civicminded wrote:
Would be curious to see your LRP exhaust. I'm sure Richie, myself and a few of my buddies, would appreciate some input. I've tried turn downs, drivers' side exit(away from the meter), and an assortment of mufflers, but 9000 rpms' in a Honda is hard to muffle. The muffler would also need to be around 4" as I wouldn't have clearance to load on the trailer.
The conversations about exhaust are always interesting to me. Sound regulations are real, and growing at any number of tracks, so the prudent racer needs to find a solution. I've seen any number of interim solutions that did the job, just barely, and always the complaint is that it "costs horsepower." The solutions are out there - they just take work (and sadly) some expense. On our 650 HP Trans-Am car we hit upon a solution that struggled to blow 91 dB on a damp day using exhaust bits from Burns. By the way, according to the dyno, that package cost us no power. On my rotary I used a Mazdaspeed package combined with a simple turndown.
Some tricks and observations based upon experience:
1. Supertrapps don't work.
2. Walker makes some wonderful stuff at reasonable prices. Get the biggest one you can fit, or two slightly smaller ones if that works better, such as on Civics.
3. Burns is the schnizzle, and charges accordingly.
4. Often a turn-down mounted under the car and pointed at the ground works, but a sound engineer friend says just the opposite can happen - the sound/pressure wave echoes off the ground, back into the car, and that big body acts like an amplifier, making things worse. Experimentation is key. Radio Shack sells a decent dB meter for reasonable money. Buy one and know for sure.
5. Don't settle for "close enough." Weather can affect things - sound carries more in damp conditions than in dry. State of tune can change things as well. Case in point - a few years ago we had a collection of Spec Miatae get in trouble for sound at LRP. These were all cars that had raced there all year long with no problems, but suddenly were killing the meter. The problem turned out to be timing. It was a cool day, they were running more static lead to take advantage of the cooler weather, and on decel they were spiking the meter - a component of the engine sound was awful. Once they figured out that taking 1 or 2 degrees of timing out was the solution, all was well in the world.