Archive for the ‘heads-blocks’ Category

Compacted Graphite Iron, or….not?

Tuesday, August 17th, 2010

heads-blocksIn 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…

Fractured accuracy

Friday, July 2nd, 2010

heads-blocksAs 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…

Elixir of life

Thursday, May 13th, 2010

heads-blocksIt 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…

Valve seat resurfacing

Tuesday, March 30th, 2010

heads-blocksEver 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…

A Most Unusual Engine

Tuesday, February 16th, 2010

heads-blocksAn 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…

The Cooling System

Thursday, January 21st, 2010

heads-blocksA 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…

Casting back

Saturday, December 19th, 2009

heads-blocksThe 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…

Magnesium in the cylinder block

Sunday, November 15th, 2009

heads-blocksIn 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…

MATERIAL SELECTION

Monday, October 12th, 2009

heads-blocksIf you’ve been in the automotive industry for any length of time you will by now have the words “higher performance, less weight at a cheaper price” more or less burned into the inner soul of your psyche. Since weight is the ultimate destroyer of any performance improvement, it nevertheless rankled if ever we were to reduce the weight of the power unit by some paltry amount someone always managed to find room for yet one more electric motor in the seat! Be that as it may and despite the extra level of driver (or passenger) comfort afforded, the inexorable search for lighter, more powerful engines goes on. Read more…

Bearing Up

Sunday, September 13th, 2009

heads-blocksIsn’t it strange how solving one issue in racing can sometimes lead to solving a different problem in production engines many years later. The evolution of the main bearing cap springs to mind.

It was while examining a cylinder block prior to rebuilding a classic engine that made me reflect on how far, in terms of technology modern road vehicle engines have come. The crankcase in question was a five bearing four cylinder unit of 1970s origin and having a relatively undersquare bore/stroke ratio would rev regularly up to 9000 rpm. Read more…