”
The challenge facing Donovan Penaluna was not just to keep temperatures down, but also to ensure that the volume of air was of a very high magnitude. Rob Green was adamant from the start that the system had to flow 1 650 CFM (cubic feet per minute), an American rule of thumb that translates to a theoretical 1 000 horsepower (750 kW) capability. “We know our customers well, and even with the awesome 504 kW capability of the standard kit, there will be those fanatics who are complete horsepower junkies and will want more power. To take the engine up to 750 kiloWatts obviously the internals will have to be re-worked – custom conrods, pistons, crank and the like – and we wanted to have that flow capability built into the original kit design for those who want it,” says Green.
Rob Green says that the induction layout was helped by the original design of the production M3, which uses three intake points for incoming air to the car’s under bonnet. “There is a duct on the bonnet, the big one under the bumper line and an intake in the kidney grilles. This is the first time on a BMW supercharged conversion that we’ve been able to use the kidney grilles as a source of intake air.” Donovan Penaluna points out that this entire RGMotorsport induction system is a cold-air system, unlike some competing conversions that merely install a cone air filter in the under-bonnet space, thus increasing charge air temperatures to a critical level.
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DESIGNING THE SYSTEM
“The starting point for our conversions is obviously the supercharger unit itself” says Donovan. “In view of our criteria, which include the options to go for a high-boost, high power installation at a later stage, we chose the Vortech V2 T-Trim centrifugal unit, which is able to supply the required volume of air,” says Donovan. This is mounted on an ultra stiff, laser and water jet cut bracket assembly to the right side of the engine, and driven by a ten-rib serpentine belt, and an RGMotorsport crankshaft pulley. This pulley, machined from billet aluminium, has three belt drive channels, to accept the two standard belts used by BMW for its ancillaries such as the water pump, alternator and air-conditioner, and the third channel driving the Vortech V2.
Using carbon fibre, an elegant and ultra-efficient ducting system was designed to channel the air into the supercharger compressor. The compressed air is then fed via equally-showroom finished aluminium ducting into the water-cooled charge cooler, which has a 1 650 CFM flow capability. This charge cooler is basically a liquid cooled intercooler mounted horizontally on the top of the engine, nestling between the two cylinder banks of the V8. To provide cool fluid for this charge cooler of 16 litre coolant capacity, which is independent of the stock BMW engine coolant system, dual heat exchangers are mounted in the nose with a direct cool air-stream path, and plumbed into the charger cooler reservoir. The coolant is then circulated using dual high volume electric water pumps.
An important point to note is that the charge cooler is contained within an integral plenum housing crafted of aluminium, enabling the cooled air to be fed up through the core to the plenum chamber at the top of the integral unit, which houses the eight machined billet aluminium ram tubes. The cooled, dense high-volume of air is forced into the engine, and to accommodate the much greater volume of introduced air, significantly larger fuel injector units are employed to provide the correct air-fuel ratios. The standard injector units, with a capacity of 280 cc per injector, are replaced by eight injectors with a 430 cc capability.
“The prime objective, as already mentioned, was no structural cutting,” says Donovan. “Modern engine compartments are notorious for being crammed full of equipment and our challenge from a pure practical point of view was to get everything to fit. We made up jigs to measure under-bonnet space as a starting point, and then I designed the components on CAD around the data that we captured,” says Donovan. “ The clearances we needed also allowed for a degree of engine movement, or what Rob Green calls ‘engine climb’. To maximise reliability, the installation was also designed to be integral with the engine, so that it would move with the engine, rather than having components that are mounted on the bodywork, and then put under tension when the engine rocks, or climbs under torque.”
In addition to the supercharging hardware, the RGMotorsport kit will include a special high-performance stainless steel exhaust system, which adds a delightful crackle to the rather subdued exhaust note of the standard V8-engined M3.
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PERFORMANCE
“One of the aspects of the conversion I am ecstatic about is the management of air temperatures”, says Rob Green. “ We had a target of 0,65 Bar of boost at sea level and 0,5 Bar of boost at altitude – most people assume that a supercharger is unaffected by the lower air pressure at high altitude where our RGMotorsport headquarters is based, but this is not the case. The amount of air a supercharger compresses is directly related to ambient air pressure.
“To produce those levels of boost, the Vortech V2 centrifugal supercharger is usually spun close to its designed maximum of 55 000 rpm. With such good charge air characteristics, we were able to reduce the peak rpm of the supercharger unit to 46 500 rpm and still register the required boost levels. Obviously this has a significant reliability effect on the longevity of the belt drive system and on the supercharger itself. And a spin-off, to coin a phrase, is that the under-bonnet noise levels, already exemplary, I might add, are further reduced.
