Low-density, high-strength alloys
In a previous article on aluminium-beryllium, we looked at how its combination of low density, stiffness and thermal conductivity makes it ideal for pistons. As I explained though, the material - for Formula One at least - is now prohibited, and outside Formula One, there is perhaps little appetite for using it.
Besides pistons, I mentioned a number of other applications where aluminium-beryllium might be considered, including static applications. In this article we will look briefly at some of the other materials used in reciprocating applications where aluminium-beryllium is now banned.
Read more…
RET Focus: Advanced Metals, view the latest magazine article here.
Why and when to develop an equivalent for leaded bearing materials?
In the July 2010 issue of RET-Monitor, keyword: bearings, I wrote about lead-free bearings and possible engineering concerns surrounding their introduction. Extending the search for the reasons behind why the substitute for leaded bearing materials is not yet embraced by the race engineers led to a short interview with a leading supplier of competition bearing shells.
In addition to possible sensitivity issues concerning roundness (shape and steps in the circumference of the bearing bore) and the lower conformability and embedability of the unleaded, harder materials, the temperature inside the bearing is considered to be of major importance in the selection of the bearing material.
Read more…
RET Focus: Bearings, view the latest magazine article here.
Camshaft surface finish
The complex interaction of components that represents the valvetrain operates in some of the most difficult tribological circumstances. With rapid changes in instantaneous direction between adjacent parts, and high contact stresses, the challenge of maximising the output of the engine while maintaining an acceptable level of reliability has never been more onerous.
While it is true that the vast majority of camshaft wear takes place during cold start and warm-up, when the temperature of the oil is less than 60 C, the durability and performance of the valvetrain can still be a major consideration when the engine is operating at its normal working temperature. At the most basic level it’s all about friction and its inevitable consequence - wear. Read more…
RET Focus: Camshafts, view the latest magazine article here.
Thermal dispersion coatings
In the recent coatings Focus article in Race Engine Technology (Issue 47, June/July 2010), there was brief mention of thermal dispersion coatings. The aim of these coatings is to eliminate surface ‘hot spots’ on components and thereby equalise the temperature. Their most common use is on cooling system components, although one supplier we spoke to said one of his customers found success using the coating on aluminium connecting rods, making them less prone to failure.
In terms of the eliminating surface hot spots, there are obvious advantages with being able to do this. There are many materials used in or around a race engine that experience a significant drop in mechanical and fatigue properties with increasing temperature. If we can achieve a better temperature distribution over the surface, we could avoid there being a premature failure at the hot spot. Read more…
RET Focus: Coatings, view the latest magazine article here.
Metal-matrix composite rods
In my previous article on the subject of con rods I asked, “Can we manage without big-end bearings?” and went on to look at the various attempts to do this and the possible future options. The article briefly mentioned the benefits of not having a bearing, and observed that there is one currently successful application of bearing-free technology being raced.
In the application concerned - four-stroke, single-cylinder race engines with ‘assembled’ cranks, where the crankshaft isn’t a single piece but is assembled with the con rod in place - there is an advantage in terms of design simplicity: the con rod can be a single piece rather than an assembly split at the big end. This means that there is neither a requirement for bolts to secure a cap, nor dowels or pins to ensure correct rod-to-cap alignment. Read more…
RET Focus: Conrods, view the latest magazine article here.
Camshaft drive gears
While the main purpose of a crank is obvious, it has many other demands placed upon it. Rotating constantly as it does, it is ideal for taking drives to other assemblies such as pumps. While it is possible to drive pumps electrically - and there are some advantages to doing this - it is banned in some forms of motorsport, and the vast majority of series-production engines drive their pumps mechanically.
With very few exceptions, four-stroke engines use camshafts to open poppet valves, and the cams need to be driven at a fixed speed ratio to the crankshaft, and timed to the motion of the piston very precisely. While it would perhaps be convenient to do so, nobody drives the cams electrically, and so a mechanical connection between the crankshaft and the camshaft(s) is necessary. Read more…
RET Focus: Crankshafts, view the latest magazine article here.
The control freak
I’m sure we’ve all been accused of it at some time - the compulsive desire to have things just the way we want them, with little or no compromise. Perfection is the goal, anything else is a poor second best and, except in the case of pure genius perhaps, it is often considered a major flaw in one’s character. But in the world of engine dynamometers, control is everything.
Many of you will no doubt be familiar with the large and unmistakable throttle lever alongside the console of an older engine test bed. Linked directly to the engine throttle via an equally unambiguous control cable or metal rod, throttle control was left entirely to the tester, and should anything become amiss or the engine detonate for so much as a split-second, the throttle would be wrenched away from fully open or rammed shut as an instinctive reaction. Read more…
RET Focus: Dynamometers, view the latest magazine article here.
X-by-wire
One of the biggest changes to the engine ECU in recent years has been the rise of the drive-by-wire system. Generically known as ‘x-by-wire’ or sometimes (incorrectly) as ‘fly-by-wire’, such systems were introduced by vehicle OEMs in response to more punitive emissions legislation in recent years.
