IJSBA · Driveline

Aftermarket impeller at OEM diameter

Legal in every class that addresses it, but diameter is the constraint in stock tiers.

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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.

For every stock class, publish the impeller's diameter next to the OEM diameter. That one number decides legality.

Where it stands, class by class

20 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.

Legal, within limits 4 classes

Permitted subject to the universal limits in ijsba-globals.yaml constants.

• Fixed Steering Ski Stock · FSSK
• Four Stroke Ski Lites · FSKL
• Runabout Naturally Aspirated · RNA
• Ski Lites · SKL

Legal, within limits 1 class

RRL.6.1

• Runabout Rec Lites · RRL

Legal, within limits 1 class

Modified or aftermarket impeller retaining ORIGINAL DIAMETER. · SSK.6.1

• Ski Stock

Legal, within limits 1 class

RAS.10.1

• Runabout Stock · RAS

Legal, within limits 1 class

Must come from an IJSBA-APPROVED aftermarket manufacturer. · SKM.9.1

• Ski Modified

Legal 10 classes

Explicitly permitted by this class document.

• Sport Spec · none - this document uses ALL-CAPS section headings, not numbered rules
• Runabout Limited · RAL
• Vintage SC · VSC
• Vintage X2 · VX2
• Runabout Superstock · RSS
• Vintage Ski · VSK
• Freestyle · FREST
• Ski Grand Prix · SKGP
• Sport GP · SPGP
• Runabout Open / GP · ROP

Legal 1 class

VSKL.6.1

• Vintage Ski Limited · VSKL

Legal 1 class

Diameter constraint lifted. · SKSS.6.1

• Ski Superstock

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Aftermarket impeller at OEM diameter: 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 IJSBA class · where the rulebooks differ · signed checks on parts the shop sells.