Tech Focus | As transparent as… A Righetti Ridolfi pump

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AS TRANSPARENT AS... A RIGHETTI RIDOLFI PUMP

Carlo Forni

21 April 2017

With the goal of optimising racing engine temperatures, Righetti Ridolfi, a leader in the design and construction of pumps for cooling water systems, has introduced the new K518TR. Distinguishing features: transparent

The performance of two-stroke racing engines, such as mounted on karts, is closely related to operating temperature. Temperatures are regulated mostly by the water system, the configuration of which is one of the key aspects that allow the cooling of the hottest areas, such as the side of the cylinder exhaust duct and port, side and the drainage duct of the cylinder. In order to achieve optimal engine operating temperatures for both performance and reliability, merely cooling “as much as possible” is not enough, it has to be done properly.

RR RESEARCH AND DEVELOPMENT

With the switch from KF engines to the current OK engines, water pumps have been moved back to the outside of the engine, as was the case in the 100 cc era. This greatly simplifies control and makes their replacement much faster; on the other hand, however, the new pumps requires a specific design. Righetti Ridolfi did not duck the challenge, but designed and produced a brand new water pump, derived from the previous K698 model, which stands out due to its design and the materials used, as well as promising greater efficiency.

COOLING

As mentioned, efficient cooling is critical to the performance and reliability of an engine. Temperatures that are too high can lead to detonations in the combustion chamber resulting in seizure or the simple loss of performance. This is also the reason why, for example, it is often the case that an engine that performs well during the initial laps of a race gradually loses power and torque due to increasing temperatures and changes in the tolerances between elements such as the cylinder and the piston. However, low temperatures are also not good, since they cause variations in the mixture vaporisation phenomenon and, also in this case, loss of performance.

RIGHETTI RIDOLFI IS AMONG THE MOST RENOWNED MANUFACTURERS OF KARTING ACCESSORIES IN THE WORLD. IT HAS OVER 1,100 STORES IN 87 COUNTRIES AND OFFERS A CATALOGUE WITH MORE THAN 2,700 ITEMS, MOST OF WHICH ARE MANUFACTURED DIRECTLY BY THE COMPANY

THE PROJECT

To optimise the flow of water from the radiator to the engine, Righetti Ridolfi has worked on both the efficiency of the flow in the system’s tubes and on the characteristics of the pump impeller. Regarding the first aspect, the goal was to reduce flow losses as much as possible, eliminating some of the narrow bends in the tubes that were necessary in previous pumps. To do so, the company took a bold and courageous decision: to reverse the direction of rotation of the impeller. The solution allowed the water inlet and outlet ducts from the body of the pump to be inverted, turning the inlet towards the radiator and, consequently, eliminating the special and inefficient elbow tubes.

THE IMPELLER

The other fundamental aspect of the Righetti Ridolfi project, as mentioned above, was the complete redesign of the impeller, designed to improve the flow rate especially at low engine speeds. In fact, it should be remembered that it is precisely at low speeds that the water flow rate drops considerably and even if the engine is under less stress, the air flowing onto the radiator is reduced and, therefore, the water in the cooling system nevertheless rises in temperature. Not only that, low temperatures at low engine speeds must remain low, otherwise there will be an expansion of the engine components, such as the cylinder, resulting in a loss of compression and thrust at low engine speeds, when compression is a key factor.

The flow rate of the new K518TR pump is better than the previous K698 model, especially in the 2500-4000 range of revolutions (pump rpm). Indicatively, the percentage improvement of the flow rate is equal to 6%. The maximum flow rate is 28 litres/minute

MATERIALS

The material of the new K518TR pump is a compound developed exclusively for Righetti Ridolfi: extremely resistant to solvents, high temperatures and even knocks. It is the same compound used for the KB030 brake pump tanks, also produced by RR. Transparency also allows a better visual inspection of the inside of the pump and an easier assessment of the integrity of the components. The impeller, on the other hand, is made of glass-fibre reinforced PA66 polyamide material.

The transparent body version of the new K518TR pump is undoubtedly very eye-catching. It is also available in black

SIZE AND WEIGHT

The diameter of the body of the pump is 66 mm and the width is 37 mm. The diameter of the impeller, on the other hand, is 42 mm and the width is 19 mm. As for “equilibrium”, the new K518TR pump weighs 193 g. The body, alone, weighs 65 g and the impeller weighs 44 g. Compared to the previous model, the use of new materials has reduced the overall weight of the pump by 10%.