Currently, there are many exhaust systems available for our Project Shark Attack's '79 Corvette, from bone stock replacements to off-road-only systems. The real trick to adding a new exhaust to a Corvette is defining what system will be correct for the application and your personal sound preferences. Keeping the sound levels to a low roar at full throttle and limiting exhaust system restrictions was our overall target. We needed to consider the complete system from the cylinder heads to the rear of the car before ordering the first piece. We wanted to know the engine was running, but long road trips with loud straight pipes just won't cut it anymore. After thirty minutes or so, most Corvettes with a loud exhaust become almost unbearable. We also wanted better airflow than the stock manifolds would provide so we began to consider header options. The header choice would also determine what exhaust system was feasible.
Another major consideration was the fact that Project Shark Attack had a catalytic converter. We wanted to install new high-performance cats to keep the air we breathe cleaner. A key factor was the heat generated by the catalytic converters. We wanted to keep them from underneath the floorpan if possible. The only other location to place catalytic converters is between the exhaust down pipe and the firewall. We now know that locating the catalytic converter close to the heat source (engine) activates them faster, and they start cleaning up the exhaust quicker. If we could place the converters closer to the engine, we could also get them out from under the floor area. The only problem with this solution is that our header choice was limited.
Upon further research, we found Hooker Super Competition's Equal length header 131/44-inch primary tubes would tune our 383's exhaust flow and add horsepower if we had the area to work it all in. The unfortunate side of this option was that the long primary tubes on these headers left no room for the cats. After further thought, we realized we really didn't need them since we wouldn't be running the engine at maximum rpm most of the time, especially with the high prices for fuel today. PSA's usage will be as a boulevard cruiser and an occasional drag strip/road course warrior. The right alternative for our job was Hooker's Street Rod-style shorty headers. These headers still feature tubes of equal length but are shorter in length. By using these pipes, we still greatly enhanced our exhaust flow and now the converters could be positioned in the engine compartment area, close to the down tubes off the headers.
We chose Random Technologies catalytic converters because of their free-flow capabilities and overall small size. This is one area where smaller is better. The catalytic converters have 211/42-inch in/out tubes and small converter bodies. This configuration allows more options when dealing with tight spaces.
To get the exhaust out the rear of the car, we choose Corvette Central's complete C3 system with Magnaflow mufflers. Corvette Central fabricates these systems in-house excluding the Magnaflow mufflers. If you prefer, they can also produce OE-style mufflers for the system. The Magnaflow mufflers Corvette Central provides are modified to fit using the OE hangers and connect to the OE-style pipes to eliminate custom fitting. Over the years, Corvette Central has produced many exhaust systems for '53-'96 Corvettes, so we knew when we ordered the system it would fit the confines of PSA without any extra work. We used 211/42-inch mandrel bent elbows from our local NAPA to connect the headers to the cats and then to the Corvette Central system.
Now that we had an exhaust system plan, the only thing left to consider was the hardware and gaskets to use. One of my complaints with using headers is the constant tightening of the header bolts to prevent gasket blow-out. Those concerns are a thing of the past now when the correct gaskets are used. Earl's Performance makes a graphite foil pressure master exhaust seal set that allows the bolts to be tightened and stay tightened. The pressure master sealing material seals uneven surfaces and won't blow-out. Reduced head fasteners allow the headers to be tightened properly and stay that way so we could feel comfortable about installing the headers.
Since the install was completed, we've driven the car quite a bit. Let me answer the frequently asked question: how do the mufflers sound? Well, frankly a little quieter than we expected. We expected them to be a little more raucous. The exhaust tone at higher rpm and engine load is still nicely noticeable without being obnoxious. When you're under power on the dragstrip, the exhaust sound says you mean business. We give the Magnaflow mufflers a thumbs-up, not too noisy, but noticeable when you've got your foot on the throttle.
|ANYONE’S PROJECT | no tools required||N|
|BEGINNER | basic tools||NN|
|EXPERIENCED | special tools||NNN|
|ACCOMPLISHED | special tools and outside help||NNNN|
|PROFESSIONALS ONLY | send this work out||NNNNN|