Vintage cars present a number of challenges where exhaust is concerned.
Old cars are wonderfully emotive things, but are generally far from perfect where engineering is concerned. Although you could say the same about most any car of any vintage, the fact is that the restrictive exhaust systems and obsolete muffler designs of yore haven’t improved any with age. Modern technology and engineering solutions give you the option of maintaining your car’s old-school flavor with a boost in power, fuel efficiency and sound control.
Replace the Pipes
Unless you own a musclecar era performance machine, odds are your factory exhaust system is a bit to restrictive. Even if you opt to stay with your factory exhaust size for restoration purposes, you should have an entirely new exhaust system built using mandrel-bent pipe. Mandrel bending produces a smooth exhaust system without the kinks and bend-wrinkles that mar older designs. Mandrel bent pipes will enhance flow without changing the exhaust note.
Use Thick Pipes
Older engines as a whole aren’t known for their smooth and mellifluous exhaust note, and anything but a large V8 is almost certain to produce a racket of high-frequency sound waves. Many modern exhaust shops like to use thinner-wall tubing to save weight and money; this tubing is fine if your engine produces a smooth exhaust note, but may result in irritating exhaust drone when used on vintage cars. If you take your antique ride to an exhaust shop, make sure to specify that you want the thickest-wall tubing they have.
Use a Resonator
A resonator is a small muffler that sits in your exhaust system somewhere between the engine and rear axle, and serves to catch high frequency sound waves before they can make it to the main muffler. you don’t need to buy a purpose-built resonator, either; a “cherry bomb” style straight through glass-pack installed within two to three feet of your header collector or exhaust manifold will serve the purpose. Just make sure to get one about 3/4 of an inch larger in diameter than your pipes and use adapters to install it. Otherwise, you risk impeding flow with a too-small resonator.
Use Chambered Mufflers
It’s a fact: all old cars sound cooler with all-metal chambered mufflers than fiberglass-packed units. From V16 Cadillacs to inline-3 Volvos, a chambered muffler will give your exhaust a raw, primal note which will leave no doubt that you’re running vintage iron. The only problem with chambered mufflers is that they tend to drone or sound a little ragged when used with anything smaller than a modest-sized V8. Consider a resonator of some sort mandatory if you’re running a small V8 or any six or four cylinder.