Piping Hot - The Exhaust System on Your Hot Rod
The exhaust system on your hot rod aids the smooth flow of spent gases out of an engine and reduces noise. There are three ways to muffle engine sounds: 1) Restricting the flow of exhaust gas, which results in a really quiet exhaust, but chokes off engine power; 2) Reflecting noise by splitting the flow path of exhaust gases within the muffler and using wave-cancellation techniques to create a pressure drop that reduces sound pressure and noise level at the muffler’s exit and 3) Absorbing noise. Glass-pack mufflers with one straight tube inside another absorb sound. The inner tube is perforated with louvers. Between the tubes is packing—usually fiberglass—that absorbs sound.
The first custom exhaust systems were designed for the Ford flathead V-8. Bell Auto Parts—an early speed equipment catalogers—featured Douglass Dual Tone mufflers “designed to give a minimum of back pressure with a very pleasant tone.” They cost $25 for ’49 Fords and Mercs and $23 for earlier FoMoCo cars. Also listed in the 1949 catalog were Belond headers at $27.50 a pair with plain finish or $42.50 with chrome. Clarke was another supplier listed.
The early manufacturers didn’t think about tuned-length headers, different materials (other than thin wall tubing), collector boxes or varying the number of tubes in a header. Drag racing fostered performance mufflers and exhaust pipes. Hot rodders learned that headers relied on exhaust gases to improve induction efficiency. In the ‘50s, overhead valve V-8s became the hot ticket for rodders.
The overhead valve V-8 engines and growth of drag racing in the ‘60s led to a boom in header interest, which increased further when factory muscle cars arrived. Performance type factory-supplied cast iron manifolds were new. But, the tube headers of the day tended to flex a lot as they expanded and contracted, causing small cracks around welds. Today you’ll find mild steel and stainless steel tube headers that never crack due to improved metallurgy and technology.
There were differences between early competition headers and street headers. The former often included a collector box and collector block-off plate. Street headers had to comply with a wide variety of regulations and noise codes.
One thing that hasn’t changed from the old days is the fact that the wrong headers—no matter how good they look—can make a hot rod run slower. Since a hot rod’s engine is basically an air pump, headers have to be “tuned” to a motor’s induction system to make the pump function right. If the carb is set too lean, the headers will try to collect more spent gases than the cold air intake system provides. The engine will start to gasp or choke. When headers are properly tuned for a specific engine, power gains up to 40 percent are possible.
In good headers the tubing’s shape and diameter has to match the size and shape of the cylinder head openings. You can’t bolt a 3-in. diameter tube to a larger or smaller opening and expect a smooth flow of spent gases. Likewise, you can’t bolt a round tube to a D-shaped port and get good performance or sound. This is important to know when fabricating homemade exhaust systems.
Header pioneer Gary Hooker insisted that no single exhaust system combination was right for every application. He found that Chrysler wedge and Hemi V-8s ran best with a 12-in. long x 3-in. diameter collector behind a six-in. transition pipe. However, smaller-displacement Mopar V-8s worked better with a 12-in. x 2.5-in collector. He also found that four-tube headers worked best with perfectly tuned engines, but Tri-Y designs were best for other engines.
Through racing, experiments, feedback and tests, early manufacturers like Hooker, Doug Thorley, Ed Iskendarian, Jardine, Clifford, Cyclone, Mickey Thompson and Howard Douglass learned about headers. Douglass, for instance, discovered that any time an equal-length header design was developed, he had underhood clearance issues. His answer was to use special programmed mandrel tubing benders to get compound curves of extremely short radius.
Hot Rod exhaust systems have come a long way since the days when every new design was an experiment. However, some manufacturers are returning to early designs because nostalgic “old school” hot rods are trendy today. Speedway Motors re-introduced Fenton flathead and Tru-Ram Y-block headers.
There is a growing trend—especially among West Coast builders—to create rods with vintage engines. Egge Machine sells vintage parts. Product manager Neil Matranga believes such engines are “cool at car shows.” He says building a vintage motor requires exhaust parts with the right look and sound. Egge sells split manifolds for Chevy and GMC sixes, Fenton cast iron headers for flathead Fords, Smithy’s, glasspacks, tips, dump tubes and lake pipes.
Clark and Teresa Babler today remake Porter Mufflers, developed by the Porter Brothers, of Los Angeles, in 1931. Clark handcrafts them from 14-gauge tubing with 12-gauge end caps. They have coil spring cores and stainless steel packing. Porter Mufflers come in a ceramic blue color or stainless steel.
