How to Make Bonnet Vents

Written by colin rowe
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How to Make Bonnet Vents
High powered cars often come with extra vents to improve cooling. (Red supercar image by Christopher Dodge from

Car engines need cool air to work properly. This is because parts of the engine can get very hot and malfunction. In lower powered cars, the radiator and front grill were more than capable of doing this, but with more powerful cars there was a need to increase the cooling. Many manufacturers, such as Mitsubishi and Subaru, have added bonnet vents to increase the air flow to certain parts of the engine like the turbo and the intercooler. Adding these yourself is not a difficult task, but a lot of care needs to be taken so the job looks professional and improves the cars performance.

Skill level:

Things you need

  • Ankle grinder or jigsaw
  • Fine wire mesh
  • Sandpaper
  • Hood vent
  • Rivets
  • Rivet gun

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  1. 1

    Establish where the best place to put a vent would be. A lot of cars which come with bonnet vents have them in the middle to keep air running over the intercooler, while others have them in strips on each side of the bonnet to add extra cool air into the engine bay. If you have added a turbo, then place the vent above it, if not, down the sides of the bonnet will be best.

  2. 2

    Cut out the areas of the bonnet you want to using the ankle grinder or jigsaw. If you are using a bonnet vent, measure around it to see how much you need to cut. Cut from under the bonnet.

  3. 3

    Sand the edges of the hole with some sandpaper.

  4. 4

    Install the fine wire mesh over the hole and attach it using rivets and the rivet gun.

  5. 5

    Attach the bonnet vent as instructed to by the manufacturer.

Tips and warnings

  • Most cars that require extra cooling will come with vents in the bonnet. Unless you have added a turbo this may not be worth while.
  • Be neat with your work. This modification will be very obvious to passers by.

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