This is a step-by-step guide on fitting Astra GSi bonnet vents on to a Nova. But these can easily be fitted to other models in the Vauxhall range. These vents are the original Vauxhall items which are functional, so they are not stuck on, you will need to cut a hole in the bonnet for them to fit.

These vents were intended for the Astra GSi bonnets which have a recess in the bonnet for these items to fit flush. You won't have this option with other models so you will have to fix them on top of the bonnet. If you have the time or the money, you can fill these in so that they appear smooth on the bonnet, which has been done many a time. But with a bit of preparation, these vents will not look out of place when fixed on top of the bonnet. These vents work by the hot air being sucked out of the engine bay when the car is moving, rather than ramming cold air down with other types of bonnet vents.

"So what do I need?" you ask. First you need to buy the two bonnet vents and 6 star clips from your Vauxhall dealer or a scrappy. Those are the major parts, next you will need a jig saw, file, sand paper/wet and dry, rust stopper solution, drill and big diameter drill bit, some paint, primmer, tape measure, masking tape, pencil, sealant and some guts to start cutting your bonnet :) It isn't a very difficult job, it can be done in a weekend including the spraying...if you know what your doing.

Just before you start, make sure you note the following:

• You'll probably have to order the Astra GSi bonnet vents and star clips from your dealer, you may have to order a bag of 10 clips rather than 6, as that is usually the minimum order. You can buy the vents from a scrappy or get fibreglass copies, but I found that there is very little in money to be saved either way.
• Before finally putting the Astra GSi bonnet vents on the car, it is ideal to bend the corner on the wide end because this tends to give the impression it sticks up when fitted to the bonnet. In fact the Nova bonnet sweeps down, hence at an angle, and the vent is still straight and flat. You'll have to put something heavy on the corner over a few nights for the vent to hold to the new shape. Either that or use stronger adhesive when fitting the vent.
• The pencil that was used to mark on the bonnet was off one of those dry wipe boards that you get in the kitchen, seems waxy. This is ideal because you can freely draw on the paintwork, and it will easily wipe off leaving no marks :)
• Always cut smaller first, as you can always make the hole wider, not the other way round. Always check and check again your measurements before you cut.
• Always use a rust stopper solution on ANY fresh cuts, before it oxidises too much. Otherwise rust will set in, especially on a bonnet as it is open to the elements.
• Spraying the air vents. You can get a local paint shop to do this, but as it is a small item, it is very easy to do yourself. To any good spray job, preparation is the key and don't rush. You also need a dry warm day and an area that is free from flowing dust and dirt. First lightly rub the vents over with 400 grit paper and water. Then clean the surface of the vents of grease and dirt etc., I used white sprit, but make sure it evaporates before you start spraying (otherwise the paint begins to 'blister'). Once it is clean, start spraying your first coat of primmer. Use thin layers. Do about 3 or 4 coats. The surface may appear rough, don't worry, just lightly rub it down with 400 grit and water to make it smooth. Once the primmer is done, spray it with your car colour, again using thin layers. Do about 3 or 4 coats. It may again appear to fell rough on the surface, but this time lightly rub it down with 800 or 1000 grit paper with water. That WILL get it nice and smooth (note 100 = rough, 1000 = fine).

OK, got all the above? Then follow the steps below (remember to click on the pics for a bigger view):

Make a simple A4 template out of a corn flakes packet, as this will make life simpler when making out the dimensions on the bonnet.

With the template, position it where you want to start cutting. Keep in mind that the webbing under the bonnet takes up a lot of room, and your restricted to where you can put the air vent. I found it best to place it 1.5" from the side and 26" down from the top of the bonnet.