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ST4 BTM aero rules clarification for hood and bumper cooling mods

codename Bil Doe

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  • National Staff


Here a the most basic and common example of a hood air dam.


Here is a roof air dam:



Here is a front wing off a hood:



Here are a few more front wings/spoilers, etc.







The point being, that we want aero to be simple in ST4-6.  We don't want our competitors to need wind tunnel testing to be competitive.  We don't want them to have to fabricate some crazy "hood vent" that functions as some type of air dam or airfoil, etc.


However, this discussion has proven the point that regardless of our best intentions to keep the rules to common sense with the function of permitted modifications listed (when they are not unlimited), that we will need to forever keep expanding the rules with specification after specification.  If I was to write a truly 100% specified rule for just this hood vent modification, it could literally be a paragraph long--multiply that by all of the rules, and end up with 100 pages of nothing anyone wants to read.  But, we will put some type of revision on this in the upcoming revision of the ST Rules.

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My opinion is that the rule could remain as is, and OP can still vent his hood.

”The hood may be modified for venting”

that’s a pretty open rule to allow whatever kind of venting hardware you want.  As long as modification is only for the purpose of venting the hood, he’s fine.

If someone put a spoiler on the hood and claimed it helped venting - well, sorry, its not just performing venting.

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I think you just said the word this is all going around. Venting / Vent.  Whats a vent?  is a hole a vent? is a louver a vent? how about a lip on the front of a louver? is a tall piece of molded plastic like those dmax things a vent?  The current rule imo is no limits on vents, the rule makers think otherwise, this leaves to much guess work as to whats allowed and not allowed. A simple size limit LxWxH seems good to me, anything that can fit in there is fair game. simple easy and sets a limit.  Everything else in the rule book has size limits. I am glad to see the rule makers want to clarify this, I just hope they do it sooner than later so I can get on with my project and so others can be legal for there next track event.

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