It is a rather strange but ironic fact of life that once a racing engine gets over a certain age then the biggest causes of failure are not likely to be those associated with excessive loads or the breakdown of lubrication, but simply that of corrosion. In the prime of its often very short racing life, an engine may be cosseted by professionals whose whole existence is centred on the well-being of that unit. It will be stripped, cleaned and examined on a regular basis and then re-assembled with the utmost care and then crated away into storage perfectly preserved until the time comes for it to be active again and give its best.

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As an engineer and a power unit engineer at that, many might say that I have little need of a dictionary. And in truth, since the vocabulary of engineering terms tends to be so exact and rarely found in all but the most comprehensive of lexicological texts, for very many years I have simply done without. But it was while thumbing the latest version of the OED (Oxford English Dictionary) - the concise version I hasten to add, and a present given to me only recently, when I came across the word ‘Siamese.’ Defined as ‘a native of Siam (now Thailand) or an old fashioned word for Thai, Read more…

A motorcycle engine, indeed any engine running at over 10,000 rpm, presents a particularly difficult challenge to the surface of its cylinder bore. The amount of heat flux and the limited time to dissipate it through the cylinder wall and into the coolant, will inevitably lead to high running temperatures and all of its associated problems. Although lightweight aluminium cylinders have been used to assist with the heat transfer, to minimise durability issues, thin steel liners have often been inserted against the inner wall to reduce the piston ring friction, give some level of acceptable durability and avoid engine seizure.

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The surface condition of the cylinder bore has occupied the minds of motorists, engineers and enthusiasts for many years. Often expressed in terms of oil consumption – miles per litre or miles per quart depending upon which side of the Atlantic you reside – provided consumption isn’t excessive, all is generally thought to be fine. In a racing engine however, where cost of ownership is, let’s face it, more or less irrelevant, the real issue here is one of friction.

In recent years and with vehicle emission standards Read more…

Although cast iron cylinder liners have always been a safe and reliable choice, the differential expansion rate between them and the aluminium pistons, as well as their shear weight, has always encouraged designers to look for better alternatives. When cylinder blocks were cast iron, engines were so heavy as to make any change in the cylinder liner material utterly futile but as demands for lighter engines made aluminium more attractive, the push towards some kind of aluminium cylinder liner was only to be expected. Read more…

It is a fact not appreciated by many, except the specialists, but the technology of the cylinder bore surface finish has changed significantly over the years. While oil consumption was perhaps the greatest driver in the past, the push to achieve even less and less exhaust emission at higher and higher mileages, has caused OE engine manufacturers to focus even greater resources into getting the surface finish of the cylinder bore exactly right. And while, to the OEM this means emissions approval, to the racing industry this technology brings less friction and wear and with it, improved performance. Read more…

Historically, the relatively soft grey cast iron cylinder liner with its inclusions of graphite, correctly prepared, has made an excellent material when running against much harder chromium plated rings. However, the differences in thermal expansion between the liner and that of the aluminium alloy piston make it necessary to introduce a greater than desirable radial clearance to prevent piston scuffing and eventual seizure.

As the specific performance increases along with larger diameter pistons, the pressure to move to bore materials

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You can’t talk about cylinder liners for very long without referring to the terms of either ‘wet’ or ‘dry.’ Although fairly self-explanatory, these refer to liners, which are either in direct contact with the engine coolant or those which are not. And at one time, and more years ago than I care to remember, these terms may also have referred to a certain type of Tory politician. In those recessionary times (yes, we had them back then as well!) monetary policy was the political mantra and you either believed in it or not. Likewise with cylinder liners, you are either a firm believer in wet liners or you are not.

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The humble cylinder bore seems to get very little press these days. Arguably the most critical surface in any combustion engine, the inside surface of any cylinder liner is exposed to the full flame temperature and the high pressures of combustion and yet still has to form an almost gas tight seal against the piston ring. And all this we ask with minimum wall thickness and hence minimum weight. While the more modern high performance engine designs might have any form of nickel ceramic coating over an aluminium alloy base material for light weight, low friction and optimal lubrication, it shouldn’t come as much of a surprise to most that the vast majority of cylinder

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Kalitta Racing has been around for 50 years in NHRA Top Fuel racing. As with every team in this category it uses a Hemi-patterned, 500 cid, 90-degree V8 engine with forged aluminium block (solid; with no water passages). The sleeves (cylinder liners) are made of centrifugal cast ductile iron of special formulation (ASTM 536-84) and are ‘slip fit’ into the aluminium block with 100 percent cylindrical contact.

Each sleeve is held at the top by a flange and has a stainless steel wire ring in a groove on the top of the flange that, in turn, penetrates a solid cooper gasket for block/head sealing. Read more…