In my previous Heads-Blocks article I described the advantage of Compacted Graphite Iron (CGI) on one of the most severe cylinder head failure modes, Thermo Mechanical Fatigue (TMF). The main area of interest then concerned differences in material properties. Of course, material is not the only contributor to TMF robustness of cylinder head design, so in this article I will give an insight into another parameter influencing TMF, coolant jacket design. Read more…

It’s widely known that Compacted Graphite Iron (CGI) has a number of material properties which in certain applications make it the material of choice for cylinder blocks. So does this also apply to race engine cylinder heads and, if so, why?

First let’s look at some of the key criteria of a cylinder head. It has a number of functions, such as keeping gas and coolant inside, and providing the structure for assembling or bolting on other components - valve seats and guides, for example, but also camshafts. To do so, Read more…

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…

As can be seen from earlier articles in RET-Monitor on race engine block material, a trend can be seen towards Compacted Graphite Iron as a crankcase material. It has been used occasionally in the past on highly loaded motorsport applications but it now seems to have become more widespread.

The reasons for this are the higher mechanical strength of the material in relation to increasing combustion loads, and a broader availability of CGI Read more…

It is often said that water is the elixir of life. But when used as a coolant in a high-performance racing engine it can be the kiss of death instead. Let me explain.

Ever since the invention of the ‘heat’ engine, limits to the properties of the metals used mean they have necessitated some kind of cooling. And since water is all around us, it makes sense to use this is a transport fluid to remove heat from the cylinder head and disperse it into the atmosphere. Read more…

Ever since the dawn of mass manufacturing, engineers have been preoccupied with shape and position but it is only in comparatively recent times that this has been formalised into a geometrical standard. The language of geometric dimensioning and tolerancing, GD&T to you and me, consisting of rules, symbols and conventions, was designed to ensure parts could be made anywhere in the world and put together with the highest confidence to produce a fully functional product or assembly. Specifying characteristics like form, orientation and Read more…

An engineer should not only have solid grounding in the fundamentals of his discipline but an interest in history too. A thorough understanding of the principles involved in product design is, I would have thought, an absolute necessity but an appreciation of all that has gone before is as equally valuable. So when other people are perhaps relaxing or enjoying the fruits of their labour I often prefer to saunter around some of the smaller transport museums in this land. On one occasion hidden behind a glass case I came Read more…

A major consideration of any engine designer right from the outset is that of the cooling system. Even in the most efficient of gasoline race engines, only 35% of the fuel energy available is converted into mechanical power. The rest, something like 850kW from an engine delivering 450kW, is converted into heat which will need to be dissipated into the surrounding atmosphere. Putting it into perspective that’s something like 280+, 3kW electric fires worth of heat, approximately half of which will go out through the exhaust system with the remainder - around 400kW rejected Read more…

The trouble with advancing years, or so I was always told, was that you can always remember how it used to be. In the dim and distant past, it seemed to be much more fun (even though it probably wasn’t) and if the job couldn’t be precise then we always made it as accurate as we could somehow adapting the product to the limitations of the manufacturing process.

A typical case of this, I was reminded recently, was in the casting of cylinder heads and crankcases. In those days and I am only talking about the 1960s here 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…