Here's the rusted-out and...
Here's the rusted-out and cut-away 7-year-old Dynomax Super Turbo that lead us to this test. With a 3-inch inlet/outlet and baffles, this hi-flow muffler outperforms many other turbo mufflers. The Super Turbo has two patented flow directors to channel the exhaust flow where it makes two turns inside the muffler.
Our original intentions were to test both types of mufflers on the X-pipe, but we declined after the Ultra Flo results. The collector-reducers were also previously coated with anti-seize to ease swapping the H- and X-pipe. Besides, tti's components have always proven to provide ease of installation and fit. Next, the tti modified-to-fit UltraFlos were hung in place and attached to the X.
After firing up the mule with the X-pipe, we noticed a quieter, smoother sounding exhaust note. All present commented the X-pipe produced a more pleasant tone. Remarkably, the X-pipe seemed to slightly smooth out the idle and throttle response. This was confirmed with a best, for the day, 1.56 sixty-foot time. Ironically, the quarter-mile e.t. was nearly identical to the H-pipe. At this point, the ambient temperature was up to 82 degrees. We were happy the X-pipe was helping the R/T go as fast as the H-pipe, but with a smoother idle, better throttle response, and less noise (decibels were down to 97), we couldn't go wrong.
As seen here on the E-Town...
As seen here on the E-Town tarmac, the UltraFlo is a straight-through muffler for maximum flow and power. It is built with CRF (continuous roving fiberglass) to provide better sound absorption (more area) than a glass pack, while delivering a powerful sound. Take notice, most of the F.A.S.T. (factory appearing stock tire) class racers use UltraFlo mufflers.
Satisfied with the results, we packed it in and called it a day. Many X-pipe converts will notice their engine A/F will richen up. After a plug check we didn't notice any difference. An effort towards leaner jets was an afterthought for another day. This would enable us to install the tailpipes in the comfort of our home garage.
X-Back Track
Once back to the track, we were faced with a day showing more heat and humidity along with a lower barometric pressure. To a drag racer this only means a slower car. The unfavorable air slowed the baseline a tenth to 11.11 at 121.10 mph. One of the benefits of having a complete exhaust system-the R/T was now two decibels quieter with much less interior noise.
On this sultry day (86 degrees, 73 percent humidity and 29.80 barometer), we next decided to try leaner secondary jets (from 78 to 76). We thought on this bad air day that leaner would be meaner; instead we slowed to an 11.17 at 120.62. Apparently, our wedge wanted more fuel. Would a move to 80 secondary jets help?
Parts removal and trial fitting...
Parts removal and trial fitting were done at home to prevent any hang-ups at the track. The outlet of this 7-year-old Super Turbo was shredded with a muffler chisel to save the same age tti tailpipe. All the new and used tti exhaust components fit well together. Again, hi-temp anti-seize was used on all exhaust connections and components.
Back in the pits, we upped the carb mixture on the Holley HP in a last ditch effort. Testing with worsening weather conditions, even with one-hour cool-downs, is not advantageous when considering engine heat sink. Out of the hole the 60-foot e.t was back, and the quarter e.t was only two hundredths faster. At that point we decided we would try tuning our combo on a different day with better weather conditions. We learned from testing the importance of matching tolerable exhaust tones with desirable performance gains, while finding that happy medium.
Conclusion
The X exhibited a nice, new sound, while still sounding like a rocking big-block. With three less decibels, the quieter tti X-pipe is there to stay on the R/T. Even though our combo didn't e.t. any better with the X-pipe (possibly because of less than favorable weather conditions when tested), the idle and throttle response feels smoother and stronger. The big surprise was the muffler swap; the UltraFlo's are definitely an improvement. We were impressed at how the X-pipe and Ultra Flos teamed up to give us our best 60-foot and quarter-mile e.t ever; this on a day that was thirty degrees warmer.
B-Bodies afford a lot of space...
B-Bodies afford a lot of space for hauling tires, tools, and parts. At the strip, the 30x9-15 Hoosier radial slicks and 26-inch front-runners are mounted, the front sway bar is disconnected, and the QA1 shocks and pinion snubber are adjusted to be ready to run. By removing the spare and jack, the test weight can be brought down to a portly 3,880 pounds.
We began baseline testing...
We began baseline testing with the H-pipe and Super Turbos minus the tailpipes. For the first pass of the morning (11:00 a.m.) it was 77 degrees. The H-pipe and the Turbos established an 11.15 at 121.10 mph on E-Towns scoreboard. The sound meter showed us a quiet 93 decibels with the large mufflers.
Next, the Super Turbos were...
Next, the Super Turbos were removed and the UltraFlos slipped on the H-pipe. On our routine 5-second, 5,000-rpm burnout, the decibels went up to 100. It was a bit too loud, even for this gearhead, especially if I had to drive for an extended period of time. The Ultra Flos blew away the Turbos by dropping the e.t. to an 11.01 at 122.39. That can make the extra noise worth it.
We borrowed this sound level...
We borrowed this sound level meter from E-Town Raceway Park to record the decibels from the different exhaust configurations. One of the EMTs from E-Town's ambulance crew helped us record the decibels. The noise was checked 50 feet from the side of the burnout box. we found out after the test that E-town's limit on sound-restricted days is 96 decibels at 100 feet from behind the burnout box. The R/T was well under those sound limits for all the tested exhaust configurations.
With the UltraFlos delivering...
With the UltraFlos delivering the goods, we teamed them up with the X-pipe. The X-sound has a more pleasing pitch to the ears at 97 decibels (3 less than the H-pipe). A noticeably smoother idle and improved throttle response also resulted from the X-pipe. At three degrees higher air temperature resulting in longer engine heat sink, the X-pipe still managed to produce the best 60-foot time. Ironically, 1,320-foot e.t. was the same, probably from the extra heat.