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Piston Business Card Holders: The most common form of advertising is a business card. When your looking for a customer to put faith in the fact you can do the best job the every detail in your business should stand out including your business card holders. It has become absurd at this point the regularity the Pistons pick in that slot, and its directly responsible for the terrible decade+ all of us have sat thru. Last lottery, #7 was the highest pick since Monroe at #7(2010!!!), and before that Darko at #2.(2003!) Think about how long this team has sucked butt, and that is the highest pick. Definition: It can be defined as a machine that is used to displace liquids or compressed gases from one point to another. It is a positive displacement pump where a high-pressure seal reciprocates with the piston. These pumps are used where there is a requirement of high consistent pressure, like in water irrigation systems. All pistons can be upgraded to double pin oilers with banana groove slots on each pin boss. This provides two direct lubrication sources to each pin boss, and the banana groove slots are there to help distribute the oil around the boss to ensure broader lubrication coverage. It has become absurd at this point the regularity the Pistons pick in that slot, and its directly responsible for the terrible decade+ all of us have sat thru. Last lottery, #7 was the highest pick since Monroe at #7(2010!!!), and before that Darko at #2.(2003!).

Piston parts, unlike designs and material, do not vary across different pistons. They remain the same with differences only in their sizes.

This article explores the automotive piston assembly components, detailing the function of each.

To make identifying each part easy, we added images in the descriptions.

Piston components extend all the way from the part bordering the combustion chamber to the end that connects to the crankshaft. Collectively, these parts make the piston assembly.

These are the components we will focus on. Before proceeding, here is a diagram showing all piston parts.

Now, on to a detailed description of each component.

1. Piston Ring

Piston Ring Definition

Piston ringsare pieces of split rings that mount on a recessed area of the piston. Thereare usually 3 piston rings in a typical car engine. The number varies, and a pistoncan even have one ring. The areas or surfaces between these rings arecalled piston ring lands. The ring mounting grooves are designed to maintain the piston ring position, andyou may hear something like tapered construction.

The split design of the piston ring has several benefits. It allows for spring action, which helps the rings to maintain the correct piston ring gap. The split also makes piston ring installation easy. To ensure spring constant under heat, load, pressures, and other conditions, manufacturers prefer cast iron or pieces of steel for piston rings material.

Piston Ring Function

The primary function of piston rings is to seal off the combustionchamber and regulate lubricating oil usage. The rings also serve to conductheat away to the cylinderbore. As mentionedbefore, most vehicle engine pistons feature three rings; two upper compressionrings and a lower oil ring. For clarity, the different rings are explainedbelow.

  • Compressionring– this is the top side ring and nearest the combustion chamber. It is also called the gas or pressure ring. The ring prevents combustion gases from leaking. Compression rings also help transfer heat from the piston to the walls of the cylinder.
  • Scraper/wiperring– this is located between the compression and oil rings. It features a tapered surface and serves the function of both rings: to seal the combustion chamber and to wipe oil off the walls of the piston cylinder.
  • Oilcontrolring– the piston oil ring is the lower ring on the piston. It consists of two thin surfaces, with holes all around. The slots allow oil to flow back into the sump. As its name suggests, the function of the piston oil control ring is to remove excess oil from the cylinder walls. It does that as the piston works back and forth.

2. Piston Skirt

Piston Skirt Definition

The skirt of a piston refers to the cylindrical material mounted on the round section of a piston. The part is usually made from cast iron material due to its excellent wear resistance and self-lubricating properties. The skirt contains the grooves to mount the piston oil ring as well as compression rings. Piston skirts come in different styles to suit specific applications.

Piston Skirt Function

The skirt guides the piston as it travels up and down the cylinder.Its design helps the pistonto overcome the side forces created by the changing angle of the connecting rod. If the skirt is worn, obtaining a proper pistonseal for efficientcombustion would prove difficult.

Thepiston would also rock in the cylinder uncontrollably and cause piston slap. When thathappens, you may hear the infamous piston slap noise, especially during cold starts. Piston slap willoften go away after the engine has warmed. That is because the resultingresulting expansion closes the gap between piston and cylinder.

Ifthe noise does not stop, the cylinder may need to be tightened, among othermeasures. Otherwise, the problem does not present much danger, and you maydrive your car if the noise only appears when starting the engine.

