A few years ago I was in email communication with a reader. We were having a debate about a particular automotive topic and he kept using the word 'lambda' in the wrong way. When I pointed this out, he replied that a workshop proprietor had told him what it meant - and if a proper mechanic didn't know the word's meaning, who would? That rejoinder made me stop and ponder for a moment - why was I so confident that I was right and he was wrong? Then I realised - my definition had come from the best automotive engineering reference in the world, the Bosch Automotive Handbook. Back then I would have been using the Third Edition - and now Bosch has just released a new Fifth Edition.
Without a doubt, the Automotive Handbook is the most widely used, authoritative and extensive engineering resource available on automotive topics. There are few engineers working in car companies that don't have a copy of it on their shelves, and for the serious enthusiast, it is simply a must-have.
So what's actually in this Bible? Just Bosch stuff?
The small format softcover (180 x 120mm) has no less than 962 very thin pages containing literally dozens of chapters. However, the content can be subdivided into two main classes - general reference material, and detailed discussion of topics close to the Bosch company's heart. The general reference material is similar to that which can be found in other engineering sourcebooks - with one significant difference: it's all automotive based. So, for example, there are chapters on Physics, Mathematics, Materials, Machine Parts, Joining and Bonding Techniques, Sheet Metal Processing, and Tribology (the study of lubricants).
But that listing tells you little - so let's explore just the Physics chapter. Within this there are sections on units (including definitions and conversions), equations relating all manner of things automotive (from acceleration to cornering), acoustic engineering, electronics theory and practice - it goes on and on. In fact, in just the first 90 pages there's the same amount of info that you'd normally find in a full book. But that first chapter isn't finished yet - there are also major sections on sensors and actuators. So if you want to know precisely how oxygen sensors, crank-angle sensors, yaw sensors, windscreen rain sensors (etc!) work, this book clearly and succinctly explains their operation. It's right up to date and absolutely authoritative.
Other major reference chapters include those on emissions, theory of internal combustion engines, chassis systems, engine air supply, and engine cooling.
Three points should be made. The book is aimed at engineers, and so the language used often isn't all that simple. Secondly, a huge amount of information is crammed into every sentence and so some will need to be read several times for the full implications to become clear. Finally, no photos are used - just superbly drawn, detailed diagrams.
So what is actually said about different topics? Here's an extract on the hot-wire air-mass meter:
"Air-mass meters operate according to the hot-wire or hot-film principle; the unit contains no moving mechanical parts. The closed-loop control circuit in the meter's housing maintains a constant temperature differential between a fine platinum wire or thin-film resistor and the passing air stream. The current required for heating provides an extremely precise - albeit non-linear - index of mass air flow. The system's ECU generally converts the signals into linear form as well as assuming other signal-processing duties. Due to its closed-loop design, this type of air-mass meter can monitor flow rate variations in the millisecond range. However, the sensor's inability to recognize flow direction can produce substantial measuring errors when strong pulsation occurs in the manifold.
"The platinum wire in the hot-wire air-mass meter functions both as the heating element and as the heating element's temperature sensor. To ensure stable and reliable performance throughout an extended service life, the system must burn-off all accumulated deposits from the hot-wire's surface (at approx. 1000&°;C) after each phase of active operation (when the ignition is switched off).
"The hot-film air-mass meter combines all measuring elements and the control electronics on a single substrate. In current versions, the heating resistor is located on the back of the base wafer, with the corresponding temperature sensor on the front. This results in somewhat greater response lag than that associated with the hot-wire meter."
So, did you know that a hot-wire meter can be upset by manifold pulsing? Did you know that the now more common hot film sensor is slower reacting than the older hot-wire? There's barely a paragraph anywhere in the book where even an expert won't learn something new...
Also in the reference vein, there is also a heap of information on materials that's near impossible to find elsewhere. Let's just take fuels, for example. (We could as easily have taken Metals, or Ceramics, or Plastics - it's all there.) Want to know what the density, latent heat of evaporation, ignition temperature and chemical constituents are for petrol, aviation fuel, kerosene, acetone, ether - and a whole lot of others? Well, you'll find it here, along with the same info for all the combustible gases as well!
The second half of the book explores the theory and execution of the myriad of Bosch systems. Each of the Bosch engine management systems is covered - from ME-Motronic back to K-Jetronic. Each coverage includes a system diagram, discussion of operation, and drawings of specific sensors. The engineering rationale behind the approach that has been taken is also explored, and this normally involves an extensive background coverage. So the book discusses the operation of ABS - but also backgrounds control theory, frictional co-efficients of tyres on roads, braking system make-up, braking efficiencies, driver reaction times and so on. Basically, just the section on brakes becomes a handbook in its own right. New in the latest edition is an extensive coverage of Electronic Stability Program (ESP), although this material is presented at an engineering physics level, with lots of equations.
So what's bad about the book? Not much - although it is a bit Euro-centric (the example drawing of a rotary engine is from the ancient NSU Ro80 - the engine that sent the company broke...one would think that a Mazda rotary might be a more fitting inclusion!) and at times the depth of treatment varies. Navigation systems, for example, are covered quite poorly - I assume that Bosch doesn't produce a nav system.
This also probably isn't a book for absolute beginners interested in modifying cars. There's nothing at all on making cars go faster, and while there are certainly sections appropriate for newcomers, the rest of the book's complexity may be a bit off-putting to someone just starting off an automotive interest.
But together with a modern book on modifying cars, the Bosch Automotive Handbook will provide you with a resource that is literally second to none. If you're intensely interested in how cars work, the purchase price of the book is money very well spent. And let me put it this way - if every car enthusiast contributing to web discussions had a copy of this book in their hands, the level of debate would go up enormously!
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