In Depth: 2007 BMW E92 M3 Awesome 420bhp at 8400rpm
BMW’s ‘Efficient Dynamics’ philosophy goes into the new M3 Engine
The very name M3 symbolises performance and accentuates superior power. The secret of the M3’s success is its unique blend of racetrack and daily driving abilities. During the 77th Geneva Motor Show from the 8th to the 18th of March, the M3 Concept was finally unveiled, in a ‘chrome shadow’ paint finish. The first thing that catches the eye is the CFRP (Carbon Fibre Reinforced Plastic) roof panel, as previously introduced on the limited-edition E46 M3 CSL Coupe and on the current M6 Coupe. This dominating feature of Formula 1-class material is left visible and clear coated to exhibit technology and remain as lightweight as possible. It also makes the vehicle’s height appear lower than one would perceive, increasing the affect of its wide stance and low centre of gravity.
The lightweight aluminium engine compartment lid shapes a wide and robust bulging curvature known as the ‘Powerdome’, complete with heat escape vents. Sharply defined wheel arches and 20mm wider front fenders house the full-aluminium suspension assembly and huge 19” Y-spoke rims which weigh a mere 8 kg each. Symbolising the car’s motoring spirit are the 3 large cool air intakes at the front with fog lamps missing altogether. Another cooling feature is the trademark M-style side vents with integrated three dimensional indicating lights.
The M3’s sidewalls are made from an advanced synthetic material. M-style aerodynamic side mirrors have also been specially designed to reduce drag. A discreet bootlid spoiler (also known as the Gurney Flap), sports side skirts and rear diffuser guarantee the required downforce to keep this monster firmly planted. The look of the rear diffuser is enhanced by the subdividing modelled struts above the quad tailpipes, creating a somewhat similar look as the front intakes.
Right, that’s enough about the exterior, now lets get down to the engine. The biggest change in the new M3 is probably its transformation from the previous 3.2 litre in-line 6 powerplant on the E46 to the new 4.0 litre V-8 (banked at 90 degrees) on this new BMW E92 M3. The reason for moving away from the iron-block 3.2 litre straight-6 to a V-8 is not because Formula One went from V-10s to V-8s in the 2006 season as speculated. Helmut Himmel, head of M engine project said that the actual reasons are due to concerns over Euro5 and CARB emissions regulations and also the fact that the space between cylinders sat at just 4mm apart, which is right at the limit before head gasket troubles creep in.
Himmel also says that they already had in mind way back in 1999, the intention to create an eight cylinder version of the 5.0 litre V-10 S85B50 (for the M5 and M6) for the future M3. To further understand the differences between the previous and new M3’s engines, lets make some direct comparisons.
Straight away one would notice that the new M3’s engine has a 77 horsepower increase despite being lighter than the former. This is thanks to the lightweight crankcase from BMW in Landshut, aluminium cylinder heads from Hydro Aluminium in Austria and die-cast magnesium cylinder head covers from chainsaw maker Stihl. 295 pound-foot is the max torque figure, while at least 251 lb-ft of that (85%) is available from 2100rpm onwards. The V-8 has a shorter stroke than the previous M3, enabling it to attain high-revs much more willingly, limited to 8400rpm to ensure reliability. The compression ratio is set at a whooping 12.0:1, while at idle is a silent 640rpm rumbling monster.
Double or Bi VANOS continuously variable intake and exhaust cams provide a wide powerband starting low in the rev range, and does not require a high-pressure oil arrangement unlike on the V-10. The estimated 0-100km/h time for the new M3 is 4.9 seconds, which is probably a rather conservative figure based on these figures.
Although the V-10 derived S65B40 is pretty much an M5/M6 engine with 2 of its cylinders chopped-off, it’s still a true force to be reckoned with. Come to think of it, the 4.0 litre V-8 is quite like two 2.0 litre in-line 4 cylinder Mitsubishi EVO engines bolted together, but without the turbo of course. BMW spokespersons assure the public that there will never be a turbo or supercharged version from the factory. Neither will there be a hardcore racing version since the 4.0 litre capacity does not meet the current FIA class designations.
Herbert Bayerl, head of M Engine Control unit, says that the MS S65 ECU for the V-10 and MS S60 ECU for the S65B40 created by Siemens may look similar, but the V-8’s computer is enhanced to make over 200 million calculations per second. The former S54 M3’s ECU was only capable of up to 25 million calculations per second.
New lightweight individual spark coils, one per cylinder, with integrated knock/misfire sensors, made in Germany by the American company Pulse, further enhance the new M3. Both Himmel and M engine development director Herbert Vögele express that this is a major step in advancement over the 2 bolt-on 5-cylinder sensors still used in the S85 V-10. Analysing misfire upon individual cylinders eliminate knocking and uncomplicated onboard diagnostics. The 8 units combined are also lighter than both sets of sensor panels on the M5 and M6.
Due to its shorter length than the V-10 and straight-6, the V-8 is placed further back in the engine bay, behind the front axle with 2 actual mounting points. The new M3 uses a 2 piece wet-sump arrangement, with a small sump forward of the front axle subframe, and a larger sump towards the rear. Only 2 oil pumps are used, unlike the V-10’s 3 pumps. 10.5 litres of Castrol 10W60 is used from the factory, whereas only 8.8 litres of engine oil will be required during oil and filter changes.
The ‘Efficient Dynamics’ philosophy is also reflected in the power supply, as the alternator is disconnected form charging the battery during accelerating and braking to heighten fuel and power efficiency. Journalist report that the BMW M testing division uses the same setup employed by F1 teams in endurance and stress testing. In the name of science, the unlimited S65 V-8 achieved a top speed of 294 km/h, compared to the set speed-cut at 250 km/h on the production car.
A dual DSG clutch replaces the SMG transmission, and a 6-speed manual, rear-wheel drive setup is incorporated, similar to the V-8 testing bench pictured here. Just how good the drive feel will be and how this German brute performs, can only be expected after the official launch in a few months time.
Well, 420bhp was refering to UK metric hp (4500kg-m/min) not the US imperial hp (550ft-lb/sec or 745.5watt), my mistake for not being specific.
But then again, if I was pedantic, I would say that there are also bound to be minor differences in horsepower ratings using fuels of different octanes from different countries, air intake temperatures, and etc... the list goes on.
Needless to say, there is speculation about a future 2nd and 3rd gen V-8 M3 of even greater outputs, towards the 500 hp mark.
Emm...it'll probably need another 80bhp and it'll also have to go on a serious diet to compete with the likes of the F430.
It is inevitable that the new M3 would sport a 4.0 V8 with the way things are going in the automotive industry. Everything gets bigger and heavier (thanks to more equipment and electronic gubbins) and thus the need for more power. Not to mention the Audi's RS4 already sports a kickass V8 of their own, so BMW needs an answer.
No point for a V6 either as they have already got a better alternative in their famed straight 6s.