Consisting of a throttle pedal device requesting a torque demand from the engine, the engine ECU calculates the ignition and fuelling necessary and requests the appropriate amount of air from the engine throttle. With no physical cable connecting the throttle pedal to the unit on the engine, communication is achieved solely via electronics and digital signals. Systems similar to these were first used without mechanical back-up in the F-16 jet fighter in 1974 and then the Airbus A320 commercial airliner 14 years later. Read more…
RET Focus: ECU-EMS, view the latest magazine article here.
Superstock and Superbike
I recently spoke to Emmanuele Nicali of Lesto Racing at the Monza World Superbike races about the company’s motorcycle race products. Lesto supplies both road and race motorcycle exhausts to a number of teams involved in various Italian national championships, including CIV (Italian Superbike championship) and the Superstock 600 and 1000cc series. It also plans to have its exhaust systems on race machines at the Isle of Man TT races in 2011. Fig. 1 shows a race system fitted to a race Suzuki.
The company uses racing as a way to improve its products through the increased speed of development, and the teams it supplies are an active part of this process. It names CDS Racing Team and SGM Tecnic as teams with a lot of experience that, according to Nicali. “help us test our product on track and boost performance under racing pressure”.
Read more…
RET Focus: Exhausts, view the latest magazine article here.
Composite Materials
The use of composite materials in racecars is not new; nor does it represent a particular novelty for race engines. The strength, stiffness and low density make them ideal for many components, both structural and decorative.
It is now pretty rare to find a race engine airbox, certainly on ‘formula’ cars, made from anything other than carbon-fibre reinforced polymer (CFRP) composites. It has also been used to good effect for plenums on turbocharged engines, on structural covers for race engines and in parts used specifically to increase the stiffness of the engine in order to provide a performance benefit to the vehicle as a whole. It is widely used for electrical boxes and cosmetic covers too. Read more…
RET Focus: Fasteners, view the latest magazine article here.
Fuel economy
To many, the words ‘fuel’ and ‘economy’ have no real place in the motorsports world. After all, and as everyone knows, to save fuel the driver has to be delicate on the throttle, avoid braking and keep in as high a gear as he (or she) can. And with these actions seemingly totally at odds with the concept of travelling quickly, I might find it hard to do anything other than agree.
Nevertheless, there are times when race organisers wish to restrict the amount of fuel carried on board and therefore stipulate a maximum tank capacity to which all competitors must comply. In such cases, in order to finish the race and assuming refuelling is not allowed (or even desirable), it will be necessary to eke out the fuel supply in some way or another. Read more…
RET Focus: Fuel, view the latest magazine article here.
Compacted Graphite Iron, or….not?
In the July 2010 issue of RET-Monitor, keyword: heads-blocks, I gave some insight into fracture splitting of the main bearing cap. The advantages of a fractured split line were discussed, including the design freedom that can be achieved using fracture splitting.
What I did not mention though - and this is where this article connects to the previous one - is the fact that fracture splitting cannot be done with every type of cast iron. Based on the process-specific requirements, fracture splitting is possible when using Compacted Graphite Iron (CGI) material. So would there be more to gain using this material, and what are the limitations? Read more…
RET Focus: Heads Blocks, view the latest magazine article here.
A reminder of the first Le Mans KERS effort
There has been much time, effort and money expended in bringing kinetic energy recovery systems (KERS) to Formula One. The much-heralded introduction saw many of the teams developing a system at great expense and not choosing to race it, or those racing with KERS not really seeing a huge benefit.
At the end of the 2009 race season, the media seemed to be of the opinion that the team that had achieved most from KERS, having used the most successful system, was McLaren. Its KERS system was developed in conjunction with Mercedes and Zytek. Read more…
RET Focus: KERS, view the latest magazine article here.
The steel liner
When it comes to liner technology, the temptation is always to think in terms of cast iron - whether it be grey cast iron or one of the more recent ductile - or aluminium. Each takes its lead from the cylinder block supporting them and therefore, for reasons of thermal expansion, sound engineering sense seems to suggest that we stick to the same generic material.
There are exceptions though. Hypereutectic aluminium alloys (aluminium alloys containing more than 12 % silicon) for instance can be used successfully in cast-iron blocks where the lower rate of expansion is comparable, and of course cast-iron liners can be used successfully in aluminium blocks. But there is one material that is regularly used in many engines, particularly diesels, and which is only seldom used in competition engines - steel. Read more…
RET Focus: Liners/Sleeves, view the latest magazine article here.
The Roots-type scavenge pump
I suppose it’s the mechanical engineer in me but ever since I can remember I have always been fascinated by complex curves. It may have been the Spirograph I received as a child, rolling one circle around another to produced a series of intriguing spirals. Or it could have been the Lissajous figures describing complex harmonic motion later on at university. Either way, the complex geometries produced in such a simple way left a major impression.
