The Engine Technology in Boukenger

Boukenger has been having mysterious engines known as Parallel Engines.
As we know, the Parallel Engines were used on ALL their mecha.
They were written during the middle ages by Leon Giordana, the very basis for the parallel engines. However Gaja found these records and devised a counter engine known as the Gordom Engine.
Gaja's first application of the Gordom Engine was on the Ashu warriors Gai and Rei and transformed them into Questers. They became so powerful that their suits could harm the Boukengers when the engines activate.
However the SGS had a trick of its own- by modifying the design to go against the Gordom Engine. This power first went to Eiji Takaoka before the rest were given adjustments. It was but fitting for the storyline because he had a long time fight with the Ashu. However only Bouken Silver was extraordinarily fast from them.
The Siren Builder was technically the first robot used by SGS to use the Neo-Parallel Engines to counter the Gordom Engines.
Gaja managed to make use of the technology once more by creating another Mirage Beast through putting a Gordom Engine into the Lemurian Egg. When the engine it destroyed, it grew giant and was out of control.
The evil machine dragon Brand used the Gordom engine as Ryuon planned with the Questers. It was in fact terrifyingly powerful but was defeated by the Dai Voyager.
Perhaps the last application in the series was when Gaja used the Gordom engine into himself to become more powerful. He was defeated but not killed for some reason. However it's not likely he'll return if the Gordom Heart got destroyed which apparently allowed him to rise from death to conquer the world.