There are two main types ofpiston skirts:

  • Full skirt

It is also known as solid skirt. The full skirt features a tubular shape. It is commonly used in the engines of large automobiles.

  • Slipper skirt

The type of piston skirt is used on the pistons of motorcycles and some cars. It has part of the skirt cut away to leave only the surfaces on the back and front of the cylinder wall. This helps to reduce weight and minimize the contact area between the cylinder wall and the piston.

3. Piston Pin

Piston Pin Definition

Also known as wrist pin or Gudgeon pin, the piston pin is the hollow or solidshaft in the skirt section. The piston rod pivots on this pin, held in the piston ring bushing. For tensile strength, piston pins areusually built from alloy steel and machined to fit the piston bearing. Holes in the connecting rod deliver oil to the wristpin, helping to reduce friction.

Piston pin assemblies and mounting styles vary. They can be categorized into 3 designs: free to revolve in both piston and connecting rod, clamped to connecting rod, and rigidly mounted to piston bosses.

Piston Pin Function

A piston pin forms the connection or pivotal point of the pistons andconnecting rod. They provide bearing support and help pistons to functionproperly. In other words, the pin facilitates the back and forth movement ofthe piston.

As we have seen, piston pins use three methods to mount on the piston assembly. These give rise to the following types of pins.

  • Stationary/fixedpin– the pin attaches to the bosses of the piston via a screw. The piston rod then pivots on the pin.
  • Semifloating– the pin attaches to the connecting rod in the middle, and the pin ends move freely within the piston bearing and at the bosses.
  • Fullfloating– in this pin type, the pin is not attached to the pin or piston connecting rod. Instead, it is secured by plugs, clips, or snap ring attached to the piston bosses. The pin can then oscillate at the bosses as well as the rod.

4. Piston Head/Crown

Piston Head Definition

Also known as the piston crown or dome, the headof a piston is its top surface. It is the part that comes into contact with thecombustiongases. As a result, itgets heated to extremely high temperatures. To prevent melting, piston head parts are made using special alloys, among them steelalloy.

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A piston head is usually built with channels and cavities. These help to create a swirl that improves combustion. Different piston head types are used in different engines. Reasons for the differences vary. The preferred piston head design depends on many factors, such as expected performance and engine type.

Piston Head Functions

The crown, as it is also known, forms the surface that takes in thepressures, temperatures, and other stresses of the expanding gases. Among thepurposes it serves are:

  • Creating swirl to make combustion uniform and regulate knocking
  • Act as a heat barrier between the combustion chamber and the lower piston parts
  • Contain the pressures resulting from knock in the cylinder

5. Connecting Rod

Connecting Rod Definition

Often shortenedto conrod or rod, the connecting rod is one ofthe most important piston parts. It links the piston to the engine’s crankshaft and movesthe piston in and out of the combustion chamber. Connecting rods have to bear alot of mechanical strain and should be sturdy enough. For this reason, theparts are mostly forged, although casting is also frequently used.

Automotive piston manufacturers often prefer steel to manufacture these rods. Alloy steel is also a popular conrod material, especially for high-performance engines. For milder engines, aluminum may be preferred for its lightweight nature. The rods of small engines such as scooters can even be made from iron.

Connecting Rod Function

Pistons

Theconrod rotates the crankshaft, producing the motion that enables a vehicle tomove. In some engines, the piston rod features a hole or bore to deliver lubricating oilto the cylinder walls and wrist pin. Manufacturers make conrods in variousdesigns. Versions include cracked joint, milled joint, straight and angledseparation rod, and the parallel and tapered rod design.

Theconnecting rod is divided into several parts. They are:

  • Smallend– it is the smaller end of the rod. It consists of the rod eye and piston bushing. The small end links to the piston via the piston pin.
  • Bigend– the big end is the part opposite the small end of the conrod. It connects to the crankshaft and features a slit design to allow it to be mounted.
  • Connectingrodbeam– this is the section between the small and big parts of the rod. Usually a double T construction, the beam may or may not contain an oil bore to channel lubricant to the cylinder.

6. Connecting Rod Bolt

Connecting Rod Bolt Definition

Alsoin the list of piston parts is the conrod bolt. These bolts clamp the rod to thecrankshaft. The bottom end of rod bolts bolt are rod caps and bearings, held inplace by a nut. A cotter pin on the nut prevents the assembly from comingundone.

