There have been a number of articles about fasteners that have mentioned friction, and as we have discussed, this has an important effect on the relationship between tightening torque and tension. Although torque-based tensioning of fasteners is not ideal, having a large number of unpredictable variables, we often don’t have much choice other than to use this method.
The torque-tension relationship relies on a number of Read more…
MotoGP represents a real technical challenge for those who have the resources to design a bespoke race engine. The rules are refreshingly simple and short. There is very little to restrict irresponsible levels of spending, apart from common sense. The engine may have any number of cylinders in any configuration. Where Formula One dictates the number of cylinders and layout of the engine, MotoGP allows any design. Although we don’t currently have anyone using more than four cylinders, we do have a mixture of inline four-cylinder engines and V4s. Read more…
With a number of new race formulae moving over to pressure-charged engines, the second decade of the 21st century looks set to become the Second Coming of the turbocharger. The First Coming, of course - if my memory serves me correctly, back in the late 1970s/early ’80s - was all about boost levels and ultimate power. This time around, with virtually all vehicle OEMs looking at downsizing and turbocharging their street offerings, it’s about efficiency. And, as such it, will be more important than ever to get the engine Read more…
Although the water or hydraulic brake is probably the most cost effective form of dynamometer, by far the most familiar - at least for those in a professional engine development environment - will be the eddy-current brake. It’s a bit of a hybrid in a way, for although it’s classed as an electrical machine, it still requires a method of dissipating the engine shaft energy absorbed in the form of heat. In low power ratings this can be cooling air, which greatly simplifies the installation, but when much larger power ratings are required the only Read more…
In the recent Alternative Energy Focus article in Race Engine Technology magazine (issue 53, March/April 2011), the subject of KERS and its different strategies were discussed. The car manufacturers - thus far at least - have opted to use a purely electrical system. A large combined motor/generator converts kinetic energy recovered under braking into chemical energy stored in a battery, and then the stored energy is re-used at will once the vehicle is no longer traction limited. The technology is well understood and the car manufacturers Read more…
It is common to see composite materials in a range of applications in motorsport. Typically glass- and carbon fibre composites reinforced within a polyester or epoxy matrix not only lend themselves to the manufacture of complex shapes but also allow engineers to incorporate both isotropic and anisotropic mechanical properties into a single structure. As with all composite materials, the constituents’ properties and the positioning of both the reinforcement and matrix material will determine the overall composite material’s properties.
The contribution of the piston assembly to overall engine frictional losses is well documented and has been the subject of a lot of research over a number of decades.
In SAE paper 911230, for example, the authors Tsuchida and Tsuzuku study the effects of various design features on piston friction losses for high-speed engines (up to 16,000 rpm). At the time - the late 1980s and early ’90s - the Japanese were selling production motorcycles with engine speeds higher than even Formula One engines Read more…
High lifts or long durations are common features in high-performance camshafts, and when optimised can produce high engine torques over a useful but often limited range of engine speeds. The introduction of variable valve timing can widen this range of useful speeds, but at part load against a partially closed throttle, large valve lifts introduce pumping inefficiencies that are increasingly unacceptable in performance roadcar engines. Over the past decade, therefore, a multitude of variable valve lift concepts for spark-ignition engines have evolved. The simplest of these is the Read more…
Making a comeback from earlier times, the ball-race bearing system may be a preferred solution in some turbocharger applications, but for reasons of cost the more usual approach for the vast majority of units is still the fully floating design. Consisting essentially of two bushes, one at either end of the bearing housing through which the shaft passes, unusually these bushes themselves are allowed to rotate in their housing, creating in effect a ‘bearing within a bearing’. Read more…
The applications of copper alloys in engines are generally those where we might expect to see relative movement or where a combination of strength, wear resistance and thermal conductivity is required. A favourite type for many of these applications are the copper-beryllium alloys.
Beryllium is a very lightweight element, and has some attractive mechanical and physical properties. However, there are health considerations regarding its use. Read more…
