Monday 25 October 2021

M xDrive Intro

One of the biggest changes in the F90 M5 was the introduction of a 4-wheel-drive system. This change was greeted with a lot of trepidation from the community because 4WD had a history of poor handling. However, because of the difficulty of getting the M5's torque to the road, and because of competitors who were smashing BMW's 0-60 times with 4WD, BMW was forced to follow suit.

As I explained in Horsepower:

In practice, 1g of acceleration (+22 mph per second) would never happen with the M5 because its road tires just aren’t that sticky. Generally a good rule of thumb for a decent road tire is that it can push forward with about the same force as the weight pushing down on it.

Since the M5 is a rear wheel drive car, and about half the weight of the car is on the rear wheels, it can only accelerate at about 0.5g to start. It gets a bit better than this in practice because as the rear wheels start accelerating, the weight goes more onto the back wheels resulting in an effective acceleration of about 0.7 g’s (about +15 mph per second) with good tires on good pavement.

The above implies that regardless of how powerful the engine, no 2-wheel drive car with 50-50 weight distribution can accelerate to 60 faster than in about 4s on road tires. However, with 4WD with road tires on a good surface, a car could achieve 1g of acceleration if the engine is powerful enough (2.7s to 60). Because the F90 M5 engine can't quite generate 1g of acceleration in 2nd gear (more like 0.9g), and you have to shift to 2nd at around 30mph, in practice it's about 3s to 60.

While 0-60 is the most visible metric dramatically impacted by 4WD, acceleration out of corners is also improved with BMW's M 4WD. This is because the traction of the tires is divided between turning and accelerating. If you put too much torque into a RWD car while turning, it will spin out ("oversteer"). If too much torque on a FWD car, it will not turn in ("understeer"). If you divide the acceleration amongst all 4 tires, the total acceleration available from all tires out of a turn can be more given the same traction available for turning on both front and rear tires.

This last point is crucial to the development of the 4WD system on the M cars (called "M xDrive"). The M xDrive can actively direct torque between front wheels and the rear right and rear left wheels. So during turning the system can exactly provide torque to where it's needed at any given moment in time in order to optimize the handling (which was the big bugaboo with 4WD systems in the past).

Quoting from the BMW site 5 Facts about M xDrive:

[The system] monitors real-time parameters from the accelerator pedal position, steering angle, road speed, slip at the front and rear axle, longitudinal and transverse acceleration, friction coefficient, yaw rate, etc. This information is analysed to establish the vehicle’s current situation. M xDrive can then support the driver in every set of circumstances.

When accelerating out of a bend, M xDrive successively puts more and more torque on the front axle when it detects decreasing lateral acceleration. At that moment, it becomes possible to transmit the longitudinal forces without understeering. This occurs so gradually that it’s possible to exit the bend with a slight drift, as one would expect from an M automobile. It feels as if you are coming out of the curve in a controlled catapult.

From my test drive of the car, I can tell you that this absolutely is a real thing and puts a huge smile on your face even in regular road driving. I was instantly sold! The faster 0-60 is a bonus.

We'll get into the development and the technical details in follow-up blog posts.

Thursday 21 October 2021

Introduction to the F90

 In this post I'll give an introduction to the car I ordered: the 2022 BMW F90 LCI M5 Competition.

The designator "F90" is an internal BMW chassis designator. Originally the chassis designators all started with the letter "E" which stands for the German word "Entwicklung" which means "Development". BMW ran out of two-digit designators and moved into "F" and now "G". The designators are handed out once development begins. So we can conclude that work on the F90 (M5) began before work on the G30 (the regular 5-series) or even the G12 (the latest 7-series on which aspects of the latest 5-series is based).

For a history of BMW, see History of BMW.

For a history of the 5-series, see 5-Series History.

For a history of the M cars, see History of "M" and M5.

The G30 was unveiled in October 2016 and the F90 in September 2017.

