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PostPosted: Tue Mar 25, 2014 2:30 pm 

Joined: Fri May 31, 2013 1:20 pm
Posts: 627
Just a thought here... with 100kg total fuel limit, energy efficiency has become extremely important, and as much as possible of the 'waste' energy is now being harvested - kinetic energy from braking by ERS-K and heat energy from the exhaust by ERS-H. Even though there isn't any mechanism to recover waste vibrational kinetic energy (aka noise), surely it is in the interest of engine efficiency and performance to minimise this loss, and therefore to reduce the amount of noise.

Some quick googling I did left me more confused. Accoring to this link, approx 10dB difference from 2013 to 2014 engines is doubling the loudness (ie this year's make half the moise of last year's)
"According to the sport’s governing body FIA, the sound pressure level for the new cars is 11 decibels lower than before (134 dB compared to 145 dB)," Cox commented. "Normally in acoustics, a rule of thumb is that a 10 decibel change sounds likes a halving of loudness. (

According to this other link, dB scale is log to base 10, so 10dB difference means 10 times the loudness: (

per the second site, 140dB is equivalent to 100W/m2, 145dB = 316W/m2, 134dB = 25.1W/m2. Difference is 290.9W/m2.

Noise is emanating from a car in all different directions (not exactly from a point source, but I'll take that as an approximation). What isn't clear to me is at what distance the car volume measurement from the FIA is. If measured at 1 metre distance, the surface of a sphere of 1m radius around the engine is 4*pi*r = approx 12.56m2. Multiply by 290.9W/m2 is 3655W, which is just a shade les than 5hp.

Firstly, I would very much welcome anyone with more maths / physics chops than me to either confirm or (possibly more likely) take apart my calculations.

Then IF my calculations are in the approximate ballpark, that means engine manufacturers would lose 5hp if they tuned this year's engines to match the volume of last years. Might not sound a lot but it's a huge difference when they are pushing for every hp you can get... and it explains why engines won't get any louder unless FIA mandates it.

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