IHRA · Fuel

Aftermarket throttle body, IHRA

IHRA answers this part for 24 of its classes. 1 of those answers permit the part outright and 5 permit it with stated conditions, leaving 18 that do not. 2 of the ones that do not are classes we read as open rather than as refusing it. 11 are inferred from how the class is written rather than quoted from a rule naming this part.

This page is IHRA only, and the bodies do not agree. The same part under IJSBA and UIM. Which one applies to you is decided by whoever sanctions the race you enter.

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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. If you race more than one series, build to the stricter answer. The differences are set out in the rulebook comparison.

Where it stands, class by class

24 classes, grouped where the same rule gives the same answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.

What each answer below means

OEM part required

This comes off. Only the part the manufacturer fitted is allowed here.

Not permitted, not listed in the rules

Treat it as coming off. The class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list, so this is our reading rather than a rule we can quote at you.

Legal, with conditions

Keep it, but measure it: the rules permit this part only inside stated limits.

Legal

Keep it. The rules permit this part in this class.

No rule, this is an open class

Probably keep it. The class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms, and this is our reading rather than a permission anybody wrote down.

OEM part required 2 classes

Must remain OEM. No modifications to the throttle plate or housing.

• Ski 1100 Modified · R.3.2
• Ski 1500 Modified · Q.3.2

OEM part required 1 class

Must remain OEM. Interchangeable between WaveRunner models. · DD.1

• Drag, Yamaha Pro Stock

OEM part required 1 class

Must remain OEM. Cable-driven bodies may be bored to latest-model specifications. · DD.2

• Drag, Sea-Doo Pro Stock

OEM part required 1 class

Must remain OEM. · DD.3

• Drag, Yamaha Spec

OEM part required 1 class

Must remain OEM. Cable-driven bodies may be bored to newer-model Sea-Doo specifications. · DD.4

• Drag, Sea-Doo Spec

OEM part required 1 class

Must remain OEM. Four-stroke entries: No modifications to throttle plate angles or housing. · BB.4.3

• Runabout Limited

Not permitted, not listed in the rules 9 classes

On a closed list an unlisted modification is not permitted. · A.2.2, J.1

• Runabout Lites
• Four-Stroke Ski Lites
• Runabout GP2
• Runabout GP3
• Ski GP2
• Drag, Sea-Doo vs Sea-Doo
• Ski GP3
• Ski Limited
• Drag, Turbo No Nitrous

Legal, with conditions 2 classes

Butterfly count must not exceed cylinder count.

• Ski GP · K.4.1
• Runabout GP · X.3.3

Legal, with conditions 1 class

Yamaha SVHO: Aftermarket throttle body adapters permitted. · W.3.4

• Runabout Endurance

Legal, with conditions 1 class

Butterfly count may be increased but must not exceed cylinder count. · CC.3.6

• Freestyle

Legal, with conditions 1 class

On four-stroke entries the butterfly count must not exceed the cylinder count. · V.5.3

• Sport GP

Legal 1 class

Aftermarket throttle bodies are permitted, with no butterfly count or bore limit stated. · DD.5

• Drag, Super Stock

No rule, this is an open class 2 classes

The class states only what it bans and calls itself run what you brung, against a section DD preamble that says anything unlisted is illegal.

• Drag, Stand Up Unlimited · DD.10
• Drag, Unlimited · DD.6

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Aftermarket throttle body: 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 IHRA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.