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Under Review | Djt and dst: the non-shifter engines according to vortex

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Like most kart engines on the market. 4-stroke engines are still a small niche

125 cc

125 cc has been the standard for some time now, while in the past it used to be 100 cc


Push-mode made easy thanks to a decompression valve on the cylinder head that helps the piston


The following are the “families” of kart engines: gears and single speed. The DJT and DST are single speed clutchless engines


It is the OK and OKJ, effective from to 2019 to 2021.

The 2019 season ended with an important title for Vortex, the engine division of the OTK Kart Group, which achieved the first step of the podium of the FIA Karting Junior World Championship with Thomas Ten Brinke. Empowering the Dutch driver was the DJT engine, introduced by the company during the 2019–2021 homologation cycle together with the DST engine, destined for the OK class.

Both models are part of the wide-ranging project which the company is planning for the FIA non-shifter categories. After the first homologation cycle started in 2016, the intent is to gradually work on all of the engine’s areas with the objective of obtaining a simpler, repeatable, reliable but also better performing product

With the DJT and DST engines this intention is established, first of all, in a complete overhaul of the entire engine’s crankcase, intended as the crankcase assembled in all its components, which is completely different than that of the previous model. The technical innovations involve every aspect, from the molds to the casting, the machining, the dimensions and the even smaller componants.

The basic ideas which dictated all the changes are rather simple, starting from the need to have an engine with a lower center of gravity.


    From the cylinder upwards, the DJT and DST are identical to their predecessors, the DDJ and DDS

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    The fins of the cooling channels increase the heat exchange surface between the fluid and the cylinder

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    Both the DJT and the DST benefit from a new piston, redesigned on the intake side

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    The crankcase side transfer ports have been optimized to improve the engine’s behavior at low and medium RPM

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    DJT and DST have the same reed valve pack which has different stoppers than the previous model

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    The Vortex technicians guarantee that the lowering of the center of gravity is substantial and required considerable work during the design phase to decide which masses to move, rotate or resize to make sure that the equivalent center of gravity of the engine would result in being closer to the ground.  Clearly, a repositioning of the center of gravity does not provide extra horsepower, yet it certainly helps in making a better use of those that are already there, by improving the handling thanks to reduced pitching and rolling movements. Through this improvement, even without touching the thermal parts of the engine which remained the same as the previous homologation, it was possible to make a decisive step forward in terms of performance.

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