Backpressure Relief

While the exhaust on this 351 Windsor-powered ’34 Vicky looked fairly decent, the owner decided to take the system to the next level and have it recoated to freshen up its appearance. He was lucky enough to have a two-post lift in his garage, so he disassembled the exhaust system and hauled it to Specialized Performance Coating in Arlington, Texas, for ceramic coating. A few days later, he received the dreaded phone call. As soon as he heard the words, “Houston, we have a problem,” he knew he didn’t want to hear the rest of the message. It seems that aluminized pipe was not used in the system’s initial construction. Couple that with the fact that the Vicky spent much of its early life being driven infrequently on short trips, and you have a recipe for rust. In fact, the insides of the pipes looked like cholesterol-clogged arteries destined for a heart attack. Besides being congested with corrosion, the pipes were so weak that a screwdriver could poke holes in them. 

Anyone who works on street rods knows that a backup plan is usually necessary when projects are undertaken. And in this case, plan B necessitated a trip to Kinney’s Performance Exhaust Center in Bedford, Texas, for a custom exhaust fabricated by one of the best in the business, Kirk Robinson. Kirk selected MagnaFlow 2-1/2-inch U bends, mufflers and straight sections for the job. MagnaFlow components were chosen because of their outstanding quality and excellent selection, and their mufflers were selected because of their all-stainless construction, exceptional tonal properties and lack of resonance in the cabin. ROL universal heavy-duty hangers were used because they have long service life and are designed to eliminate vibration. Nothing is worse than a hot rod exhaust that subjects the car’s occupants to an obnoxious drone at cruising speed. After consultation with Kirk Robinson, it was decided that a 2-1/2-inch system without a crossover would work well. Although the Vicky’s engine was a healthy Ford Racing GT-40 prepped item, the 2-1/2-inch pipe size would afford plenty of breathing without a crossover connection between the two sides of the system. Besides, the owner had indicated a preference for the hot rod rumble that a split system delivers and did not want it diminished by a crossover.  

Kinney’s has the ability to build an exhaust system using compression bends, but this type of bend creates wrinkles in the tubing at the midpoint of the bend. The wrinkles are somewhat unattractive, interfere with exhaust flow and limit flexibility in fitment, so both appearance and performance considerations led to the decision to construct a mandrel-bent system. As the photos show, an all-stainless, mandrel-bent system made from U-bends and pipe is a lot of work. 

Once the decisions were made and materials were obtained, the cutting, fitting, welding and grinding processes began. Each side of the system required 15 welds, which were then ground smooth to give the appearance of a continuous piece of tubing without the wrinkles displayed by a compression-bent system. Stainless steel wire was used in the welder so that the system could be polished if desired. Sections were cut, test-fitted, often re-cut, tack-welded, test-fitted again and final-welded before being ground to a smooth surface. Construction of a quality system of this level takes a great deal of time and effort, but the finished appearance was well worth it. Plus, an all-stainless steel system that is ceramic-coated inside and out will probably outlast the car to which it is attached, so the effort and expense will never have to be repeated. So if you think that one exhaust system is just like another, follow along to see the work that went into creating this system. It’s definitely a work of art!