Usually the M5's have the same chassis designator as the regular 5-series, but not this time. This is apparently because work on the next generation M5 began before the work on the new 5-Series, whereas usually it is the opposite, although in the end many of the elements are merged.

This car is the LCI, meaning "Lifecycle Impulse", a collection of minor changes and improvements midway through a car's lifecycle. The LCI was released for the 2021 model year.

The F90 is an incremental improvement off the previous generation F10 M5, using essentially the same engine (although further developed). Big differences are

  • the introduction of 4-wheel drive (M xDrive)
  • a significant increase in torque and horsepower
  • a lighter and stiffer chassis
  • the adoption of an automatic transmission
  • the adoption of an electric power steering system (M EPS)
  • a complete update of the vehicle electronics

This generation of 5-series comes in multiple engine styles and performance levels as follows.

  • 530i - B46 turbo 4-cylinder / 248 HP / 295 lb-ft
  • 530e - B46 turbo (detuned for fuel economy) + hybrid electric / 248 HP / 310 lb-ft
  • 530d - 6-cylinder diesel / 261 HP / 461 lb-ft
  • 540i - B58 turbo 6 cylinder / 335 HP / 332 lb-ft
  • M550i - N63TU2 turbo 8 cylinder/ 455 HP / 480 lb-ft
  • M5 - S63TU4 turbo 8 cylinder / 600HP / 553 lb-ft
  • M5 Competition - S63TU4 turbo 8 cylinder / 617HP / 553 lb-ft
  • M5 CS - S63TU4 turbo 8 cylinder / 635HP / 553 lb-ft

The M cars have a different engine, beefed up components to deal with the power and torque, different steering, and a more rigid chassis.

In the next few posts we'll cover off the big changes from the F10 M5 (the car you can read all about in the earlier part of this blog).

Wednesday 29 September 2021

BMW Technical Information

The very best source for technical information about BMW cars is the BMW TIS (Technical Information System).

https://www.bmwtis.com

You only really need a single day's access for $30, and that allows you to go into the training section and download literally any of the pdf documents that are in there (about 180 or so). It's wise to cast a broader net, as a document about your car may refer to other documents.

This is what I downloaded that day for my $30:

But don't worry, if you're interested in the BMW F90 LSI M5 Competition, I'm doing all the reading for you and will present my synthesis on this blog. The previous generation F10 M5 was similar in many ways to the current generation F90, so if you're interested in the F90, best to go back to the start of this blog and read through it to catch up to me. Also, all the history and basic car engineering principles are the same, so good to read that as well.

As I go through the new car, I will explicitly refer back to earlier blog entries and then carry on with the differences, so nothing lost if you want to prepare yourself.

New Car Ordered

 I just ordered a new M5 and so... I'm back!

This will be my third BMW. I started with the 2005 E60 BMW 545i:

2005 E60 545i. RWD V8, 3748lbs, 330lb-ft@3600rpm, 0-100 in 5.8s; 325 HP

I was considering an M5 at the time, but it was a big naturally aspirated  V10 engine with an SMG transmission that I did not like, so I went with the much more practical and drivable 545i. It was a great car and did not give me a lick of trouble the whole time.

In the 2011 model year BMW launched the F10 M5. It corrected all the flaws with the previous M5 and so I stepped up to a 2013 model year M5.

2013 F10 M5. RWD turbo V8, 4387lbs, 501ft-lbs@1500rpm, 0-100 in 3.9s, 560 HP

I stuck with the blue because I really liked the blue. It was the first turbo-charged V8 from BMW and had a paddle-shifted Dual-Clutch Transmission which was absolutely brilliant. The torque was magnificent and available at from low RPM right up to screeching RPM. It has also been very trouble-free over the years (except it used a lot of engine oil, by design). Only recently they noticed the engine leaking oil in a way it ought not to be, which necessitated a gasket job, which was pricey and off warranty. I thought maybe this was the beginning of the end for me for this car, going onto 9 years, and there had been a new generation of M5 introduced in 2017 that I was wanting to get into, so I recently pulled the trigger and put in my order.