Conrod bolts are usually made from steel. In applications where weight reduction is an essential feature, aluminum bolts care common. The rod can also be made from nickel. Nickel connecting rod bolts are stronger and mostly used in heavy-duty rods.

Pistons

Connecting Rod Bolt Function

Aswe have seen, the bolts secure the connecting rod to the crankshaft. They helpthe rod to withstand the strain caused by the rotating crankshaft. In theirabsence, the rod would break down affect the working of other engine parts. The rods guide every pistonstroke, ensuring smooth engine operation.

Conrodbolts are made with the ability to bend a little under the action of the piston and crankshaft movements. Thatprotects the rod caps from collapsing due to the extreme strain caused by themoving crankshaft and piston.

Connecting rod bolts come in a variety of designs. They can be hexagonal, round, flat or an embossed design. Some come threaded others unthreaded. Threaded bolts make the best parts due to their firmer grip.

7. Piston Bearings

The bearings are piston parts that are locatedat the points where pivotal rotation takes place. The are usually semicircularmetal pieces that fit in the bores of these points. Piston bearings include theshells found at the big end where the rod connects to the crankshaft. There arealso bearings at the small end where the rod links to the piston.

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Piston bearings are usually manufactured using composite metals like lead copper, silicone aluminum, and others. The bearings are often coated to improve hardness and enable them to bear the load of piston and connecting rod movements.

Piston Parts Questions

1. Do engine pistons havereturn springs?

No, they do not. A piston return spring is not required in these pistons. However, you will find the springs in drum brake assemblies. Here, they help to retract the brake shoes when you release the brake pedal.

2. What is pistonliner?

It is a kind of liner installed on the walls of an engine cylinder.Usually made of superior material than that of the cylinder bore, the linerprovides a hard-wearing surface. Car owners install it to either protect thecylinder or repair it when rebuildingthe engine.

Because the liner is replaceable, using it increases engine life. A piston liner is also called piston sleeve and does not form part of piston assembly. You will also find it going by the name cylinder liner or sleeve.

3.What piston parts canbe replaced?

Most piston assembly components can be changed. They include piston rings, piston bearings, piston rod bolts, and several other parts. Thesecan be purchased individually or as a piston kit.

Piston rings wear quickly. They are one of the most replaced piston parts. When damaged, these rings cause various piston and engine problems. That can lead to extra costs. Given that the piston ring price is only a few hundred dollars, replacing these parts can save you from expensive repairs.

4. What is the cost ofreplacing pistonparts?

The amount can exceed $1000 or even $2000. Piston kit price or that of individual components may be low, but notso the amount you pay a mechanic to do the job. Replacing anything hiddenwithin the engine block involves several hours of work, which iswhy it costs a lot.

Add that to the fact that there is usually a pistonset to change, and the amount can be pretty high. You canchoose to replace the piston or piston parts yourself, of course. However, youwould need the right tools, which include the following:

A piston ringcompressor to install therings, a micrometer to pistonmeasurement, and a feelergauge set to measure piston and piston ring clearance. You may also need a piston ringfiler to hone the rings to thecorrect specifications. You also need to understand how to replace the pistoncorrectly. (we have a whole article dedicated to piston installation process). There are many piston types on the automotive piston market.

To find the right one for your engine, scour the websites of manufacturers. They usually provide an automotive pistons catalog. These contain invaluable information regarding the specific piston you may be looking for. That includes piston size chart for piston to cylinder clearance, piston depth chart, and more. You will also have the chance to piston price across sellers.

Conclusion

Havinglooked at piston parts,you now know how eachcomponent looks like as well as its location on the piston assembly. We have more articles on the automotive piston and youcan browse through them. The articles cover several topics, including piston measurement when rebuilding your engine. And iflooking for the right piston for your car engine, we have a full-length articleabout piston types.