RGMotorsport’s Eletronics Division, under the direction of Steve Green, was employed to re-map engine, using the Dastek-produced Unichip Q system, which enables the standard BMW ECU to be left undisturbed – again, reversibility of the conversion, returning the car back to standard if necessary, remained a prime consideration throughout the RGMotorsport facility.
The re-mapping included altering the timing on the inlet camshaft operation, as well as the obvious fuelling and ignition spark programming. And in addition, RGMotorsport employs dual boost dump/recirculation valves to make the transition between throttle-on and throttle-off applications smoother. Intensive work by Steve Green on the RGMotorsport dynamometer resulted in power figures that even exceeded the company’s expectations. When the car was released for initial shakedown runs on the road in July, it had returned dyno-measured figures of 504 kW at 7 600 rpm and 634 Nm of torque at 6000 rpm .
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STILL OPERATES LIKE A STOCK M3 – UNTIL YOU FLOOR IT!
Initial shake-down tests on the prototype included a trip down to Mpumalanga from Johannesburg. In attendance in the RGMotorsport convoy were Reghardt Roets, South African production Car Champion, and veteran motoring journalist Stuart Johnston.
Johnston was able to try the car in the Lowveld on empty roads and says his hair still raises up on the back of his neck when he recalls the first time he really wrung the Supercharged M3 out. “I expected something a bit wild and woolly, but it was totally mild-mannered, at first, low-speed sampling. It pulled away like a normal M3, but with one big difference:. the slightest depression of the throttle pedal brought a much bigger response.“On the other hand, the car was totally controllable on the throttle, with no lag followed by a huge bulge in the power-band. Everything was totally linear. After gradually building speed, Reghardt Roets, who was in the passenger seat, was getting a bit tired of this pussy-footing approach and told me to boot it. “I did so, gradually wound it up to peak revs- somewhere over 8 000 rpm, in third, which means you are already doing over 200 km/h. “I hooked fourth and fed in the power and at that point we were cresting a slight rise, and the road curved slightly to the left. Incredibly, the rear wheels started to break traction, ever so slightly, in fourth gear! It wasn’t scary or anything, because the power is so linear. Just mightily impressive!” In a subsequent article on the shake down run for the mass-circulation Star Motoring, Johnston said driving the M3 was the nearest four-wheeled experience to that of a 1 000 cc Superbike. “You decide how far up the horizon you want to be and just crack open the throttle, and you are THERE!”
THE REST OF THE CAR IS STOCK
Rob Green has taken the decision to supply the kit as a complete bolt-on unit. This means that the rest of the car is left stock, including the clutch, drive-train, and brakes. Obviously owners can fit an expensive competition clutch if they like to indulge in constant racing starts, but Rob points out that he would rather have the clutch as a so-called “safety valve” in the system than the drive-train, such as the diff and the axles.
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Performance tests conducted on the RGM Supercharged BMW E92 M3 utilizing the Racelogic V BOX
Performance testing was conducted at the Tarlton International Raceway on the 1st September 2009. This is the beginning of our summer and the ambient temperatures were around 24 degrees Celcius at the time that the tests were conducted. Totally street legal tyres were utilized and no intermediates ( semi slicks ) were used at any time. Besides the tests conducted at Tarlton Raceway we conducted various test on National Roads and once again only street legal tyres were utilized. Comparison tests were conducted under the same conditions regarding the Venue, temperatures and tyres.
* PLEASE NOTE THAT ALL TESTS WERE CONDUCTED @ 5500 FEET ABOVE SEA LEVEL*
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0-100 km/h
1/4 mile time
1/4 mile speed
800 metre time
800 metre speed
1000 metre speed
Top Speed
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BMW E92 M3 STANDARD
5.8 seconds
13.83 seconds
166.9 km/h
22.2 seconds
201 km/h
217.5 km/h
260 km/h
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BMW E92 M3 RGM SUPERCHARGED
4.28 seconds
12.4 seconds
193.8 km/h
19.4 seconds
240 km/h
258 km/h
320 km/h (governor removed) redline in top gear
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RGMotorsport’s Supercharged BMW e92 M3 sets a BMW club record at Kyalami
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Video clips of the Supercharged E92 M3 speed runs and on the Dyno here
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See Development pics of the Supercharged E92 M3 here
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