2022 F90 LCI M5 Competition. 4WD turbo V8, 4370lbs, 553ft-lbs@1800rpm, 0-100 in 3.2s, 617 HP

The M5 now comes in three variants, the base M5 (not available in Canada), the M5 Competition, and the M5 CS. The CS raises horsepower (though not torque) and lightens the car with more carbon fiber, especially the seats. It also has a considerably rougher ride and is much more expensive as a "limited edition". So the M5 Competition was my variant of choice.

The "LCI" stands for "Lifecycle Impulse" and is BMW's new word for a midcycle refresh. That was done for the 2021 model year, and there are some important upgrades which I will get into later, which made it more attractive.

I went with the "Ultimate Package" which has most of the bells and whistles. The colour is "Aventurine Red Metallic" and the interior is "Tartufo Brown Full Merion Leather".

It should arrive before March, so I'm looking forward to that!

Friday 15 March 2013

Black Panel Display

The M5's instrument cluster is a combination of dials, fixed lights, and a panel. It is all overlaid with "Black Panel Technology" from BMW, Bayer Material Science, and other partners that uses Marnot XL GU 90 polycarbonate films that has a black, matt, completely homogeneous surface when the displays hidden behind them are not activated.



The lower black are cutting across the speedometer and tachometer is the pixel display. Everywhere else there are the traditional hardwired LED lamps, but because of the black panel technology it is difficult to see them when not lit.


This is the display when lit. the "Park" for example is a standard LED . The big "P" beneath it, and the "Efficient | Comfort | Comfort" under the tachometer are all images created on the small pixel-addressable screen.

Saturday 23 February 2013

History of BMW

BMW came out of a merger between an airplane maker and an engine maker. Leading up to and during the world wars, BMW made airplanes. Immediately after each war, they were shut down and had to shift to motorcycles first, and then cars.

The roots of the airplane maker side of BMW go back to Gustav Otto, the son of the inventor of the four stroke internal combustion engine and a pioneer aviator in Bavaria in 1910.


Otto's airplane manufacturing company "Otto Flug Maschinen Fabrik" was plagued with production problems, and was taken over by the German government and then reorganized as Bayerische Flugzeug Werke AG (BFW) in 1916 in the midst of WWI (1914-1918). They managed to solve the quality problems and were a major contributor to the war effort.

The company was hit hard after WWI, as it was forced to shut down airplane production by the allies. To survive, BFW moved into furniture and fitted kitchens using their advanced joinery factories developed to build the wooden aircraft of the time.

By 1922, taking advantage of BFW's hard times, Viennese financier Camillo Castiglioni


had acquired all the shares. At this time it also branched out into designing and building "Flink" and "Helios" brand motorcycles, with the engines supplied by a company called Bayerische Motoren Werke (BMW), for whom Castiglioni was a shareholder. 


In that same year, Castiglioni bought the rights to the name BMW, its engine designs, and its engine manufacturing capabilities and merged that with his wholly-owned aircraft manufacturing company, BFW, renaming the whole to BMW and moving it to the same buildings as previously occupied by Otto Flugzeug Werke on Lerchenauer Strasse 76, where BMW HQ has been ever since. 


Meanwhile, Rapp Motoren Werke, established in 1913, supplied Otto with his four cylinder aircraft engines. They were also subcontracted by Austro-Daimler to produce their V12 aircraft engines, a deal brokered by Castiglioni. The Austrian sent to oversee the contract, Franz Popp, became actively involved in company management, changed the name of the company to Bayerische Motoren Werke GmbH in 1916, and brought on Max Friz as the chief designer to replace Rapp. Friz designed an excellent aircraft engine, the BMW IIIa.


Not willing to continue financing the company itself anymore, The Bavarian and Prussian ministries of war encouraged BMW to be taken public in August of 1918. It was to be one third owned by Bavarian Banks, one third by Bavarian industrialist Fritz Neumeyer, and one third by Castiglioni.

