The turbo is now present in all M models. The tradition of M has always decidedly been towards free-breathing engines. How is the change justified?
Nitschke: For us at M GmbH we had long the principle that the only true sports engine must be a NA engine, especially from reasons of power delivery and the throttle response. The famous “turbo push” was although always considered good for pure acceleration, but the sensitive response of the engine when cornering was just always a deficit - because of the turbo lag. When one on the development of Turbo technology over the last five or six years considered, you can not ignore that a lot has happened. The success of the new turbo engine in the M3 / M4 is the maximum by dethrottling the intake and exhaust paths. In addition, the material development played a role, because the hotter the turbo we can act on, the better the efficiency. We drive today Turbo temperatures well over 1000 degrees C, so that not only the efficiency gigantic improved, but also the consumption.
Together with new developments, with the airflow in the turbine or the turbine geometry itself were both the classical turbo lag as well as the brutal “turbo push” of earlier days strongly smoothed.
In sum, the disadvantages of the turbo engines are increasingly eliminated, which now allows us, the advantages of the turbo use even better. So we reach a large spread over the entire speed range
- Much torque below, very good peak power above.
You did consider a NA engine for the current M5 and M6?
Nitschke: That's right, we had the ten cylinders in the pre-development still further developed, also for displacement, that was a really fascinating engine.
After a careful comparison concept, the particular potential for the future into account, we chose the V8 engine with the turbo in the hot V and the cross-bank exhaust manifolds. Here were the same reasons as in M3 and M4 crucial: the large spread across the rev range and especially the fact that we now have Torque in new dimensions, which has helped.
What role have the cost played in choosing the turbo engine?
Nitschke: The basic architecture of the current M engines comes from BMW AG, to utilize the existing production processes, but all performance relevant and formative character components, the complete component development and the coordination and decisions take place in the home with us:
The M GmbH has the location Preußenstraße more than 100 engine developers who develop the M engines from scratch. But the costs have in the end for the engine of M5 and M6 not tipped the scale: The development of the V10-engine would not be more expensive to develop into this performance area than the V8 turbo engine was.
Put it briefly, you have replaced the naturally aspirated engine through a combination of turbocharging and high-speed engine?
Nitschke: That's right, the I6 in the M3 / M4 rotates, for example 7600 / min, which for use on the race track and for an emotional driving experience is very satisfying. Turbocharging is optimal for everyday use, the high rpm concept is optimal for the race track and driving pleasure.
Is the naturally aspirated engine now de facto dead?
Nitschke: The challenge of naturally aspirated is compliance with legal rules as for consumption and emission. Thanks to BMW TwinPower Turbo technology maximum torque is already at very low rpm. The consumption advantages over conventional naturally aspirated engines are significant. The development of naturally aspirated engines for the high-performance segment, is with regard to aspects such as approval for road use and for taxation not making any sense anymore. That's why I believe that the NA engine will be limited to the true exotics. I firmly believe: There is no way around a turbo engine today.
Asked polemically: Does this mean that all the engines for the future will be of a very similar character, because your competitors also face the same problems?
Nitschke: The direction of the BMW M GmbH in this area is surely the combination of turbocharging and high-speed concept, that’s where we see our USP (Unique Selling Proposition), which differentiates us from the competition. The wide usable rev range distinguishes us, it will remain so, and we are planning our lead here in the future also to expand. The use of the twin-clutch transmission we will also expand in the future.
Will the I6 engine be kept as a USP for the small series?
Nitschke: I can definitely confirm that! We have made a lot of concept studies, for example V-engines considered which has an advantage in the length. But first we have no problems with weight balance of the cars, and secondly, the I6 is an icon of M brand - and that will remain so also in the long term.
What about the development of engine capacity?
Nitschke: We at BMW have found that the optimal single cylinder size is 500 cubic centimeters for inline engines. Starting from this philosophy are the displacements in the
Modular system clearly defined, then the six-cylinder in three liters displacement, the four-cylinder with two liters displacement and the three-cylinder at 1, 5 Liters. The lower limit for the single cylinder volume is 400 cubic centimeters, the defined room for maneuver. theoretically would then be the six-cylinder as lower limit of 2.4 liters conceivable, but we have found that the effects in the C02 emissions will be less and less.
How does the legislation in general influence engine development?
Nitschke: In the sport motors quite strong, because by new laws the areas of injection and cooling has become even more central. The expected legislation for more wide-spread consumption driving cycles sets the engine developers with great challenges, because the engine over greater rpm/load variations than before have to operate in emissions optimal conditions (if you continued good cycle consumption wants to achieve). To gain more leeway, you will tend to move towards more displacement.
The sound of the engine plays a central role. The turbo muffles sound, which has also been criticized in M3 and M4. What response do you have to the whiners?
Nitschke: The theme of sound is in the specifications strongly prioritized. The new M3 / M4 has its very special and unique sound character. We have looked at everything on available technologies, for instance active Sound Design with outdoor speakers. We have decided that this technology is not yet mature for the performance segment and that our customers expect another experience. About the valve control in the exhaust we have found a good solution. We help with the cabin engine noise somewhat, because we believe that the driver should have a acoustic feedback to the load condition and rpm of the engine.
You have stated that dual-clutch transmission are set because of the high-speed concept.
What about the manual transmission?
