CLARIFICATION OF THE REGULATIONS RELATING TO SOUND CONTROL FOR TRACK RACING CONTAINED IN THE TECHNICAL RULES CIRCULATED ON 23RD FEBRUARY 2011.
From discussions which took place at the ACU Clerk of Course Seminar at the weekend, it would appear that some confusion has arisen due to the lack of understanding of the “old” and “new” FIM Sound Control Methods. To clarify this, the “old” method refers to the ACU Static Test which has traditionally been used to test sound levels: i.e. the sound level is measured at 0.5 metres at a fixed engine speed. The “new” method refers to the FIM 2 Metre Max test which is currently being used internationally i.e. this test is conducted at 2 metres from the motorcycle, with the engine ‘blipped’ at maximum revs. This does not mean that the engine is held at full throttle for any great length of time.
The reason for the introduction of the revised systems is that as engine revs have increased, the sound levels at racing speeds have increased, and especially in classes using the modern 500cc track racing engines. The sound levels measured during the ACU Static Test bear no relation to the sound levels recorded at racing speeds.
As a result of this, local authorities are putting increasing pressure on organisers to reduce overall sound levels, and the revised silencer rules for 2011 is the response of the ACU to meet the reasonable requirements of local authorities at a minimum cost to ACU licence holders.
THE REVISED RULES ARE REPEATED BELOW.
• 500cc Solo and 500cc Sidecar Motorcycles (excluding Pre 75 and Upright classes): Must use a 2010 FIM Homologated silencer. The only exceptions are machines using engines not designed for track racing. In this situation an alternative silencer MUST be used and will be subject to sound control using the FIM 2 Metre Max method of testing.
? Note – motorcycles using a standard FIM 2010 Homologated silencer will not be tested. However should testing in this class be required (e.g. for a damaged or modified silencer), the test will be carried out using the FIM 2 Metre Max method.
• 250cc and 350cc Solo Motorcycles: Must use either a 1995 FIM OR 2010 FIM Homologated silencer. The only exceptions are machines using engines not designed for track racing where an alternative silencer MUST be used and will be subject to sound control using the ACU Static method of testing.
? Note – motorcycles using a standard FIM 1995 or 2010 Homologated silencer will not be tested. However should testing in this class be required (e.g. for a damaged or modified silencer), the test will be carried out using the ACU Static method.
? This represents little change for the 350cc machines, which have been required to use FIM Homologated Silencers in ACU events since 2007.
• Pre 75 and Upright Solo Motorcycles: Must use either a 1995 FIM OR 2010 FIM Homologated silencer. The only exceptions are machines using engines not designed for track racing where an alternative silencer MUST be used and will be subject to sound control using the ACU Static method of testing.
? Note – motorcycles using a standard FIM 1995 or 2010 Homologated silencer will not be tested. However should testing in this class be required (e.g. for a damaged or modified silencer), the test will be carried out using the ACU Static method.
• 1000cc Sidecars.
Will be subject to sound control using the FIM 2 Metre Max method.
• 200cc and Under Motorcycles.
Will be subject to sound control using the ACU Static Method.
Peter Gregory
23rd March 2011.