Having determined what sort of material best suits your needs/application, the main design and detail features of the piston now need consideration. The over-riding factor that influences just what is best for an A-Series engine is the block's propensity for flex at higher rpm, and the crank's equal propensity for flex at the same sort of rpm levels. Both combine to require a piston that is as stable as possible to maintain effective and consistent ring-seal performance. Reduced ring seal equals dramatically reduced performance. And none of this is at all helped by the relatively enormous distance from the wrist pin centre to crown height on most A-series pistons.
Overall shape
For the longest time, pistons were made round (well, 'ish' anyway) and straight sided (again - 'ish' is applicable here too) to form a cylinder, the top closed in to retain the all-important fuel/mixture charge; mainly because this was the simplest shape that would fill/block off the cylinder (bore) in an engine to greatest effect for minimum outlay. The irrepressible march forward of technology soon came into play though, finding gains to be made in certain applications if the piston was made a slightly different shape, and weight savings allowed higher rpm to be achieved reliably. And with it came more bhp. It didn't take long for the step to more efficient position shapes to be used for maximising performance and economy in road engines either.
Just for the record - the 'ish' business described above refers to the fact that pistons are rarely either straight (parallel) sided, nor round. They are machined like this to compensate for the massive running temperature differences between the crown and skirt, and pin axis to open skirt area - the pistons crown being the smaller end of a tapered shape.
Perhaps the 'peak' of piston design is the current race-type items as used by the likes of F1, etc. - what amounts to little more than a large disc joined to the con rod by a short 'tail', having only two piston rings (one compression one oil ring) and weighing only slightly more than yer average feather. You have to see/feel one to appreciate the design - based on what has become commonly called a 'slipper' piston. Not because it looks like your fireside 'comfies', but because of it's low-drag design having no sides to speak of making if very 'slippery' in use. A feature carried over into the road-car market and after-market performance pistons. The Mini/A-series being no exception.
The first pistons available in this 'T' shape were manufactured for Abingdon ST for Mini Miglia/998cc engines. A pukka forged slipper piston made by Cosworth. You had to use S rods with these though as no sides precluded circlip or button retention for the wrist pin. The main hassle here was having to assemble the piston to the rod, remove the rings, feed the piston in from the bottom of the bore, then poke the piston out the top of the bore, and re-assemble the rings before making fast with the ring clamp to actually finally fit the assembly complete back into the bore. Strip down was the exact opposite. A fair bit of hassle.

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Latter days saw the introduction of the slipper shape to the A+ engines, first fitted to the Metro, in an attempt to reduce piston drag/weight to maximise performance and economy for the road engines. It wasn't long before folk started using them in performance street and competition engines - believing what's good for the likes of F1 must be good for the A-series. Much in the way many other performance-related items have been applied from one automotive application to another entirely different one without any real understanding of the subject, consideration or testing/development work.
To cut this long story short - remember what I said right at the start about bore and crank flexure? F1 engines have supremely stiff block assemblies with very short-stroke, supremely stiff crankshafts. They simply do not suffer from flexure to a degree that affects ring seal at high rpm (and we-re talking 18,000rpm here). Even when considering the fact the engine and gearbox assembly is what they call a 'stressed member' - it carries the whole of the rear suspension as well. The A-series doesn't enjoy anything like this stiffness.
I am not saying the current crop of slipper pistons are a waste of time in an A-series. They are perfectly capable when used in a situation they were designed for. And I have used them (the MG Metro versions - the best of the bunch construction-wise) in race engines with success. It's just not the best option for our venerable A-series. This was recognised by Rover when they went into production of the Metro Turbo engines, and latterly the injection Mini engines where full-skirt pistons were used.
So - where an option exists a full-skirt piston is likely to produce more effective and more consistent ring seal, especially at higher rpm than a slipper type because of the crank/bore flexure problem. And this is anything over 6,500rpm on a regular and protracted basis, i.e. not just a quick 'visit' to that rpm peak on an odd occasion.

