Aftermarket flame arrester, IHRA

IHRA answers this part for 29 of its classes. 0 of those answers permit the part outright and 18 permit it with stated conditions, leaving 11 that do not. 3 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.

Where it stands, class by class

29 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

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.
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.

Not permitted, not listed in the rules 8 classes

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

Legal, with conditions 7 classes

The class requires a flame arrester meeting USCG, UL-1111 or SAE J-1928 rather than the OEM one, so a compliant aftermarket arrester reads as allowed.

Runabout Endurance · W.3.2
Four-Stroke Ski Lites · N.3.1
Ski GP2 · L.3.1
Ski 1100 Modified · R.3.1
Ski 1500 Modified · Q.3.1
Freestyle · CC.3.5
Runabout GP · X.3.2

Legal, with conditions 6 classes

An aftermarket flame arrester is allowed if it meets USCG, UL-1111 or SAE J-1928 Marine standards.

Ski Lites · O.3.1
Sport Spec · U.3.2
Ski GP3 · M.2.2
X2 Vintage · T.3.2
Ski Vintage · S.3.2
Sport GP · V.3.2, V.5.2

Legal, with conditions 3 classes

Every engine must run a flame arrester meeting USCG, UL-1111 or SAE J-1928 rather than the OEM one, and where a ribbon is the OEM arrester it may be removed if airflow does not increase and the air filter still suppresses flame.

Runabout Lites · AA.3.1, AA.3.2
Runabout GP2 · Y.3.1, Y.3.2
Runabout GP3 · Z.4.1, Z.4.2, Z.5.1

Legal, with conditions 1 class

Model-dependent. Both engine types may run a flame arrester meeting USCG, UL-1111 or SAE J-1928, but a four-stroke entry keeps the intake manifold, screens and spark suppressors stock behind it (N.3.1), while a two-stroke entry may fit an aftermarket arrester (O.3.1) and may also change its carburetors and intake manifold under P.2.4. · N.3.1, O.3.1, P.2.4

Ski Limited

Legal, with conditions 1 class

Four-stroke entries need a flame arrester meeting USCG or SAE standards and carbureted ones an arrester meeting safety standards, while two-stroke entries may fit an aftermarket arrester meeting USCG, SAE J-1928 or UL-1111. · BB.4.1, BB.4.2, BB.5.3

Runabout Limited

No rule, this is an open class 3 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.

Aftermarket flame arrester: 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.

Fuel · two and four stroke · legal in 18 of 29 answered, all with conditions