1965 Olds Cutlass - Twist & Shout
With The Help Of The Roadster Shop And Hooker, We Add Some Bark To Project Olds By Bending Up A Custom Exhaust System.
From the November, 2010 issue of Popular Hot Rodding
By Stephen Kim
Photography by Robert McGaffin
The 3-inch Hooker Aero Chamber...
The 3-inch Hooker Aero Chamber mufflers used on Project Olds feature a stepped acceleration chamber and a resonance chamber to maximize scavenging while minimizing exhaust drone. Their polished stainless steel finish adds a touch of bling. The 16-gauge steel U-bends and J-bends have radii of 6 and 4 inches, respectively. Hooker offers pre-bent tubing in a variety of angles and radii.
When in Rome, do as the Romans, but when in the Midwest, do as the tundra. As soon as the soil thaws, it's time to go racing, and Wisconsin-based photo stud, Robert McGaffin, has been doing just that with his big-block-powered '65 Olds Cutlass. Even before the snowmelt had a chance to make its way back into the Mississippi River, the Cutlass has already tackled Road America's infamous high-speed sweepers and turned dozens of autocross laps. Mac says that it almost makes up for having to battle the frostbite, hypothermia, and overall misery associated with subzero photo shoots. Almost. Obviously, Project Olds hasn't been running around with an open exhaust, and in our haste to document our on-track escapades in the magazine, we've held off on covering the exhaust buildup. So while some oiling issues in Project Olds are being addressed, now's a good time to show you how we routed the fumes from the header collectors to the tailpipes.
As is sometimes the case with engine-swap applications, it proved easier to bend up a custom exhaust than to find an out-of-the-box kit compatible with our specific engine, trans, suspension, and rearend combination. Heavy-duty driveline and suspension components tend to eat up additional real estate under the car, and Project Olds' dropped stance throws a monkey wrench into the mix as well. Fortunately, with the wide array of fab components available via mail order or from you local muffler shop, all it takes to rig up a custom exhaust is welding skill and some basic know-how. For parts, we ordered up a pair of Hooker Aero Chamber 3-inch mufflers, 10 feet of straight tubing, and some 180-degree J-bends and U-bends from Hooker. A universal Flowtech X-pipe was integrated into the final assembly as well.
Manning the bandsaw and welder was Dave Eggen of The Roadster Shop. Eggen's daily duties involve fabbing up custom hardware on ultra high-end street machines, and watching a battle-tested pro transform a pile of raw parts into a tightly fitting exhaust system was very impressive. Although Eggen has more fabrication experience under his belt than most at-home builders, anyone can emulate the tips and tricks he has to offer and piece together a custom exhaust. All it takes is willpower and practice.
When plotting out the route...
When plotting out the route of an exhaust system, Eggen recommends starting at the front of the car, then moving rearward. For aesthetics, he likes to make the left and right sides of the exhaust look as symmetrical as possible. Before making any cuts, he bolted the collector extensions to the headers to check for sufficient crossmember clearance.
The X-pipe should be placed...
The X-pipe should be placed as far forward as possible, since the front of the driveshaft has the least up-and-down movement. To angle the collector extensions into the X-pipe, they were cut right after the crossmember, before being tack-welded to a 45-degree section of pipe. For the sake of simplicity, cuts should be made in increments of 15 degrees, which make it easier to keep the longer sections of pipe parallel to the framerails. Eggen says that if cuts are made at odd angles, such as at 43 or 41 degrees, then the intermediate pipe will have a tendency to point inward or outward as opposed to going straight back toward the rear bumper. When possible, 45- and 90-degree angles are ideal.
To assist in making accurate...
To assist in making accurate cuts, Eggen likes to draw a chart on the worktable, using a protractor to mark lines in 15-degree increments. The vertical lines extending upward from the X-axis help determine the radius of the cuts. Eggen then uses a U-shaped straightedge to mark the location of the cut on the pie and to ensure that the cuts are square. Without using a similar technique, he says that the openings of the pipes will not be perfectly circular, making them difficult to weld together.
For maximum ground clearance,...
For maximum ground clearance, the intermediate pipes needed to be tucked in as close to the driveshaft tunnel as possible. Eggen suggests having a minimum of 1/4 inch of clearance between the piping and any other portion of the car. The trajectory of the X-pipe, once it was welded up, pointed toward the rear tires. To correct this, Eggen welded a 45-degree bend to each side to move the piping closer to the driveshaft and farther upward for additional ground clearance.
|THE COST SO FAR
|'65 Olds Cutlass
|DSE four-link suspension
|DSE front suspension
|Baer front and rear brakes
|DSE brake booster
|DSE steering kit
|Strange S60 rearend
|SAM 461 big-block
|Hurst five-speed trans
|Custom Hooker exhaust
|WHERE THE MONEY WENT
|Hooker Aero Chamber mufflers
|3-inch tubing (10 feet)
To swing the intermediate...
To swing the intermediate pipe outward and into the muffler inlet, Eggen tacked short 45-degree sections of tubing onto both the I-pipe and muffler. Then, a piece of straight tubing was used to connect them together.
When building a custom exhaust,...
When building a custom exhaust, the fewer the bends and cuts the better. Nevertheless, aiming the X-pipe outlets straight at the mufflers-which were mocked in position on stands-required welding a second stub of pipe onto each outlet. Rotating the tubes helps fine-tune the angles needed for efficient routing, and Eggen marks the pipes with a Sharpie to gauge how much they need to be moved.
As Eggen lays out the exhaust...
As Eggen lays out the exhaust system, he holds off on completely welding everything up until moving the entire X/I-pipe assembly onto a worktable. It's much easier to break a tack weld in case you have to correct a mistake, and looking at the entire X/I-pipe on the table makes it easier to eliminate the gaps between each tube. Gaps tend to shift the exhaust pipes in different directions, and a small gap near the front of the car can result in a pipe that's off by several inches in the rear of the car. After throwing down the final welds to the X/I-pipe assembly, it was bolted in place.
Supporting the mufflers to...
Supporting the mufflers to the rear crossmember are custom stainless steel brackets. Welding to the top or bottom of the muffler case can crack it, so Eggen says it's best to attach the bracket near the weld on the muffler outlet. A rubber bushing attached to the frame side of the bracket isolates the crossmember from vibration.
The final obstacle was fabricating...
The final obstacle was fabricating the over-axle pipes. There isn't much space between the muffler outlet and the rearend, so Eggen used a 90-degree bend to turn the pipe upward sharply. From there, it hooks up with another 90-degree bend, followed by a straight pipe that runs over the axle. Next, another 90-degree bend routes the exhaust downward. Before mocking up the pipes, the rearend was jacked all the way up to ensure adequate clearance during suspension compression.
Like the muffler, the tailpipes...
Like the muffler, the tailpipes were secured to the car with custom straps. The turndowns were set at a 45-degree angle, as opposed to a 90-degree angle,
to reduce exhaust resonance.
As with the X/I-pipe, final...
As with the X/I-pipe, final welds were made to the over-axle pipe on a worktable. The tailpipes and over-axle pipe are essentially a single assembly that can be unbolted from the mufflers and removed from the car in one piece.
After clearing the rearend...
After clearing the rearend with the over-axle pipe, the exhaust was routed outward in order to position the tailpipes on the outboard side of the framerails. This required a 30-degree bend followed by a 60-degree bend to route the tailpipes upward and closer to the trunk floor.
Even with the bulky Dana 60...
Even with the bulky Dana 60 rearend, DSE coilovers, and hunkered-down stance, the custom Hooker exhaust tucks tightly beneath the car. The setup has yet to scrape on anything, and it sounds wicked.