At the end of WWI in November of 1918, BMW was no longer allowed to make aircraft engines by the terms of the armistice, yet the BMW IIIa was its only product. At this time, Castiglioni bought all outstanding shares, the other shareholders having lost confidence in the future of the company.

When allowed to reopen in 1919, under the guidance of Popp and Friz, BWM shifted to motorcycle and boat engines. This alone could not sustain them and Castiglioni maneuvered a contract from Knorr-Bremse of Berlin to manufacture pneumatic railway brakes (having arranged for the Bavarian government to buy their trains in exchange for having the brakes made in Bavaria). The brake building part of the venture quickly overshadowed the engine part of the business. Castiglioni sold BMW to Knorr-Bremse at a considerable profit. Under Knorr-Bremse, the company rapidly grew.

In 1922, Castiglioni offered to buy back BMW's engine-building business (including Popp as GM, Friz as Chief Designer, and all their engine-related intellectual property), and all rights to the BMW name from Knorr-Bremse, who agreed, being only interested in trains, not airplanes. This company was merged into Castiglioni's other company, Bayerische Flugzeug Werke in 1922, under the BMW name.

In the early 1920's, the modestly sized BMW Company produced motorcycles, small engines, and spare parts, and did not do very well, having not gotten back into the airplane building business since the end of WWI. However, Castiglioni had bought BMW back from Knorr-Bremse for a reason, and had in his back pocket a deal with the Czech government for the BMW IIIa and IV aircraft engines to be manufactured under license by the Walter Company of Prague. The considerable proceeds of the licensing deal went straight into Castiglioni's pocket through unscrupulous accounting practices. Consummating this deal was his true goal in acquiring back the engine division from Knorr-Bremse.

But Castiglioni was not done yet. Soon after this deal, in 1923, BMW began again producing aircraft engines, and won a major contract with the Russian Red Army brokered by Castiglioni. An illicit 10% commission on each engine sold went back into Castiglioni's pocket though shadow companies.

In 1926, Castiglioni ran into unrelated financial problems with Deutsche Bank, and had to relinquish some shares in BMW. As part owner, he was then investigated by the bank for his shady business dealings, and got into further financial difficulty, and was forced to pay back BMW for the illicit commissions which resulted in all his shares going to Deutsche Bank. The Soviets argued they had been overcharged the illicit 10% and settled for a perpetual license to the BMW VI engine design, and then ceased doing business with BMW by 1931.

As the writing was on the wall, under Popp's leadership BMW diversified into motorcycles and then cars in 1928. The Dixi Company of Eisenach licensed the British Austin Seven and began selling it in 1927. In 1928, BMW bought the Dixi Company and renamed the car to be the BMW Dixi, and then the BMW 3/15.


Wishing to wean themselves from the Austin license that was set to expire in 1932, BMW began designing and producing its own cars in 1933, with the BMW 3/20.


The successor, the BMW 303 produced in 1933, was the first BMW to sport the iconic "kidney grill" that continues to be used as a BMW design cue today.


A number of cars and motorcycles were built up to and into WWII. During the war, BWM was increasingly pressured to exclusively build aircraft engines for the Nazi's, which Popp thought a bad business to be so tied to the Nazis. By the end of the war, BMW was forced to use concentration camp labour to build jet and aircraft engines.

After the war, the company was again shut down and only emerged with its first post-war automobile in 1952. Meanwhile, an English company, Bristol, took plans for BMW's cars as war reparations, and started building Bristol Cars which were knockoffs of BMW's. BMW also had its car manufacturing in Eisenach, which was in Soviet territory. The Soviets used the plans, machinery, factories, and workforce to manufacture "BMWs" for state officials. Later on they even started exporting the cars under the BMW marque to try to get hard currency. BMW's first post-war car was the BMW 501, a luxury car costing 4x the average annual salary (in today's terms, $200,000).


These cars and the likes of the acclaimed sports car, the BMW 507 (below) were too expensive to produce, and were not commercial successes.


