|
 |
 |
 |
 |
 |
 |
 |
 |
| ||||
|
Fundamental parameters of an engine, Part 1/3
What is torque ? What is the relationship between torque and power ? How to compare the flexibility and the operating range of two different engines ? What represents the maximum torque and the rpm at which it occurs ? What happens if the engine is exploited at full load below its revs of maximum torque ? What are the variables which make it possible to calculate the power developed by an engine ? The first part of this file will guide you step by step towards the comprehension of the fundamental principles which rule the driving characteristics of our cars' engines. Publication date : April 2004. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
|
Fundamental parameters of an engine, Part 2/3
What is the influence of the number of cylinders on the performances ? Why are the dimensions of bore and stroke, which determine the displacement, a compromise ? What are the parameters influencing the performance characteristics of an engine ? The second part of this file will guide you step by step towards the comprehension of the fundamental parameters ruling the architecture of the automotive engine. Publication date : April 2004. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
|
Fundamental parameters of an engine, Part 3/3
What exactly is the thermal efficiency? What relation has it with the specific fuel consumption? Which are the advantages and the respective drawbacks of in-line, V and opposite cylinders engines? Is there an optimal number of cylinders in function of a required power ? In the third part of this file, we have a look at the compromise designers have to face and we also examine the parameters which influence engine efficiency, balance and smooth running. Publication date : May 2004. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
| ||||
|
Supercharging and turbocharging
The power of a reciprocating internal combustion engine can be increased in vast proportions by charging it with air compressed above the atmospheric pressure. That may be done by various compressor types, but their drive takes some power which is subtracted from the brut engine's power if the compressor is mechanically driven from the crankshaft. By driving a high speed axial or radial compressor with an exhaust gas turbine, some energy that would otherwise be lost is recovered to drive the compressor. A vast array of combinations and associations of turbo-machinery and mechanical compressors have been imagined and developed. More are coming… Publication date : November 2003.
Access by securized micro-payment system or Credit Card Document access. | |||
|
Turbocharging and turbocompounding
Turbochargers are dynamic compressors driven by an exhaust gas turbine. Several variants of turbocharging have been developed, first for aircraft and marine engines and since some decades for automotive applications as well: constant pressure, pulse, 2-stage, regulated 2-stage, waste-gated, sequential, variable geometry turbine inlet. Exhaust gas turbines recover a fraction of the energy lost in the exhaust and are a convenient means to drive a high speed dynamic compressor. Else, the turbine's power can be harnessed and transmitted to the crankshaft by the process know as turbocompounding. Publication date : December 2003. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
|
A 2-stage turbocharged diesel from Opel
Even if the Opel Vectra OPC remains a prototype, its engine precedes the next generation of turbocharged automotive diesels. Thanks to a cleverly designed 2-stage sequential turbocharging system, a power of 156 kW (210 hp) and an extremely high torque of 400 Nm over a large rpm range have been obtained… from a 1.9 liters diesel ! Publication date : April 2004.
Source : Opel. Access by securized micro-payment system or Credit Card Document access. | |||
|
Two-stage sequential turbocharging for the BMW 535d
This fall, BMW will be the first OEM to commercialize a 2-stage turbocharged automotive diesel. This engine is an evolution of the well known and proven 3-liter straight-6 diesel whose power has recently been increased from 135 to 160 kW (215 hp). The new version develops 200 kW (268 hp, about 90 hp per liter!), which position it in direct competition with the most powerful V8s diesels of the market, in particular the recent V8 4.0 TDI of Audi and, of course, the V8 of the 740d. Publication date : July 2004.
Author : François Dovat
Access by securized micro-payment system or Credit Card
Document access. | |||
|
Supercharging
The amount of combustion air supplied to the spark ignited and diesel engines, and thus their power output, can be largely increased by boosting the charge air pressure. This is achieved by the use of compressors driven either from the engine's crankshaft, an exhaust gas turbine, a slave motor, or a combination of these different means. Publication date : February 2004. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
| ||||
|
Gasoline direct injection systems
Gasoline direct injection (GDI) looks somewhat like the 42 volts or stop-start systems sagas: even if these technologies show some obvious benefits, their production has been delayed for various reasons or has met some setbacks. However, gasoline direct injection is far from being a new concept since the first applications appeared in Germany in 1937 on aircraft engines and in 1952 on automotive engines. After several attempts, this technology seems now quite mature enough for mass production, either on reliability, fuel economy, CO2 and pollutants emissions or on range of operation standpoints. Up to now, the Volkswagen Group offers the most extensive choice of direct injection engines, but Lexus, BMW and Mercedes present rather more imaginative or advanced ways such as dual injectors or piezoelectric technologies. Due to the technical and thermodynamical reasons exposed below, it can be safely assumed that GDI is intrinsically an essential part of up to date and future downsized and turbocharged spark ignition engines. Although higher production costs hinder at the moment a broader marketing, almost all the OEMs have gasoline direct injection engines in development. Publication date : May 2008.
Access by securized micro-payment system or Credit Card Document access. | |||
|
Diesel fuel injection systems
If the turbocharged diesel engine is the favorite of more and more Europeans, it is mainly due to the remarkable and amazing recent developments of the fuel injection equipments. Some types can generate an injection pressure exceeding the water pressure at a depth of 20'000 meters, much deeper than the Mariana Trench - which is the world's deepest ocean bottom at 11'035 m. The common rail injectors and electronic control systems of the latest generation are also able to perform up to 5 separate injections per cycle, with timing intervals of 4/10'000 seconds. We have shifted from several decades of almost stagnation to an flood of enhancements ever since the arrival of electronic regulation and direct injection on small automotive diesels. Their development is far from being over. Publication date : February 2004.
