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Piston pins
Small but extremely important
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A piston is only as strong as its piston pin
Although piston pins are small and inconspicuous, they still play a crucial role in the distribution of forces within your engine. We can even say: a piston is only as strong as its piston pin. Here, you will find out what this little part does and why it is so important for tuning.
CONTENT
- 1. How does the piston pin look?
- 2. What is the function of the piston pins?
- 3. Mounting the piston pins
- 4. What damage can occur if you make a mistake installing the piston pins?
- 5. Coating of piston pins
- 6. Do you need help with installation?
- 7. You want to know more about piston rings, piston coating etc.?
How does the piston pin look?
A piston pin looks like a hollowed-out pin and has either a consistent cross-section or is additionally reinforced (like our reinforced turbo piston pins). Particularly in motorsport, there is an increasing number of piston pins that are conical on the inside and thus very lightweight. The pin ends then have a lower wall thickness than the highly stressed centre. Pins with chamfers are also very popular, especially in series production. The sloped surfaces at the edges reduce the weight, which advantageous not only for tuning. The challenge here, however, is to design the piston pins with sufficient strength.
What is the function of the piston pins?
The piston pins connect the pistons with the connecting rods and thus transfers the forces between pistons and connecting rods. Gas and mass forces, in particular, have a strong impact on the pin, which is why it absolutely should be reinforced with increased performance. Piston pins should ideally be designed with a low mass. Usually, the piston pin is floating in the small end of the connecting rod or in the piston boss (or in both) and has little play there. Because the piston pin is subjected to extreme strain, it is also manufactured with the most exacting demands in terms of precision. It must be perfectly round, fitting the cylindrical shape, and its dimensions must be in relation to the diameter. If the pin were to get jammed, this would quickly cause your engine to break down. That’s why the pins also play an important role in tuning, because then particularly high forces are exerted on the little pin.
Mounting the piston pins
First, the connecting rods are checked for bending and arranged with the pistons in the direction of installation. Next, you oil the pin and then carefully insert it into the small end of the connecting rod and the piston pin bore in the piston. In some cases (with pins whose bore has a tight tolerance), it may prove helpful to slightly heat up the pistons.
To prevent the pin from starting to move and thereby damaging the cylinder wall, it is fixed in place in the piston pin bore. This is done with piston pin clips, also referred to as circlips, for which there is a groove in the piston pin eye. The ring must engage completely in the groove. You can tell whether this is the case by rotating the rings slightly.
The clips have to be fitted using a suitable tool and must never be pressed together excessively. This may cause permanent deformations, causing the circlip to not be sufficiently tensioned. Make sure that the end gap of the clips is always in the direction of the piston stroke and that the pistons and connecting rods are assembled in the specified direction of installation.
What damage can occur if you make a mistake installing the piston pins?
If the pistons and connecting rods are not properly connected by the piston pin, this can result in severe damage. These include, for example:
- piston seizures
- erosion on the piston pin bore
- damage to the cylinder bore
- high oil consumption
- drop in performance
- overheating
- engine noise
To avoid this damage, you should therefore have a delicate touch when installing the pins. Remember to replace wear parts such as the circlips and not reuse them.
Coating of piston pins
In order to reduce friction and wear and thus also fuel consumption and pollutants emitted, it is becoming increasingly common to apply a coating to the piston pins. Carbon coatings such as diamond-like carbon (DLC), for example, may be used. These diamond-like carbon layers give the piston pins an extremely hard surface, even though the coating is very elastic. This significantly reduces the friction between the pins and connecting rods and enhances the dry-running properties.
Do you need help with installation?
You shouldn’t take any risks when installing pins. Get help from our motorsport pros. Just contact us via chat and make an appointment.
You want to know more about piston rings, piston coating etc.?
Here you will find everything you need to know:
Optimal pistons for your engine tuning
His first car was a Polo Mk1 with a 40 Weber twin carburetor and 129 PS (95 kW). His second was an Audi 50. Today Bartek tunes Lamborghinis to 1000 PS (735 kW). Even as a young boy, Bartek disassembled vehicles and put everything back together better. He wrote his high school diploma with oil on his fingers. The trained automotive mechanic with a focus on engines and gearboxes was determined to go into motorsports. In his 10 years in Formal 1, he supervised 73 races, including as engine mechanic for Ralf Schumacher at Toyota. Since 2010, he has dedicated himself fully to his company BAR-TEK® and helps his customers to bring VW and Audi engines to peak performance.
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Comments
Javier
18.11.2023, 11:45 Uhr
Hi, I need the tools for install pistóns pins, can You send the link thanks You
