Adventures with a sound meter

[Power Wagon]

Fellow TDR member Boldt's Wagon and I did some interesting experimentation yesterday in Pasco. BW has a very fine DTT tranny setup, along with 215 injectors, BHAF, no cat, and a free flowing muffler. I have a stock filter housing w/K&N and 3 inch straightpipe.

It took precisely 120 seconds to determine that his truck has a loud exhaust drone... And our sound levels proved it. Although his club can 2nd gen truck has better isolation from outside noises, he recorded 2 to 3 db louder internal noise levels at 60 mph in direct.

Both of our trucks are auto's, both 3 inch exhaust, club cab, 3.54 gears, but his is 2nd gen 12V, mine 93 1st gen. He has about 250 HP at the rear wheel, my truck is stock. Allyn's truck is definitely quieter until the engine reaches about 1800 rpm, and that point the noise escalates until his is louder than mine. It has a "boom" or drone that never really changes pitch, but drops in level while coasting.

Boldt's Wagon's truck recorded a quite steady 80 DB while cruising 60 out of OD. My truck recorded a somewhat unsteady 78 DB over the exact same road and speed. Certain stretches of road would drop to 77, but some bumps and rough spots would bump it up to 79 or 80. We did not measure sound levels IN overdrive.

Boldt's Wagon's truck has a long straight section of pipe that runs from the downpipe to the muffler. By reading the sound meter, walking around outside the truck while running the engine at the speeds it booms the worst confirm that there is strong sound levels at the middle of the truck that are almost equal to the level of noise right at the outlet of the exhaust. On the other hand, my truck has more than 10 DB louder noise while standing 6 or so feet from the outlet of the exhaust pipe.