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Rings and ring lands

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There are a couple of items to note here - ring pack position and oil drain facility.
Most modern pistons have the ring packs and position on the piston pretty much sorted out. It is worth knowing that the ideal distance from the top ring to the piston crown on an A-series engine is around 7mm. Higher than this and damage from combustion is likely, lower and detonation can be caused by excessive amounts of un-burnt fuel collecting here ignited by incorrect ignition timing. This was (and is) the Achilles Heal of the 73.5mm/74mm Powermax piston for 1380/1400cc engines. The top ring is too far down the piston. I'd like a pound for every time I've seen these pistons with detonation damage around and above the top ring.
Oil drainage from the oil ring land area should preferably be by drilled holes as these can be angled to best use and minimise weakening of the piston. This form of oil drainage is one of the 'must have' features for a high performance piston. Unfortunately this isn't practical on mass-produced 'standard' engine pistons. Standard production pistons tend to have slots machined along the back of the ring groove at 90 degrees to the wrist pin axis and is also seen as a way to make the piston run 'quieter' by damping out resonance in it. Perhaps the most extreme example of the slotting method of quietening pistons is seen on the very old 803cc/850cc specimens where a 'T' slot was machined into one side of the piston skirt.
Whilst not ideal, slots certainly aren't a huge problem where high performance is planned - providing the slots are not excessively long. A slot that gets anywhere near, or even encroaching into, the pin boss supports/struts should be completely avoided for performance use. These are likely to severely weaken the pin boss, causing the piston top section to detach from the skirt at this point - two-piece pistons make a real mess of the rest of the engine!
Modern piston rings are generally now settled into a regime of high quality materials and production. Widths are distilled down into certain operating envelopes. Although 1mm width rings are used by some race piston manufacturers (seen as a way of reducing the phenomenal amount of friction/drag developed by the rings, some 70-75% of the total internal friction developed within an engine), 1.2mm rings are optimum for the A-series. Consequently this width appears on all well developed A-series performance pistons.
Wrist (Gudgeon) pin
Covered in 'Pistons - Why's and wherefores' all I'll add here is the most common type used in a majority of standard production pistons has a very thick wall with parallel-bored centre hole. Grossly over-engineered to easily cover 100,00miles without failure, simple and cheap to manufacture. But very heavy. Ideal solution is a much thinner-walled parallel-bored pin in superior material - light but expensive to manufacture. Best halfway house is a pin with tapered-bore ends. Enough said on that subject.

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However - of worthy note is the oiling system used. Oil splash from the thrashing engine internals provides superficial lubrication, but on a high performance piston something more is definitely required. 'Old' technology usually saw lubrication provided from behind the oil ring land, fed down onto the top of the pin (12 o'clock position viewed side on and crown upper-most). However, intensive development by major piston manufacturers identified this as a problem area, since the piston was under load at this point for a considerable amount of time - some 70%-worth, therefore limiting oil feed/lubrication of the pin. A consequence was rapidly worn pin bores in the pistons - and in the case of our A-series motors even more piston instability. To solve this problem, it has been found that two slots along the bore length at the 10 and 2 o'clock positions are far superior since these areas are under more or less no load all the time.
Mini Spares 'mega' piston range
Desperately inconsistent supplies for protracted periods of performance Mini pistons and the relatively 'ancient -' although it has to be said, 'pretty capable' - piston over-all design caused Mini Spares Centre to concentrate a fair amount of effort into developing the ‘MEGA’ piston range to try and resolve all these problems in one fell swoop.

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Recruiting the AE Hepolite Group for their unquestionable and renowned design and manufacturing expertise, the goal was to produce the most robust piston possible given reasonable cost and weight limits. Applying current technological advances incorporating their very latest hi-spec AE109TF lightweight alloy and special double heat treatments, the result is an extremely durable piston that will withstand greater cylinder pressures at higher rpm than any other currently available.
To simplify the range, material has been concentrated around previous problem areas – the ring lands and crown – providing one crown height. This ensures sufficient material in critical areas to allow machining where long stroke cranks or longer con rods are used. The design guards against premature damage from poor/low quality modern fuels, the rings re-sited to minimise detonation damage in high compression engines. The ring dimensions are compatible, and therefore interchangeable, with the Omega Mini piston range. Full-circle skirts are used for maximum piston and ring stability. They also feature a specifically designed ridged finish to retain oil to protect against scuffing and galling at start up and cold running. A tapered pin is employed to maximise stiffness against lightest weight. In all - utilising all that technology and development has identified as necessary in a performance piston for the A-series engine.
The only downside to this is the fact that they are only available for the large-bore engine types. Insufficient demand and stupendous manufacturing investment costs have precluded manufacture of a range for the small-bore units.
For further information, see 'Pistons - Whys and wherefores'.
For a list of pistons available, see the inventory section under pistons.