Access by securized micro-payment system or Credit Card Document access. | |||
| ||||
|
New Mercedes-Benz C 320 CDI (OM 642): a light, compact and powerfull V6 Diesel
After a development and testing period of approximately 40 months, a new 3-liter V6 CDI engine is entering series production and supersedes the 5 and 6 inline diesels of Mercedes-Benz. The new OM 642 incorporates all the up-to-date technologies in diesel engine development – from the mechanical system and thermal/flow dynamics to the electronic engine management and emissions control. It weights 208 kg only, roughly the weight of the former inline 5 and about 12 kg less than the Audi V6 TDI of the same power but with a lower torque back up. Moreover, a prototype version with 2-stage sequential turbocharging by 3 turbochargers has been partly unveiled at the Geneva Motor Show and will most probably be commercialized soon. Publication date : April 2005. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. Sources : DaimlerChrysler, Hydro aluminium. | |||
|
Future BMW - PSA 1600 engines :Valvetronic… or turbocharging and direct injection
BMW and PSA Peugeot-Citroën have joined their know-how to design a 1.6 liter spark ignition engine intended to replace, amongst others, the Mini's "Pentagon" made in Brazil under a joint venture of BMW-Chrysler - the later having become DaimlerChrysler. The new 4 cylinder will be initially produced in two version, one equipped with the famous Valvetronic continuously variable valve lift and opening duration system, the other being fitted with direct injection and a twin scroll turbocharger. Various versions with power spreading from 55 kW/ 75 hp to 125 kW/170 hp will appear later on. A small turbocharged engine offering a significant advantage in terms of weight and fuel economy in comparison with a naturally aspirated engine of larger displacement, the 1600 Turbo will substitute to bigger naturally aspirated engines in high performance cars as well as in compact and middle range cars of PSA Peugeot Citroen. It will be manufactured in the PSA factory at Douvrin (Pas-de-Calais) where the production line is planned for a capacity of 2500 units per day. Publication date : January 2005. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. Source : PSA and BMW. | |||
|
The Chrysler New Hemi : a cost-efficient engine
The new Hemi associates well known, proven and cost effective concepts with modern technology. In the spring of 2005, a 6.1-liter / 425 hp version will be available on the Chrysler 300C SRT8. The advantage of overhead camshafts due to reduced valvetrain inertia and deflection emerges at high rpm. But soaring revs are of no use nowadays on a street engine, so that a single camshaft-in-block is absolutely adequate, as well as two valves only per cylinder. The hemispherical combustion chamber favorable surface to volume ratio and breathing ability can be exploited without overhead camshafts cost and complexity, making manufacture, servicing and repairs easier and less costly. Apart of aircraft engines where dual ignition is mandatory for safety reasons, twin spark ignition was largely used on racing engines of the fifties and sixties, especially those of Maserati and Porsche. Alfa-Romeo also fitted it to some production engines such as the GTA and 2-liter "Twin Spark". It allows a faster burn rate, particularly on over-square engines and leaves more space for large valves than a centrally located single spark plug. Furthermore, with a domed piston and a single plug, flame front shrouding may lower the burn rates. This problem is avoided with dual spark ignition. The New Hemi features both twin spark ignition and single camshaft. Its latest variant develops as much as 425 hp, right out of the factory. Publication date : December 2004. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
|
VR5, VR6, W8, W12 and W16 : audacious engine concepts by VAG
Launched in 1991, the unorthodox VR 6 associates the characteristics of in-line and V engines - thus the initial designation of "VR", which stands for V - Reihe (vee-line). A compact design well adapted to transverse engine layout was obtained by this singular concept. From 2001 on, a whole line of successors with even weirder cylinder arrangement was launched. Indeed, the engineers had not brought the development to a dead end with such a technical creativity: they subsequently dared a unique configuration: the W8, W12 and even W16 engines. Publication date : November 2003. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
|
Mercedes 3.5 V6 engine
For its latest V6 at 90°, Mercedes-Benz gave up the previously much self-praised concept of 3 valves per cylinder and dual ignition! The new V6 with light alloy crankcase and cylinder heads has 4 valves per cylinder (in 28.5° V), 4 overhead camshafts fitted with continuously variable timing adjustment devices, two-length intake runners with additional tumble flaps, and an electronically controlled thermostat. Publication date : March 2004. Source : Mercedes-Benz.
Access by securized micro-payment system or Credit Card Document access. | |||
| ||||
|
A Comparative study of New Automotive Vee-Format Diesel Engines
Faced with the exhaustion of mineral oils and the potentially catastrophic increase of the CO2 proportion in the atmosphere, our civilization has hardly any other realistic choice in the short run but to limit fuel oil consumption, in particular by adopting thermal engines with an efficiency as high as possible. The Diesel engine remains today the thermal engine with the highest efficiency. Moreover, it can work with vegetable oils - or at least mixed with fuel oil. Its toxic emissions, in particular nitrogen oxides and soot, have been radically reduced, thanks to particulate filters and specific NOx and oxidation catalysts. Also not to be overlooked are the continuous improvements being made to the diesel combustion process, which contribute to the lower engine-out emissions. Publication date : July 2004. Author : François Dovat
Access by securized micro-payment system or Credit Card Document access. | |||
