UIM · Forced induction

Boost relief / overboost control valve

UIM answers this part for 24 of its classes. 0 of those answers are permissions, with or without limits attached, and 24 are not. 8 are inherited from a parent class the rulebook points at.

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This is one body's answer, not the sport's. You are bound by whichever body sanctions the event you enter, and where both govern you, you are held to the stricter of the two. The differences are set out in the rulebook comparison.

UIM requires no boost relief valve anywhere. IJSBA requires an approved one in Ski GP and Sport GP. Do not carry the IJSBA requirement across.

Where it stands, class by class

24 classes, grouped by the answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules. 8 of them publish no component rules of their own and are marked below; for those, the link to the parent class is read from the categories table rather than stated in the rulebook.

Not legal 9 classes

Explicitly prohibited by this class.

• Runabout GP4 · 502.01
• Ski Division GP4 · 501.01
• Runabout GP3 · 502.02
• Ski Division GP3 · 501.02
• Runabout Juniors GP4 · 302.01 · borrows another class
• Runabout Ladies GP4 · 302.01.01 · borrows another class
• Ski Juniors GP3.2 · 302.01 · borrows another class
• Ski Juniors GP3.3 · 302.01 · borrows another class
• Ski Juniors GP4 · 302.01 · borrows another class

The rules do not say 5 classes

No boost article.

• Ski Division GP1 · 501.04
• Runabout GP1 · 502.04
• Runabout Veterans GP1 · 302.01.05 · borrows another class
• Ski Ladies GP1 · 314 · borrows another class
• Ski Veterans GP1 · 302.01.05 · borrows another class

The rules do not say 1 class

The Overboost Control appendix referenced at 502.03.04-09 does not exist in the document.

• Runabout GP2 · 502.03

The rules do not say 1 class

Not stated. The HSR-Benelli figure is a boost limit, not a valve specification.

• Ski Division GP2 · 501.03

Governed by the parent class 8 classes

No component rules are published for this class and no single parent class is named, so this part cannot be answered for it. That is an absence in the rulebook, not a permission.

• Endurance · 317.03
• Freestyle Amateur · 312
• Freestyle Free · 312
• Jet Raid · 317.01
• Offshore · 317.02
• Parallel Slalom · 313
• Ski Future Electric (SFE) · 302.01
• UIM Hydro-Fly · 900

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Boost relief / overboost control valve: if the rule your class applies reads differently to you, or the rulebook has changed since this was read, ask. We answer with the section we read it from, or that we have not read it. Ask a rules question.

Every UIM class · where the rulebooks differ · signed checks on parts the shop sells.