Not legal 1 class
Prohibited. · DD.7
IHRA · Forced induction
Aftermarket supercharger
IHRA answers this part for 24 of its classes. 13 of those answers are permissions, with or without limits attached, and 11 are not. 10 are inferred from how the class is written rather than quoted from a rule naming this part.
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.
Not permitted, not listed in the rules Our reading, not a rule we can quote at you. This class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list.
No rule, this is an open class Our reading, not a rule we can quote at you. This class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms.
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, within limits 1 class
Clutch may be aftermarket if readily available to all competitors from a reputable manufacturer. Kawasaki Ultra 300/310: pulleys and tensioners modifiable. Yamaha SVHO: supercharger shafts may be welded. · W.3.6
Legal, within limits 1 class
Components may be reinforced for safety. Replacement parts allowed but original gear ratios must be maintained. · Y.6.1
Legal, within limits 1 class
Reinforcement for safety only. Original gear ratios must be maintained. · Z.9.1
Legal, within limits 1 class
The impeller must be OEM and unmodified, aftermarket shafts and rebuild kits are permitted, there is no re-gearing, and Yamaha models may not use older centre gears to alter OEM ratios. The housing rule contradicts itself in the same bullet, permitting front and rear housings to be OEM or aftermarket and then requiring gearing and housings to remain OEM and unmodified. Both are printed and neither is withdrawn. · DD.1
Legal, within limits 1 class
Aftermarket wheels permitted but the system must retain the OEM-style gear drive off the flywheel at the PTO. Water cooling permitted. · DD.2
Legal, within limits 1 class
Impeller may be aftermarket. Front housing OEM or aftermarket meeting OEM spec. Gearing must remain stock, no re-gearing, no older center gears. · DD.3
Legal, within limits 1 class
Must retain the OEM-style gear drive off the flywheel at the PTO. · DD.4
Legal, within limits 1 class
Four-stroke entries: IMPELLER HOUSING MUST REMAIN OEM. Internals, pulleys, tensioners, intercoolers may be aftermarket. Spacers allowed for a larger impeller. Oil line fitting may be added to the shaft. · BB.6.1
Legal, within limits 1 class
Engines 1100cc or less only. · K.5.1
Legal, within limits 1 class
Four-stroke entries: Limits: max displacement 1100 cc. · V.6.1
Legal 3 classes
Aftermarket permitted.
- Drag, Super Stock · DD.5
- Drag, Stand Up Unlimited · DD.10
- Runabout GP · X.4.1
No rule, this is an open class 1 class
No restriction in section CC, and CC.1 permits any modification it does not restrict.
- Freestyle · CC
No rule, this is an open class 1 class
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, Unlimited · DD.6
Aftermarket supercharger: 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 · signed checks on parts the shop sells.
Forced induction · four stroke · legal outright in 13 of 24