Engine Productivity Basics Continued: Cylinders

This week’s tip will focus on another component critical to proper engine performance and productivity – the cylinder. While not terribly fancy, this component allows the development of engine power.

Follow these tips to properly lubricate this component and help enhance the performance of your engine.

Cylinder basics

The cylinder is a central component for the internal combustion engine, or for that matter a reciprocating pump. It allows for the development of pressure as the piston rise up to compress the air / fuel mixture. In an engine or pump, cylinders may be aligned in the following ways: inline, v-position, opposing, or radially. The most common is the v-arrangement, where cylinders are contained in two banks.

The cylinder is typically cast from aluminum or iron. It may be cast into the block or introduced as a sleeved insert. Cylinders are also classified as either wet or dry. “Wet” means the cylinder comes into direct contact with coolant, and “dry” means the exact opposite.

The cylinder’s impact on engine displacement

A common misconception is that engine displacement is determined by piston size. While the correct piston diameter allows for compression, the displacement is in fact determined by the cylinder volume, piston bore and stroke, as well as the number of cylinders. See the following calculation:

  

So in an eight cylinder, five liter engine, each cylinder would have a displacement of 0.625 liters.

Cylinder lubrication fundamentals

As most operators know, compression is provided by the motion of the piston and piston rings, all of which takes place inside a cylinder.

But, did you know that if lubricated properly, a piston ring never touches the cylinder surface? The piston rings ride on a thin layer of oil which provides a seal, enabling compression.

Proper cylinder lubrication is provided by the oil contained in the crankcase, which is either splashed up or delivered by pressure to the cylinder.

The key feature of the engine oil used to lubricate the cylinders are oxidation resistance and anti-wear capabilities. The latter is important as it must help prevent metal-to-metal contact between the rings and cylinder, particularly in the piston turn-around zone.

Lubrication of the cylinder is facilitated by “hone” marks. These are the results of a machining process performed on cylinders to remove asperities from the surface. Honing creates cross-hatch marks on the surface of the cylinder. If you look closely at the photograph below, you can see these marks.

These marks serve two equally important purposes:

  • The presence of hone marks when inspecting a cylinder suggest that the bore is intact and negligible wear has occurred.
  • The hone marks by their design retain oil and therefore they facilitate the piston ring / cylinder lubrication.

There is debate as to which is more important, but given the keys are wear versus proper lubrication, they are both vital considerations.

I hope this week’s tip was helpful, and don’t hesitate to leave a question or comment in the section below.

Anonymous
  • Jorge - Yes, it would be within limits for that particular grade of oil.

  • Una duda..... después de una rectificación la viscosidad del aceite tendría que ser mayo o seria la misma que originalmente se manejaba? Gracias!!

  • Nikolay:  Information on different pistons designs is interesting but really beyond the scope of the blog.  

    1.  Piston design:  f you do some research you will see that piston design has changed but that form and function is essentionally the same.  Pistons have gotten smaller and lighter, have better heat transfer materials and some materials used can withstand more heat and pressure.  Most of these changes are designed to help with increased HP demand and fuel efficiency.  Skirts have been shortened to allow for a smaller block which again saves weight.

    2.  Block by engine type:  They are essentially the same regardless if the engine is diesel, gasoline, in-line or V-shaped.  The blocks of gasoline and diesels typically differ in that the diesel block is made of stronger materials, iron versus aluminum.  This is due to high compression and greater torque developed in the engine.  The block differences between in line and V are in design only.  The materials can be the same.  In an inline engine, the pistons are not opposed and exhaust and intake ports are all on one side but not necessarily the same side.  V engines have exhaust ports on both sides and the design allows for a block that is smaller then an Inline with the same number of cylinders.  Smaller means lighter and better fuel economy.

    I hope this helps.

  • Интересует

    1. По конструкции поршней:Поршни с укороченной юбкой  и поршни с уменьшенной высотой между днищем и кольцами.

    2.Двигатели:По  типу топлива: бензиновые,дизельные,газовые.По конструкции:рядные,V -образные.

  • Gracias por tu aportación Rick, me llama la atención lo que mencionas sobre las marcas de rectificado y como estas benefician a la lubricación, tiene sentido lo que mencionas

    Sin embargo dentro de la industria automotriz es mas usual que los diseñadores de motor soliciten el acabado espejo en sus componentes, no se si esto afecte o beneficie a la lubricación de motores

    En otros casos particularmente en piezas templadas, algunos fabricantes solicitan que al realizar el acabado espejo se destapen algunos poros de diámetro aceptable que facilitan al lubricación, son características de micro acabado que las piden con un cierto numero de poros dentro de un área de medición

  • Nikolay - you mention

    1.   You want information on different types of pistons and cylinders - What additional types are you refering too?

    2.  You mention different engine designs.  What engine designs would you like explained here?

  • Не хватает данных по моторесурсу цилиндров и поршней в разных типах и конструкциях  двигателей.

  • 1.  Does the kind of oil effect in the wear rings ?  Yes.  The oil should be of appropriate viscosity and contain anti-wear additives and an effective detergent dispersant package.  

    2.  If Ichange the oil for anther kind is that effect in rings or not?  If the change is from a leading engine oil to another, the rings probably will not be effected.  If you change from an oil low in detergent to one high in detergent, the deposits on the rings could come free.  

  • DID the kind of oil effect in the wear rings ?

    if i change the oil for anther kind is that effect in rings or not ?

  • Gracias por su respuesta,para saber en caso de que se nos presenté cuando vea estos síntomas y tomar acción inmediatamente,saludos Rick.

  • Loss of power and increased oil consumption.

  • ¿Cuales serian los principales síntomas de averías en los cilindros del motor?