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Over the last couple of issues, we took a close, hard look at high tech mufflers and exhaust system components. To recap, the first part of the series looked at two different muffler styles (in three different cases). There’s a lot of info in that segment, but perhaps the most important takeaway from the first part of this series was the fact one doesn’t really have to trade exhaust flow and lose a lot of power from mufflers. In the second segment we examined the benefits of cross overs. We also shared some first-hand info with regard to the use of a cross over system fitted to a dedicated NHRA drag car. That well sorted racecar didn’t pick up much from the cross over, but it still proved to be interesting! The moral there was, never under estimate the power of sound. If you just joined us, point your browser back to those first two articles.
This time around, we’ll look at a great (complete) system offered by Hooker Headers, and we’ll also dig into the differences in exhaust system materials. We’ll provide a little insight into exhaust system materials: Not all systems are created equal and you really do get what you pay for (likely no secret to anyone reading this!). Check it out:
The Hooker Headers system shown in the accompanying photos (Hooker part number 70501321-RHKR) is a 3.00-inch diameter job for a 1968-74 Chevy Nova. This system is engineered with a high-efficiency stamped x-style crossover along with high-flow TIG-welded 304 stainless steel absorption VR series mufflers. The system incorporates factory quality hardware (including clamps, hanger rods and rubber isolators). As Hooker Headers points out, this ensures great fit and a leak free installation. It also clears the stock park brake cables and includes tail pipe turndowns that exit under the rear quarter panels (this is a stock Nova style exit).
Before going any further, let’s stop for a bit and ponder the different types of steel used in an exhaust system. The most common (and least costly) is mild steel. Without protection (such as an exhaust system coating), it will be prone to rust through in short order for a daily driver. Depending upon where you live, you can expect to replace mild steel components in as little as 2-3 years. Next up is aluminized steel. Aluminized steel is actually mild steel that has been hot-dip coated on both sides with aluminum-silicon alloy. The way it is dipped ensures there is a tight bond between the steel and the aluminum coating. It has relatively good corrosion resistance and is a bit more costly than mild steel. Depending up your location and how much you use the car, it can have a life span as short as 3-5 years.
Next up is 409 stainless steel. It is more expensive than aluminized steel and has good corrosion resistance, but it will show rust in daily use. The reason is that 409 stainless actually has quite a high iron content. A magnet will stick to 409 stainless. Expect it to last 8-10 years (again, dependent upon use and, of course, the locale).
Finally, there’s 304 stainless steel. It is classified as an “austenitic stainless steel” and has a much higher percentage of chromium and nickel in its content compared to 409 stainless. It will not rust, but will eventually discolor from heat (gaining a golden hue). Some areas of a 304 stainless exhaust may prove magnetic, but that’s usually where it has been bent or welded. 304 stainless is the most costly of the common exhaust materials, but a system built from this steel can easily last 10+ years (though again, this is very much dependent upon location and driving conditions).
When it comes to clearance - particularly in the case of the driveshaft, since it does tend to hug the floor of the car closely - Hooker has this to offer on the system shown in the accompanying photos (designed for a LS Nova swap – 1968-72): “The Hooker 70501320-RHKR 2.5” exhaust system is compatible with drive shafts up to 4” in diameter as received. The Hooker 70501321-RHKR 3” exhaust system is compatible with drive shafts up to 3.5” in diameter as received and can be made to be compatible with a 4” diameter driveshaft on most cars by modifying or dimpling the passenger side outlet leg of the X-pipe assembly.”
FYI, Hooker Headers offers similar full “Blackheart” systems for a wide range of vehicles. Examples include first, second, third, fourth, fifth and sixth generation Camaros, Corvettes, Chevelles, Novas, G-bodies, C-10 pickups, Firebirds, Cadillacs, Ford Mustangs and more. Most are true dual systems (even on third and fourth Gen F bodies). All are manufactured with 304 stainless steel.
We’re not quite done with our “Muffled Mayhem” series. In the final segment, we’ll take a closer look at how the Hooker Headers system goes onto a car. It won’t be a blow-by-blow install, but we’ll lay out just how easy it is to work with this system. Watch for it!
Determining exhaust materials is pretty much impossible by way of a photo; however, Hooker Headers’ Maximum Flow muffler is based upon a 16-gauge aluminized steel case and a mix of stainless steel and high temperature fiberglass internals.
The Aero Chamber muffler from Hooker Headers is also based upon a 16-gauge aluminized case. Like the max flow, the internals are stainless steel.
VR series mufflers are based upon a 304-series stainless steel case and a mix of stainless steel and high temperature fiberglass internals.
The exhaust pipes used in the Hooker Blackheart kits are manufactured from 304-series stainless steel (the best practical choice).
409 stainless is magnetic. 304 stainless is not magnetic, but there are some caveats. See the next photo:
Where 304 stainless is bent or welded (as shown here), a magnet may occasionally stick to the material.