The geometry of the gerotor oil pump is developed from such a simple approach. Rolling one circle around another, but in the special case when the radius of the smaller circle is exactly half that of the larger, a shape similar to that used in a Roots-type supercharger is produced. Read more…
RET Focus: Oil Pumps, view the latest magazine article here.
Historic piston use in the midget engine
Dan Esslinger, President of Esslinger Engineering has been building Midget engines since 1990 - “So I guess we’re 20-ish years into this thing,” he says. In that time, Esslinger Engineering has gone through perhaps 30 iterations of pistons, “That’s been due to bore size change, different strokes, different rod lengths, valve locations, things of that ilk,” he says. “If you change one, it all changes.
“Typically we use JE three-ring pistons because they are local (less than an hour away from Esslinger’s shop) and they do an outstanding job. They work with us and turn stuff around in a hurry. We’ve found they make fewer mistakes than we do! Sometimes we ask for things we shouldn’t and they (the pistons) get stuck in engineering that way. JE generally gives us what we ask,” Esslinger says. Read more…
RET Focus: Pistons, view the latest magazine article here.
How does it fit at the end(s)?
In the pushrod section of RET-Monitor the reader has been given an insight into the different aspects of pushrod design. Much information has been shared on the specifics of the pushrod concerning its shape, material and contact area of cup and/or bowl.
The specifics of the connection between the either hollow or solid centre part of the pushrod has been briefly touched on. In this article the different concepts of connecting the pushrod ends to the centre part are explored further. Read more…
RET Focus: Pushrods, view the latest magazine article here.
The ductile iron ring
Lest you think Fig. 1 here is the remnant of some form of horrific engine blow-up, let me explain that what you are looking at is a ductile iron piston ring. Twisted and bent to all manner of shapes the resulting contortion demonstrates vividly how flexible the material can be.
Ductile iron comes from a class of materials referred to as SG (spheroidal graphite) irons. Similar in composition to the grey cast-irons used in older type piston ring technology, the carbon flakes in grey cast-iron have been converted into a round, nodular form, inhibiting the formation of micro-cracks and making the resultant iron considerably more ductile and very much less brittle. Read more…
RET Focus: Rings, view the latest magazine article here.
The water pump seal
Time was when the application of the white of a single egg - be that free range or battery, it didn’t seem to matter which - was enough to cure that annoying little water leak. Dropped into the top of the radiator, the action of the engine being progressively warmed was sufficient to denature the protein in the albumin and form a thick white mass, sealing the leak or at least sealing it enough to get you home. But with modern critically cooled engines, narrow cooling passageways using minimal amounts of transfer fluid, such practices are best consigned to the memories of old men and heroic tales from the past. Read more…
RET Focus: Seals / Gaskets, view the latest magazine article here.
The WPC process
For those of you with a high boredom threshold, a constantly recurring theme in my articles for RET-Monitor and Race Engine Technology is to stress the importance of compressive residual stresses at the surface of components which are cyclically stressed. The compressive stress is extremely effective in improving the fatigue strength of engine components, and there are a number of ways of achieving this; some of these have been discussed before in RET-Monitor. Read more…
RET Focus: Surface Treatments, view the latest magazine article here.
Formula One CVT (Part 2)
In the previous article, we looked at the prototype Formula One constantly variable transmission (CVT) system that Williams developed in conjunction with Van Doorn in the early 1990s, and spoke to engineer Arnaud Boulanger who was involved with the project.
Anyone who follows Formula One closely will remember the dominant position that Williams had at that time. The CVT’s development happened during a golden era for Williams; having the best car, they attracted the best drivers and for years were considered ‘kingmakers’ owing to the fact that, more often than not, the world champions drove a Williams. Read more…
RET Focus: Transmission, view the latest magazine article here.
Going lighter and stronger
Esslinger Engineering of South El Monte, California, is primarily in the business of building midget engines based on Ford internals. The company has been in this line of work since 1990.
Because its engines are not based on pushrod designs, Dan Esslinger, president, says there are not very many valve-spring issues. “It’s just the design of the engine and the design of the camshaft,” he says. “Even though we turn a lot of rpms (in the neighborhood of 10,000), we are not cycling the kind of weight that a pushrod engine would, so the valve springs haven’t been nearly the issue they have been for some other builders.” Read more…
RET Focus: Valve Springs, view the latest magazine article here.
Austenitic steels
So far in Race Engine Technology’s coverage on valves, there have been a number of articles on valve materials for the more extreme applications, specifically pieces on Inconel valves and Nimonic materials used for turbocharged endurance applications. There have also been articles on the lightweight valves, made from low-density materials such as titanium and titanium aluminide.
Valves made from these materials are expensive for various reasons, some to do with the price of the raw material, some due to the immaturity of the technology and some due to the extra processing time required to produce the valves. While it is always interesting to take note of the latest materials technology, there are many people in our sport who can afford neither the cost nor the risk of running these materials, and would derive little real benefit from doing so anyway. Read more…
RET Focus: Valves, view the latest magazine article here.
