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Originally Posted by patrickt
An aluminum bell, with exactly the same cavity size as a larger iron bell, will sound completely different even when struck with the same hammer using exactly the same force.
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That is correct. The natural frequency of an oscillating system is the squareroot of the stiffness divided by the mass, it works this way both for a bell and an engine block.
However if I followed your logic that the mass difference between the blocks makes a difference you can hear I must have given my small block car a deeper exhaust tone by eliminating rubber engine mounts and bolting the engine and transmission directly to the frame. This effectively increases the mass of the oscillating system by a huge amount (engine+transmission before, engine+trans+frame after).
Also what would happen to your car if you installed one of these aluminum toploaders? Would the decreased mass make it sound like a small block
Quote:
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Otherwise, a small block aluminum 427CID engine with the same compression ratio, horsepower, and timing events would send out exactly the same vibrations as an iron block FE
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I'd tend to say in that case the aluminum engine block would emit even more sound energy, as cast iron has much better damping capabilities. However compared to the sound coming from the tailpipe the difference in mechanical vibration of the block was absoltely negligible.
You sure?
