Heavier Cars Tend to Reduce Noise
Question: I purchased a new 1989 Toyota Camry and I was not aware of the noise level inside. There is no fiberglass sound-deadening material under the hood. Driving in it is like holding a sea shell to your ear. The dealer said this is all normal, but the car is 10 times noisier than my 1986 Buick Sommerset. How does one institute a recall? --P.S.W.
Answer: One person does not institute a recall, though your complaint about your new Camry is understandable. Although it may seem 10 times noisier than your Buick, it is probably no more than twice as noisy.
The reason is that your Buick probably had a V-8 engine and weighed possibly twice as much as your new Camry. As a result, the engine was far smoother, and the car was able to better absorb the noise.
Many buyers of traditional large American cars give little consideration to Japanese compact imports because of their harsh ride and their noisy engines. That’s not an indictment of Japanese cars--it’s just reality that larger American cars with bigger engines are inherently quieter.
A V-8 engine is smoother by design. On each full stroke of the eight pistons, two of them are in their power or ignition cycle at any one time. By contrast, only one piston is in its power stroke on any cycle in a four-cylinder engine. Engineers describe this as a 90-degree versus a 180-degree power impulse, based on the degrees of rotation of the crankshaft.
Some four-cylinder engines in luxury cars such as the Porsche can compensate for these natural imbalances with a device called a counter-rotating crankshaft. In all cars, the crankshaft generates noise and vibration when it converts the up-and-down motion of the pistons to circular motion that propels the cars. A counter-rotating crankshaft is a second shaft that is supposed to exactly offset the vibration created by the regular crankshaft. But even these engines are not as smooth as a good-quality V-8.
And finally, the total mass of a large American car helps tame the engine. When you have a car that weighs 3,000 or 4,000 pounds, it can better absorb the vibration and related noise of the engine than a 2,000-pound car. In addition, it is likely to contain more insulating materials than the lighter car.
The sound-deadening material on the inside of the hood, which you feel is lacking in your Camry, does little to quiet the engine for the occupants. Its main function is to help abate noise that goes outside the car. The sound going to the occupants is abated through engine mounts, the muffler system and sound insulation on the engine firewall.
If you don’t believe this explanation, you should test-drive a Camry V-6 and compare it to the Camry four-cylinder engine. It is far quieter, but still probably not as quiet as your old Buick. Your Camry is highly regarded for its quality, but unlike a lot of American cars, it isn’t particularly easy on your senses.
Q: While passing a neighborhood gas station, I noticed that it offered so-called racing gasoline rated at 100 octane. I wonder if that will provide some added punch? --M.G.
A: Even if this gasoline contains 100 octane, it will certainly add no punch to any standard production car. All car engines have octane ratings for the type of gasoline they need to burn, but no manufacturer requires a 100-octane gasoline.
Some engines degrade over time and require higher octane fuels, but 100 is out of the range for almost all engines. Finally, you have to wonder how this octane was achieved. Was it through refining or through additives? If it was additives, then it could very likely be a potent concentration of gasohol, which might not be good for your fuel system.