Nitschke: In Europe, the taking order for the manual transmission decreased significantly,
here we are, for example, in M3 / M4 in the range of 20 percent. Today the DCT and automatic gives better performance figures than the manual transmission, which for us in certain way is a small dilemma. But there is of course a hardcore community, for which the MT is mandatory. What I can promise is that the combination of six-cylinder and manual transmission is maintained as a long-term option, which also makes sense from weight reasons because the MT is about 30 kg lighter. In addition, we believe that the manual gearbox perhaps even again could become a USP - based on the competition. In the V8 this is currently still a moving target, since particularly the American market the demands a MT.
But it is also clear that this solution represents a second build line, and a second transmission supplier, and a separate setup, which also is cost relevant.
The ratio spread of gear is often used to save fuel. Many fans criticize that. How do you feel about the topic?
Nitschke: Since we have at the M GmbH a clear philosophy: In top gear the M3 and M4 reach it’s maximum speed, the seventh gear is therefore a driving gear and no overdrive. What consumption or NEDC (New European Driving Cycle) is concerned, the transmission shift points are important. Also, we observe that the competition in start up mode often selects a shift strategy with an extremely low rpm level which requires a corresponding driving style. This usually leads to the driver always choosing the Sport settings. We don’t want to employ this strategy on our customers, even though our settings might lead to a slightly higher cycle consumption.
How does M GmbH handle FWD in the long term, because the UKL platform with front-wheel drive is indeed around the corner?
Nitschke: Our clear message is that for the foreseeable future, no M with front wheel drive will be made. I know from the Mini-project exactly what HP and torque transfer limits there is to the front wheels, and these physical limits seem to me to be too low for an M model.
But in the long term are still 1- and 2-series on the UKL platform, right?
Nitschke: This is not said so. It is in foreseeable future of M no 2-series BMW M with front-wheel drive, that I can rule out. An M-model with pure front-wheel drive I can also exclude. I will even go one step further: I also exclude M-models with a front-biased AWD. This is for us from dynamic aspects not an option. The decision whether the 2 and the next 1 share the same platform, incidentally, has only be taken.
One could get the impression that the rear-wheel drive sports segment is on the decline and the four wheel drive on the rise. What is M GmbH doing?
Nitschke: In the M3 / M4 we will remain faithful in the long-term to rear-wheel drive, this also applies generally for everything ranging up to a maximum of 600 Nm. Spoken on a general basis I think it makes more sense, to focus on a move towards weight reduction, instead of putting more and more power while at the same time constantly increasing weight in the vehicles.
Are all-wheel drive systems conceivable under sports terms?
Nitschke: Many of the AWD wheel drive systems are not optimal for us. Turn in understeer or understeer through the curve is not something that the M-models has been known to communicate. We have already AWD experience in the performance segment, for example, on the X5 M and X6 M. It would in future the possibility M5 / M6 also optional with AWD. But this would be extremely rear-biased, more as a sport AWD than a traction AWD, perhaps even in combination with rear wheel steering. The RWD option would also remain for the M5/M6.
Lightweight has a strong history in the M GmbH, but you are also dependent on the general weight spiral. There is actually no M-models more under 1500-1600kg now. How do you want to stop this trend?
Nitschke: The weight issue is for us unquestionably a great balancing act. In M3 / M4 and M5 / M6 we made it after all, that the M models are not heavier than the base, which is not so easy because our cars have larger brakes, larger wheels, more elaborate gear, race track suitable cooling systems, larger engines or additional reinforcements. The weight issue is now the most critical job, because our goal in the future consists in the weight compared to the starting material further reducing. High weight can be offset by high-power, but the rule only applies to the longitudinal dynamics. For handling, transverse momentum or the brakes high weight is a problem.
Will there be a GTS model based from the M3, and if so, when?
Nitschke: We have some good ideas there, and the special topic models under the M-label has worked very well, as the past has proven. And BMW celebrates in 2016 a birthday, and we at M GmbH will probably celebrate as well…
What is missing in the portfolio of M GmbH, is a classic two-seat sports car. Audi has one, Mercedes has one. Why not BMW?
Nitschke: BMW has decided not to build classic sports car, but a pioneer, as also the M1was, one which should also point to the future. And this car is called i8. Although it is not of the M, but we all have a huge amount learned from that car. If we in the future should go towards a M-supersportscar, then that would be something special, and not just another supersportscar.
Wouldn’t a true sports car help to reinforce the sportiness of the brand?
Nitschke: Unlike Mercedes and Audi we have the sporty image no problem, since all the polls say the same thing. BMW stands for Sport and dynamics, we do not need to prove this with a traditional sports car. The need simply is not there at BMW. For BMW AG that is in one part lucky, for M GmbH certainly this is partly bad luck, because of course we would like to have such a project to make and promote. Now that the i8 is there, this train has departed for us.
Would it be completely excluded that M GmbH makes a sports model of the i8?
Nitschke: This question is one everyone asks, from the moment the first photos of the i8 appeared. For this purpose, one must know that the i-Brand and M GmbH, represents the two “book supports” at the opposing ends of the BMW brand, we call this the “Bookend strategy”. i and M are as two poles of the left and right of the brand BMW: this means that-we pursue very different goals and very different customer needs with an extreme spread between us.
All right. So no M i8. What about the hybridization of M-models? Is this possible?
Nitschke: If the total character of the vehicle does not suffer by the hybridisation, then it is acceptable. An electric motor has have something fascinating, because it makesthe highest torque from standstill. Hence for engineers a combination of combustion and E-motor is an attractive approach. The M-point of the question is: What do I have to add on system weights, to be able to operate both? When I to the customer ultimately must say that I added hundreds of kilos of batteries into the car, to feed an electric motor with 90 kW, and improve acceleration by two-tenths, but the handling on the Nordschleife has been compromised and that the balance of the overall concept suffers - This would our customers not accept.
