IJSBA · Fuel
A sharp discriminator between Superstock and Open/GP.
This page is IJSBA only, and the bodies do not agree. The same part under IHRA and UIM. Which one applies to you is decided by whoever sanctions the race you enter.
Runabout Superstock keeps the stock throttle body even though the whole exhaust and turbo can be aftermarket. Easy to get wrong.
14 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.
OEM part required 3 classes
No throttle body change is listed, the intake rule bars any change to the airflow downstream of the airflow sensor, and every portion of the intake manifold must remain as originally equipped.
OEM part required 2 classes
No throttle body change is listed, and the intake rule bars any change to the airflow downstream of the airflow sensor.
OEM part required 1 class
Throttle bodies must remain stock. No throttle plate angle change, no housing modification, NO PHENOLIC OR ALUMINIUM SPACERS behind the throttle body. · SKM.5.2
OEM part required 1 class
Stock as supplied. No plate angle change, no housing modification, no spacers behind it. · RAL.5.3
OEM part required 1 class
Stock as supplied. No plate angle change, no housing modification. · RSS.5.3
The rules do not say 1 class
Throttle body rules are not stated separately in RAS.
Legal 4 classes
Modified or aftermarket, butterfly count up to the number of cylinders.
Legal 1 class
Modified or aftermarket; butterflies may be increased up to the cylinder count.
Aftermarket or modified 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 IJSBA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.
Fuel · four stroke · legal in 5 of 14 answered