Hedman Hedders has new Tight Tube headers available for Chevy 348/409 V-8s with 1-5/8-in. tubes and a 2.5-in. collector. In addition to standard chrome-metallic finish, the BBC headers are available with an HTC thermal coating that won’t “blue” like chrome does. Chevy 348/409 builders can also opt for Hedman’s Lakes Style Weld Up kit complete with all hardware, flanges and gaskets.
Speedway sells everything from small-block Ford classic roadster headers to straight-thru mufflers, exhaust tips and lakes pipes. Speedway’s catalog has pages filled with hardware like cut-out hook-up kits, header flange plates, copper exhaust gaskets, hi-heat coatings, manifold dressings and exhaust wraps.
Edelbrock exhaust products include accessories, Block-Hugger headers, tips, LS retro-fit kits, mufflers, shorties and Tubular Exhaust System headers. Edelbrock offers shorty headers for 1958-1964 Chevy 348/409 big blocks and systems for the 1983-1988 Monte Carlos and El Caminos catching on today.
Not all exhaust system suppliers are big mail order houses. Patrick’s Antique Cars & Trucks is a place where enthusiasts get Flathead ’32-’53 Ford/Mercury Catalog offers Mellow-Tone mufflers and cast iron Fenton headers, as well as steel tube headers for F-1 pickups. A second catalog aimed at ‘’37-’62 Chevrolet/GMC 6-Cyl.Trucks includes Fenton headers for the “Stovebolt” six.
Doug Thorley was a pioneer header manufacturer and Doug’s Headers is now part of Petronix Performance. The company markets a wide range of headers for 1964-1973 Mustangs, street rods with 354- or 394-cid Hemis and 1968-1974 AMC Javelin/AMX cars with 1-7/8-in. diameter exhausts.
Hooker is part of the Holley family and offers exciting products like its Super Competition engine swap headers for retro fitting a new 5.7-liter Hemi into 1968-1974 B-body and 1970-1974 E-body Mopars. The headers fit most manual and automatic Mopar trannies and use motor mounts that keep the tranny in its original location. All hardware and gaskets are included. Baked-on heat-resistant black paint and Metallic Ceramic Thermal Barrier Coating finishes are available.
Red's Headers makes headers for Fords from Model A four bangers to flathead and Y-block V-8s. They replace the stock exhaust manifolds and up performance over dual exhausts on stock manifolds. The headers reduce backpressure and make old time sounds. They are built in small batches from Red’s own jigs and patterns. Red says, “There’s no shortcut or "fits-all" solution to installing Ford headers, so we painstaking pattern to insure a good bolt-on fit.”
Ray T. Flugger founded Flowmaster in 1983 and the company‘s exhaust applications range from the late-model Chrysler 300 to a 1959-1964 Chevy kit. Perfectly suited to street rods and show cars. The “Flowmaster Magic” design with stainless steel internals and Cool Shell technology controls heat and sound.
Hooker Headers (Holley Tech Service)
Patrick’s Antique Cars & Trucks
Porter Mufflers Manufacturing, Inc.
HR Exhaust 01 Hedmann Rds Zoomie
Hedman’s “Roadster Zommie” headers are available for small-block and big-block V-8s..
HR Exhaust 02 Egge Flathead (not pictured)
Egge’s flathead Ford exhaust manifold works perfectly with the company’s Offy aluminum head for 1939-1948 Ford V-8s.
HR Exhaust 03 Speedway
Speedway Motors stocks a many hot rod exhaust systems including repopped Fenton mufflers like those that “Speedy” Bill Smith sold way back when.
HR Exhaust 04 Edelbrock
Shorty headers from Edelbrock fit the 1958-1964 Biscayne, Bel Air or Impala with 348- or 409-cid V-8s.
HR Exhaust 05 Porter (not pictured)
Based on a 1931 design, the Porter muffler offers stainless steel or Ceramic Blue finish and is gaining a following.
HR Exhaust 06 Patrick’s (not pictured)
Fenton cast iron headers and Fenton dual intake manifold look cool on a six-cylinder truck engine built by Patrick’s.
HR Exhaust 07 Hookers
Today’s rod builders like the Chevy LS1 V-8 and Hooker’s headers for this motor come in a complete set with all the gaskets and hardware