Not only is rallying an exciting sport to take part in and to watch, it places unusual demands on many of the components that make up the car and engine. Turbocharged engines in particular, with their anti-lag systems to aid transient response, place a lot of stress on components. In this regard, exhaust systems stand out as having to cope with more than their fair share of additional stress and hardship. Read more…
Archive for August, 2011
Rally exhausts
Friday, August 12th, 2011Valve-stem texturing - snake oil or snake skin?
Thursday, August 11th, 2011
The matter of ensuring that valve-stem lubrication is sufficient has two main benefits. First, any friction between stem and guide creates energy that is necessarily subtracted from crankshaft output power and converted to heat. Minimising this is clearly a desirable aim. Second, if the lubrication is sufficient, we minimise the rate of wear of the valve guide and valve.
There are a number of surface treatments that aim to Read more…
Double-spring valve springs for success
Thursday, August 11th, 2011
John Force Racing (JFR) is one of the most successful Funny Car teams in the history of the NHRA Full Throttle Drag Racing Series. Understanding that multiple team cars on the track results in successfully shared technology, JFR this year is competing with three drivers - John Force, Robert Hight and Mike Neff. There would have been four, but daughter Ashley Force Hood is taking the year away from competition to give birth to her first child. Read more…
Le Mans transmission
Thursday, August 11th, 2011
Le Mans places abnormal demands on almost every component in a racecar, with the suspension and engine taking a relentless pounding on every lap of the 13.629 km circuit. Also subject to the same war of attrition is the gearbox and driveline. In the past, gearboxes were a regular source of problems for competitors, either thanks to simple fatigue failures of parts, or driver fatigue leading to missed gearshifts. In recent years, transmission problems have become far less commonplace; this has been thanks to a number of Read more…
Peening
Thursday, August 11th, 2011
In the pages of Race Engine Technology and in these short web articles, there have been numerous mentions of the significant benefits of having residual compressive stresses present at the surface of a component. To recap, incorporating a method (or methods) of introducing residual compressive stress at a component’s surface is, in general, likely to improve the endurance limit of a component loaded in bending or torsion. Given that there are very few components that are loaded in a purely axial sense, this rule of thumb can be usefully Read more…
A twist in the tale
Thursday, August 11th, 2011
For all its apparent simplicity, your typical piston ring is a complex device. Required to seal against combustion gases on the power stroke and yet minimise friction on the upstroke, under all conditions of speeds and loads, the task might seem possible if we include the additional demand that all this and more should be achieved with the minimum of weight.
It is perhaps little wonder therefore that under the Read more…
Pushrod stiffness
Thursday, August 11th, 2011
The pushrod, or overhead valve (OHV), engine has a lot to recommend it in terms of packaging, although it achieves this at the expense of much valvetrain stiffness compared to an overhead cam (OHC) mechanism. One of the least stiff members in the pushrod valvetrain is the pushrod itself. Owing mainly to space constraints, but also possibly to mass targets in a smaller regard, the pushrod is a long slender component whose stiffness can dominate the dynamic behaviour of the whole valvetrain system. Read more…
Funny Car piston life
Thursday, August 11th, 2011
Mike Neff handles two jobs in the Funny Car category of NHRA Full Throttle Drag Racing - he is both the chief tuner and driver of the John Force Racing (JFR) Ford Mustang that currently tops the Funny Car points ranking and is the first car to qualify for the Countdown to the Championship play-off of six races, which starts after the Mac Tools US Nationals.
Neff handles the dual role easily, as he performed tuning Read more…
Oil tanks
Thursday, August 11th, 2011
Where regulations allow, most racecars run a dry-sump oil system, with the engine lubricant scavenged from the crankcase and stored in an external tank. This allows for a higher degree of oil control, a reduction in the possibility of oil surge and starvation, better de-aeration of the oil and, where applicable, a reduction in installation height thanks to the elimination of the sump pan. Read more…
The Plasma Transferred Wire Arc process
Thursday, August 11th, 2011
With engine manufacturers increasingly moving towards lightweight engine architectures, keeping the length of the engine to a minimum and using lightweight materials - particularly aluminium - is an obvious start. However, the process of replacing parent-metal cylinder liners in one-piece cast aluminium blocks, later on in the life of the vehicle, is fraught with difficulties. Traditionally, in less challenged times (both financially and engineering), blocks would have been re-bored and fitted with a system of separate wet liners. But with interbore Read more…
