I attended the NHRA Summernationals Drag Races in Topeka Kansas, and I did some sound pressure level (decibels, dB SPL) measurements for fun. Most of us know that V8 Top Fuelers (TF) generate incredible exhaust sounds, but I wanted to make some objective measurements. We all like loud sounds, so I thought I'd share it you. I was using a Realistic (Radio Shack) Analog SPL meter, fast setting, A-weighted. I wish I had a nicer meter, but the Radio Shack works well, was affordable, and a better one would run over $300. I tried using C-weighting, but at launch, the meter was pegged beyond the meter's upper limit of 126 dB, so I set it to A-weight, which "ignores" the lower frequencies, and generates a lower reading, making these readings more valid. A-weighting is used in environmental noise testing. 120 dB is generally considered the threshold of pain in the ears, with hearing damage possible in minutes. 194 dB is the upper limit of sound pressure, beyond that is a shock wave, like an explosion, volcano or sonic boom. Sitting up in the stands near the starting line, about 75-100 feet away, I read 100 dB with two TF dragsters idling. Very nice exhaust lope, like an atomic popcorn popper. At launch, the needle jumped to 126 dB (but not pegged), and it was a wall of concussive pressure waves, shaking the grandstands enough to make your eyes blurry for a second. You feel it in your chest. Awesome. The nitromethane exhaust tastes "sweeter" than smokeless powder gun exhaust. I didn't wear earplugs though. Compared to shooting guns at ear level, the noise isn't extremely loud, but it's the fierce, continuous hammering of all 16 cylinders, and the frequencies are low enough that every exhaust pulse is felt in your body. I then went to the far-end of the track, about 800 feet down, and was about 150 feet from the track (as close as I could get). I measured 100 dB as the cars launched. There was a cool half second delay from when the exhaust flames shot out until you hear the noise. As the cars roared by, the needle hit 124 dB. It was fun to feel the wave of intense exhaust impulses approach and envelope you. I bet the measurements would be quite higher if I measured using a better C-weighted meter, probably high 130s. I'm certain the starting line crew is feeling 140+ dB noises. If I had to compare a gun to a TF engine, I'd say each exhaust pipe is like a 12 gauge shotgun, firing numerous rounds in sequence. Basically, each exhaust pulse is like a 12 gauge firing, with a lower frequency, and more air volume being expelled (hmm, possibly closer to a 50 BMG). Compared to a fighter jet, think a pair of TF dragsters is close or equal to an F-15 or F-18 on full afterburner. The jet has a lower frequency, but is not as concussive. But I haven't been able to measure an F-15 / F-18 at full throttle up-close. Maybe some Navy or Air Force guys could chime in (especially the guys who got to fire the engines in the hush houses, or the carrier deck crews). A B-1 Bomber with four, 30,000 pound thrust, 5-foot diameter afterburning engines beats all of them though, in terms of thunder. I watched a B-1 take off before, cold morning, full burner, from half a mile away, and it was louder than being at the track. I've heard that special-built competition car stereos have been measured at 180 dB, which is incredible, considering the noise and power from an 8000 horsepower TF motor. Channel all the TF's exhausts into a single pipe, and I'm sure a TF will exceed 180 dB, if the SPL meter microphone can even survive inside the pipe. The car stereo vehicles are sealed, stiffened, and the microphones are placed at the point of maximum volume, so if the same advantage is given to the engines, I bet it would be close. If you haven't attended an NHRA drag race event, you should go to one sometime. I highly recommend going, especially if you like raw power, noise and hot rods! You'll get addicted to it. I'd wear earplugs though, if you plan to stay all day. Definitely hit the pits, take off those earplugs, and get up close when they fire up and blip the TF motors. Hold onto your drink!