DIY Muffler

Written by natasha parks
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DIY Muffler
DIY mufflers are less expensive than high performance, branded versions. (Jupiterimages/ Images)

Using quality tools and supplies any car enthusiast can build a muffler that is both functional and stylish. Find out what a muffler should look like and the function the muffler should perform before constructing your own. A muffler can reduce, increase or modify the sound coming from a car engine, but it can also improve the power of the car. To create any muffler, you need to form a basic tubular shape from perforated metal, which is dampened with steel wool.

Skill level:
Moderately Challenging

Things you need

  • Perforated sheet metal
  • Bench vice
  • Mallet
  • Tape measure
  • Ordinary sheet metal
  • Protractor
  • Welder
  • Protective clothing
  • Gloves
  • Visor
  • Coarse stainless steel wool No. 3
  • Paper tape
  • Medium stainless steel wool No. 1
  • Steel tube
  • Small metal end plates

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  1. 1

    Secure a 20-inch length of 1-millimeter thick perforated metal sheeting in a bench vice. Bend it into a smooth tube using a mallet and your hands. Aim to create an internal diameter of around 2.5-inches for a 4-cylinder car, as described by Custom Car. Measure the diameter as you work using a tape measure.

  2. 2

    Make two tubular end pieces, 1-inch in length, from the same type of metal but with a smaller internal diameter, such as 1-inch, and without perforations. Bend and shape the metal ends in the same way as the main tube was shaped, using a mallet and bench vice.

  3. 3

    Position both end pieces at a 7-degree angle to the main tube using a protractor. Make the end pieces point in opposite directions to one another. Aim for an S-shape in your muffler by positioning the end pieces at an angle but keep the main tube straight.

  4. 4

    Weld the two end pieces to the two opposite ends of the main tube using a welder. Wear protective clothing, gloves and a visor during the welding process. Create an even, strong seal between the joints. Turn off the welder. Allow the muffler to cool for about an hour before continuing.

  5. 5

    Wrap course stainless steel wool No. 3 around the main tube. Create a layer of around an inch in total thickness. Apply a second layer. Use around 10 pads of wool in total to create two, well-meshed layers which will prevent overheating. According to Wold Stainless, steel wool retains its oxidation resistant properties at high gas temperatures is easily manipulated and durable but maintains cost effectiveness.

  6. 6

    Wrap the course wool with paper tape. Wrap over the paper tape with medium stainless steel wool No. 1 to a thickness of about 1-inch. Increase the thickness depending on the size of the muffler steel tubing you have.

  7. 7

    Push the wool-wrapped perforated pipe inside a 20-inch length of steel tubing. The two angled end pieces you welded into place should stick out at either end of the steel tubing. Weld the inner pipe to the edge of the outer tubing using a welder and two circular metal plates measuring 2-inches in diameter.

Tips and warnings

  • Use trial and error to fit the two layers of insulation wool and decide on the exact thickness you need as you progress. The wool expands when hot, but the paper tape burns away, so you need to balance the two.
  • Welding is harmful and can cause burns and eye injuries. Wear protective clothing and goggles at all times during operation. Do not exceed 1.5 psi of back pressure in your exhaust system according to Brake and Front End. Pressures exceeding this can result in explosion or damage to your car engine.

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