KINETIC ENERGY RECOVERY SYSTEM (KERS) EXPLAINED
KERS is a collection of parts which takes some of the kinetic energy of a vehicle under deceleration, stores this energy and then releases this stored energy back into the drive train of the vehicle, providing a power boost to that vehicle. For the driver, it is like having two power sources at his disposal, one of the power sources is the engine while the other is the stored kinetic energy. Read more…
In the inexorable search for reduced weight, the various alloys of aluminium are most commonly used for high performance gasoline engines. Where peak firing loads are higher, for example as in the case of a modern direct injected diesel engine, this may need to be some form of S.G. (spheroidal graphite) iron. With its excellent flow properties in the molten state, sections can be cast much thinner than other cast irons and thus the disadvantage of a density nearer 7 gm/cm3 can, to a certain extent, be overcome. But when ultra low weight has to be the deciding factor then the only realistic choice is that of magnesium. Read more…
Love them or hate them, the two-stroke engine is in many ways far superior to its 4-stroke rival.
Specific power, specific weight, manoeuvrability, cost of manufacture, ease of maintenance, durability, NOx emissions and even fuel consumption in the case of smaller engines, can be far superior to its less controversial 4-stroke brother, but why then don’t we see more of these engines in competition?
With one strike for power and one to wear it out as Read more…
After having calculated bolt stiffness, or measured the load-deflection curve directly, the best way to calculate pre-load is to measure the extension of the bolt directly. This method is preferred for con rod bolts and all con rod and bolt suppliers generally recommend this method. The fasteners require design features to allow measurement with a special micrometer. This method is impossible for fasteners in blind holes. For large fasteners in blind holes the extension can be measured directly if there is sufficient access for other measuring equipment.
Ultrasonic methods are very accurate but don’t seem to Read more…
Last month we looked at the problem of how to contain excessive heat given off by hot exhausts. The problems this heat causes affect not only the engine, but also other systems, particularly electronics. In addition to wrapping or coating the exhausts, we looked at the concept of bagging or blanketing. Heat shields were mentioned and in Formula One at least these are commonplace, being lightweight and effective in shielding the engine from radiative heat transfer. The problem with wrapping or bagging of exhausts is the additional weight which would affect the reliability of the exhaust system Read more…
Today is the first of many strikes, or so we are told. The continuing dispute between management and unions in the Post Office has resulted in this, the first of a number of planned one-day stoppages across the UK on which the mere thought of reaching for an envelope and putting pen to paper is but the last thing on my mind. As engineers however, ‘addressing the envelope’ has an altogether different meaning. Other than a flat paper container with a sealable flap, to engineers an envelope is a containing structure or a boundary beyond which we stray only at our peril. Read more…
We should all be very familiar with the primary functions of a crankshaft, namely as part of the mechanism which converts reciprocating motion into rotary motion, and to transmit torque to the outside world, where it might drive a gearbox, a generator or other piece of equipment. What a great many crankshaft designs also do is to provide lubrication channels which allow the passage of oil to the big end bearings, and possibly thereafter to the small end of the connecting rod.
Many years ago, crankshafts were designed with external oil gallery circuits made of thin metal tubes fastened Read more…
Last month, we looked further into the use of titanium for con rods and this month we look briefly into the use of steel, which remains in many cases the material of choice for con rods. There are far more manufacturers of con rods who offer steel rods than any other material. Titanium is definitely on the increase, and possibly the time will come where steel becomes a ‘minority’ material choice. Some of the reason for steel remaining popular is the price of the raw material – it remains markedly cheaper than titanium. Another important reason is the familiarity of the suppliers with steel con rods. Many have Read more…
The use of polymer coatings in racing engines has been widespread for many years, but is to some extent being displaced by the newer generation of coatings such as titanium nitride, chromium nitride and DLC as examples. In a lot of circumstances the newer coatings are an improvement, but the coatings rely on the fact that there will be no significant deformation of the coated surface, otherwise the thin coating, which itself is brittle in comparison to the underlying substrate, can craze and flake off. Debris thus caused can, in some circumstances, go on to cause more serious failures elsewhere in the Read more…
In a good camshaft design the cam profile is but one half of the story. Lifting the valve off its seat and then opening fully before closing it again and dropping it gently back onto its seat requires a lot of careful mathematics and, executed well, should give the maximum valve area opening period for the minimum of forces involved. But just as much as efficient inlet and exhaust cam profiles are critical to any high performance engine, the timing of their opening and closing in relation to each other and in particular to that of the piston motion, can never be overstated. Read more…
