Not legal 1 class
Naturally aspirated four-stroke class.
- Runabout Rec Lites · RRL
IJSBA · Forced induction
Aftermarket turbocharger or supercharger, IJSBA
Where allowed, the water-jacketed housing requirement is absolute.
Where it stands, class by class
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.
What each answer below means
- Not legal
- This comes off. The rules refuse it in this class.
- OEM part required
- This comes off. Only the part the manufacturer fitted is allowed here.
- 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.
- The rules do not say
- Unanswered. The rules do not settle this, so ask the club before you rely on it.
- 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.
Not legal 1 class
ONLY OEM HOMOLOGATED NATURALLY ASPIRATED FOUR STROKE ENGINES ARE ALLOWED.
- Ski Modified · SKM
OEM part required 1 class
RNA.5.1 is a no-modification freeze rule, NOT an eligibility ban.
OEM part required 1 class
Factory forced induction only, and frozen: no modification to any part of the system. · RAS.9.1
OEM part required 1 class
RAL.5.1 keeps the turbocharger or supercharger impeller housing stock as furnished, so the unit itself stays OEM. Every internal part, the pulleys, tensioners and intercoolers may be modified or aftermarket, with a spacer for a larger impeller where nothing else must change, which makes it a modified OEM unit rather than an aftermarket one. · RAL.5.1
Not permitted, not listed in the rules 3 classes
No clause allows a turbocharger or supercharger, changes not listed are not permitted, and the intake rule bars any change to the airflow downstream of the airflow sensor.
- Fixed Steering Ski Stock · FSSK.1.1, FSSK.4.1
- Ski Stock · SSK.1.1, SSK.4.1
- Four Stroke Ski Lites · FSKL.1.1, FSKL.4.1
The rules do not say 1 class
No forced-induction section located in SKSS.
- Ski Superstock · SKSS
Legal, with conditions 1 class
Four-stroke forced induction up to 950cc. No boost cap recoverable.
- Freestyle · FREST
Legal, with conditions 1 class
Allowed on engines up to 1100cc. Boost relief valve required. Turbo housing must be full circulating water-jacket type whenever the engine runs. The boost figures in SKGP.9.3 contradict each other, so none is quoted here.
- Ski Grand Prix · SKGP
Legal, with conditions 1 class
Four-stroke 1100cc or less only. Boost relief valve set to release above 12.00 PSI, +/-1 PSI tolerance, never above 13.00 PSI. · SPGP.9.1
Legal 1 class
Aftermarket units allowed AND may be retrofitted to an originally naturally aspirated craft. · RSS.6.1
Legal 1 class
Fully open. · ROP.8.1
Aftermarket turbocharger or 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 IJSBA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.
Forced induction · four stroke · legal in 5 of 14 answered, 3 with conditions