IJSBA · Driveline

Aftermarket impeller at OEM diameter, IJSBA

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

This page is IJSBA only, and the bodies do not agree. The same part under IHRA. 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.

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 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

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.

Legal, with conditions 4 classes

Permitted, subject to the limits IJSBA applies to every class, namely the sound ceiling, the hull repair tolerance, and the intake grate and sponson dimensions.

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

Legal, with conditions 3 classes

Modified or aftermarket impeller retaining ORIGINAL DIAMETER.

• Runabout Rec Lites · RRL.6.1
• Ski Stock · SSK.6.1
• Runabout Stock · RAS.10.1

Legal, with conditions 1 class

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

• Ski Modified

Legal 11 classes

The impeller may be modified or aftermarket, and the clause sets no diameter limit.

• Vintage Ski Limited · VSKL.6.1
• Sport Spec · section headings, no numbered rules
• Runabout Limited · RAL.9.1
• Vintage SC · VSC.6.1
• Vintage X2 · VX2.6.1
• Runabout Superstock · RSS.10.1
• Vintage Ski · VSK.6.1
• Freestyle · FREST.6.1
• Ski Grand Prix · SKGP.10.1
• Sport GP · SPGP.10.1
• Runabout Open / GP · ROP.9.1

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 · checks on parts the shop sells · how this site reads a rulebook.