In a previous RET Monitor articles, we have looked at a couple of valve materials, namely titanium and titanium aluminide. The chief advantage of these materials is their low density which has obvious appeal when trying to keep control of valves at increasing engine speeds. Titanium aluminide, besides being possessed of even lower density than titanium has the additional advantage of increased stiffness, making it an excellent choice for poppet valves. Read more…

There are a number of coating companies offering thermal barrier coatings, and some claim that internal combustion engine valves are an ideal candidate for these types of coatings. There are many whose advertisements target the racing community in particular.

The coatings that these companies offer are generally quite thin ceramic coatings which offer very low thermal conductivity compared to the valve material. We should at this point note that a titanium valve has very much lower thermal conductivity than a steel valve. Read more…

The tip of the racing poppet valve is seldom considered, despite having to withstand relatively high contact stresses. Whilst we can say that the contact stresses concerned are generally low compared to other valve train applications, the relative movement between the valve tip and the adjacent component can be low, especially in the case of overhead cam engines where a lash cap or, more rarely, a bucket follower applies the load to the valve.

Even in the case of those engines where rockers are used, the sliding velocity of the adjacent parts, relative Read more…

In recent articles, we have assessed some of the materials employed in the manufacture of racing valves. This month we will take a break from this recent theme, and take a brief look at some of the surface treatments used on racing valves, perhaps returning in the future to look more deeply at some of them. Read more…

Thus far we have examined the application of titanium in the production of racing valves, and seen how the properties of this material may be tailored to the application by either specific heat treatments, or by combining materials with different mechanical properties within the same valve by the use of friction welding. We reflected on the fact that titanium, compared to steel and most of the other materials that we would traditionally use for valve manufacture, offers a lower mass valve when properly optimised. Read more…

Last month, we looked at the application of hollow valves, and noted, as had Anne Proffit’s recent article, that titanium is a popular choice for these components. Many engineers who specify hollow valves do so for reasons of mass reduction and improved valve control; hence titanium is a natural choice in this respect.

Titanium has very low density compared to the more traditional poppet-valve materials and so is the kind of material that we look to when trying to minimise mass as part of a valvetrain optimisation exercise. Read more…

Following on from Anne Proffit’s recent article on the application of hollow valves in drag-racing, we look at some of the more general benefits of hollow valves and their use in racing. These valves are used in all sorts of racing engines (and have also been used in production engines in the past). Particularly in Formula One they are used extensively.

Whilst hollow valves would offer a weight saving over their solid equivalent (given the same stem diameter), they would be less stiff and so would almost certainly Read more…

Following on from my recent article on valve-head profiles, we will look a little further into the valve-head profile, and how this is applied to the modern Formula One engine. As speeds rose above 20,000 rpm in Formula One, this was an area of intense development, but the pressure has been slightly removed owing to the decrease in speeds as imposed by the yearly rev-cut regulation. Into the third year after the 20,000 rpm race engines of 2006, we now have a mandated 18,000 rpm engine speed limit.

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The use of hollow stem titanium intake valves is slowly beginning its reach into the drag racing community, as a few Top Fuel teams are taking on the use of these weight saving and power enhancing parts that are used in many other series. Sometimes it just takes the drag racers a bit longer to embrace newer technology, notes Tom Abbett, team manager and cylinder head specialist at Mike Ashley Racing.

According Abbett, this type of intake valve significantly lightens the overall valvetrain and is easier on the

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There is a conventional wisdom that has developed around intake valve configuration: cylinder heads equipped with ports inclined at narrow valve angle to the valve stem should have conical, or ‘tuliped’ back faces, and ports that have significant bend at the intake valve should have shallow back angles i.e. the classic ‘nail head’ shape present in so many large pushrod engines. While this is true much of the time, there are exceptions, and frequently the desired point of improvement in the power curve can be as much a factor in the decision as the port configuration. Read more…