Rallycross regs are complex and as a result there are specific engine specifications engineered to suite those regulations. As a result you see "unusual" hardware that is designed to specifically overcome some limitations imposed by the regs. From memory the VW's ran in the category that mandated restrictors of a predetermined size. One of the engineering solutions to help with overcoming the limitations of a restrictor is to make the inlet plenum as large as possible, kind of like a boost storage tank. This helps with maintaining boost while playing with the throttle opening to control the traction. It also delays the response on rapid throttle opening a little to avoid the car breaking into uncontrollable wheelspin. All rather specific rallycross requirements that are not exactly desirable in circuit race cars.
That's why circuit/track cars have the throttle bodies as close as possible to the inlet valves, as we want instantaneous throttle response. Hence the need for multiple throttle bodies.
Cheers
Gary
Last edited by Sydneykid; 10-02-2020 at 12:15 PM.
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