The ol' Dodge was back for a rigorous day of testing (tti H-pipe versus X-pipe, DynoMax Su
Most Mopar owners love the sound of their muscular V-8's. In the past, we've dyno'd and strip-tested tti's (Tube Technologies Inc.) headers and exhaust systems for small- and big-block cars. In each test, more power was obtained by picking the appropriate size tubes. We all know the right size headers, exhaust, and free-flowing mufflers look great, sound cool, and most certainly make your car quicker, but sometimes picking the right size tubes and muffler type can be a difficult task. Factor in the ability to conceal some of the compression pop you're creating, and it can be down right daunting.
What goes in, must come out, and it comes out into tubes and mufflers that will compliment peak engine efficiency without being obnoxiously loud.
We were excited to find out tti now offers bolt-on X-pipes for our popular Mopar musclecars. Now with the choice of H or X intermediate pipes from tti, we wanted to see, feel, and hear the difference at the track. In recent years, NASCAR, drag racers, and late-model V-8 musclecars have used X-pipes with good results. We recall Dave Dudek's F.A.S.T. class, 11-second Hemi Challenger realizing gains while dyno-testing a 2 1/2-inch X-pipe against an H-pipe. We wondered if the X-pipe would be beneficial in a 3-inch diameter on our wedge-powered B-Body since it features longer intermediate tubes.
TTI's new X-pipe (on the left) was easy to swap out with tti's 7-year-old H-pipe. We were
H-pipes and X-pipes optimize the flow of the exhaust by creating a balance between the different banks in a V-configured engine. While both the H and the X add to the scavenging ability of the exhaust from the engine, the X-pipe helps those individual exhaust pulses push and pull each other through the exhaust system.
We needed to pull off this track test with ease, so we trial fitted the new/old pipes and mufflers at our home garage. The H-pipe, turbo muffs, and tailpipes were tti issued and tested over seven years ago. The old muffs and tailpipes were tough to remove and required a muffler chisel. This caused damage to the turbo muffler outlets, but not to the tailpipes. In all fairness, the H, X-pipe, and muffs would be tested without the tailpipes. Once the best combo was found, the tailpipes would be installed for a return track test for tuning and decibel reading.
The veteran strip-test mule was driven to E-Town with tools, tires, tti X-pipe, and Dynomax UltraFlo mufflers. The DynoMax Super Turbos were hangin' on the H-pipe for the ride. without tailpipes, the 90-minute ride was a bit too smelly and noisy.
Up top, the DynoMax Super Turbo muffler shows off a 20-inch long case, which gives it six
We were anxious to hit the track and try out the new X-pipe and UltraFlo's, but it takes an hour to set up the R/T for the strip-unload the trunk and passenger compartment, mount the Hoosiers, disconnect the front sway bar, adjust the QA1 shocks, and set the pinion snubber. This gives the motor awhile to cool down to race temp (about 160 degrees before each launch).
On our baseline pass with the H-pipe and turbo mufflers, the 440 propelled us to 11.15 at 121.20 mph. On warm days, we normally don't hot-lap it, but we took another time shot and slowed to 11.22 at 120.83 mph. we borrowed the sound meter from E-town and it read a quiet 93 decibels.
Next up to bat would be the DynoMax UltraFlo mufflers with their advantageous straight-through design. For good preparation, the ends of the H-pipe were coated with high-temp anti-seize during trial fitting. The turbo's easily pulled off, and the Ultra Flos slipped on. The deep breathing/exhausting wedge loved those straight-through mufflers right from the get-go. We realized the added power in the burnout box. Going down the track, newfound power was felt throughout the power band, especially at the upper rpm. This time, we ran 11.01, (it was 79 degrees at this point). The Ultra Flos managed to knock off .14-second and increased trap speed by 1.29 mph, that's a big time improvement from just a muffler swap! The price paid for the added performance was a noise reading of 100 decibels-kind of loud.