It has been way too quiet on the list lately, so I thought I would post this report. Yes, another muffler experiment. Seems I can't get beyond the exhaust system.
I did an experiment yesterday... with interesting results. While I am very pleased with the muffling qualities of the tangential muffler, I have been suspicious of it being responsible for the less-than-expected performance of my p-port 20b. So, I removed the tangential muffler and replaced it with the previous 3-into-1 exhaust w/DNA muffler that I had been running for about 100 hrs.
First the bad news. The 3-into-1 system is much louder, to the point that it almost overwhelms my Zulu. I haven't shattered any windows, but little children and small animals have been reported running for for their mothers. FWIW, I'm running the stock exhaust splitters that came in the 20B housings.
The positive news is that I picked up 10-12 mph on top speed! So, it confirms my suspicions that the tangential muffler is too restrictive for my engine. While definitely not optimal, the 3-into-1 design is clearly better than the tangential muffler when it comes to making power.
So, my plan is to build another exhaust from 625 inconel, making all three runners 31.5". I haven't decided what I will use for a muffler. I'll report back when I have more data.
Mark