The company was saved in 1955 by the tiny and affordable bubble car, the Isetta, of Italian design, which married BMW's motorcycle and automobile work.


This car was popular with city dwellers, and in 1957 BMW tried to expand on the appeal of the Isetta with the unusual BMW 600.


This car was not a commercial success, but it did lay the engineering groundwork for the popular 1959 BMW 700 economy car whose success saved the company from being acquired.


This car inherited the 600's rear mounted 2 cylinder four stroke "flat-twin" engine and was BMW's last economy car until it acquired Mini.


The financial success of the 700 made up for the expensive money losing 500 series cars, but the company was still in trouble. In a famous shareholders meeting in 1959 management stressed that the 700 and their next development, the "New Class", would lead to success. Another faction wanted to essentially sell to Mercedes. In the end, a wealthy German, Herbert Quandt, acquired shares from a disgruntled shareholder and blocked the sale of the company to Mercedes. The Quandts remain as the most important shareholder to this day.

Herbert Quandt
With the new leadership at the Board, BMW was able to pursue the development of the New Class, starting with the BMW 1500 in 1962.


This car was targeted at neither the super-rich (as were the 501 and 507), nor the budget minded (as were the 600 and 700), but somewhere in between, for the affluent middle class, a market niche the BMW brand has occupied ever since. It was followed by the 1800, 1600, and 2000. All the '00' cars were four-door, and were the pre-cursors of the 5-Series. 2-door variants of these models ending in '02' were also introduced.

The new class cars used the BMW M10 engine line in production from 1962 until 1988. In its original form it was an inline 4 cylinder single overhead camshaft engine designed by former race car driver Baron Alex von Falkenhausen, displacing 1.5L and producing 80HP. In the 1500 it went from 0-60mph in 15s.

The New Class was a commercial success and established BMW as a maker of sporty, upper scale automobiles.

In 1970, Eberhard von Kuenheim was installed by the Quandts as the top manager within BMW, a position he held for nearly 25 years. von Kuenheim is credited with the idea of the "3-5-7", "small-medium-large", basic model lines which continue to exist today.


In 1972 the E12 5-Series was introduced, the "5" denoting BMW's fifth "New Class" platform.


The car was sold in various trims using inline 4 and inline 6 cylinder engines.

There followed by the E28 in 1981,


the E34 in 1988,


the E39 in 1995,


the E60 in 2003,


and finally, the latest in the series, the F10 model in 2010.


Monday 18 February 2013

Steering

The steering on the M5 uses the traditional rack and pinion method with computer-controlled hydraulic power assist.

"Rack and pinion" describes the main mechanism for moving the tie rods that themselves steer the front wheels.


The steering has a variable ratio, meaning that the rack teeth are placed closer together towards the centre and farther apart towards the outside. This means that movements of the steering wheel are "amplified" as the wheel is turned more towards lock.

All the linkages are mechanical so that the driver can feel the road through his or her hands. There is, however, a power assist that enables less effort to be put in to turn the wheel.

The basic way power steering works is that as the wheel is turned this way or that, pressurized hydraulic fluid pushes on one side of a cylinder or the other, giving the rack an extra push. The system used by BMW is from ZF Lenksystem and is called Servotronic. It provides greater steering assistance at lower speeds by using a computer.

The F10 M5 uses a new type of power steering pump called a VARIOSERV power steering pump from ZF for increased efficiency.


This uses an offset rotor, much like for the oil pump in the car, to vary the amount of oil pumped through the system depending upon need.


This means that less drag is placed on the engine when the power steering is not operating as strongly.

The Servotronic is called "M Servotronic" because the electronics are tuned specifically for the M5 and there is a button that adjusts the degree of assistance (Comfort, Sport, and SportPlus).

The complete system is shown below.



There is a dedicated hydraulic fluid cooling system for the power steering with radiator (1). The fluid reservoir is (2), the Varioserv pump (3), the Servotronic valve (4) which understands the motion of the steering wheel, and the "M" rack with its power assist cylinders (5).