Jono.B Posted March 6, 2008 Report Share Posted March 6, 2008 hi all, does anyone knoe about cutting vents in bonnets, to make custom airscoops, i have an idea of how to do it, but if someone could give me and idea of what tools to use ?? (i have an angle grinder with a cutting dsc) or anything i should be careful of, it would be much appreciated. thanks again Jono Quote Link to comment Share on other sites More sharing options...
Rollaboy2608 Posted March 6, 2008 Report Share Posted March 6, 2008 obviously your measurements are the key. bonnets are rarely flat, so its best to make some preliminary markings, then I normally use string, to measure out where i want the venting. If the bottom of the vent is flat, make a template(trace out the vent.) This will make it alot easier to get the exact shape you want. Its better to cut a little less out than too much. If you don't cut enough out, you can take out more. Cut out too much, and you will be left with ugly gaps. Also be careful about cutting into the actual framework of the bonnet. Most engineers wont pass the mod if the structure of the bonnet is comprimised. Cut slow, and try to use a cold cutting disc if you can. Super thin discs are best, as they generate very little heat. Heat will strip back or damage surrounding paint. You also need to check how the vent is mounted. Some require seperate drill holes, others mount close to the edge of the original vent hole, and require large washers or the like. Ive done a few scoops on top mount intercooled cars and some evo style vents, they are all different, so think it out and sketch it first. Hope this helps. Cheers, Nathan Quote Link to comment Share on other sites More sharing options...
puzzle man Posted March 6, 2008 Report Share Posted March 6, 2008 hi all, does anyone knoe about cutting vents in bonnets, to make custom airscoops, i have an idea of how to do it, but if someone could give me and idea of what tools to use ?? (i have an angle grinder with a cutting dsc) or anything i should be careful of, it would be much appreciated. thanks again Jono this is the work on the hood... Thought I would let you guys know about my latest project I'm putting speed holes in my bonnet. These are some of the materials I've used so far, fibre glass resin, fibre glass matting, hardener to set the resin, scissors and heaps of small paint brushes. This is the sort of shape I was after but more flush looking. These are actually called NACA ducts or vents here are some of the aerodynamic advantages of these http://www.wisil.recumbents.com/wisi.....;/naca-duct.htm http://naca.larc.nasa.gov/ First off I made a mould of the shape I wanted using thin sheet metal. Once the mould was made I used aluminium foil as a base sheet which I covered in vaseline to stop the resin from sticking I also did the same to the mould. What you would normally do is put one layer of fibre glass matting and cover that in resin waiting for it to harden before putting the next layer, but because I'm impatient I put on three layers and waited for that to dry. You should do it one layer at a time and wait in between to prevent air bubbles forming and wrecking the finished product. I added 6 layers in total so I only had to do it twice. I've also added extra fibre glass around the sides which will be attached to the bonnet from the underneath, because I knew that these areas will be the ones needing the most support. At the moment I'm up to the stage of modifying the bonnet, I've cut out the area where the vent will be added and have cleaned the surrounding area in preparation. I have also shaped the outer edge of the mould to fit in the hole I've cut. The next step will be fibre glassing the vent to the bonnet from the underside and then be using a little bit of bog to fill and smooth all the areas to make a flush and clean area for the final step of painting. OK this is what i was up today i cut out the 2nd hole i grinded some paint away near the 2 holes (so the resin sticks better) i shaped the 2nd vent taped up the vents 1 because the tape holds it there 2 becasue the tape stops the resin from coming on the top side. (so it should be smooth when i take the tape off) here you can see the tape and all i do is run fiberglass matt over the tape to join the vent to the hood. and it glassed Quote Link to comment Share on other sites More sharing options...
puzzle man Posted March 6, 2008 Report Share Posted March 6, 2008 and the big hole that has to be filled. this is the hole filled I didn't really have the right kind of environment at home to finish them off anymore and basically this is the only way I have been shown how to do this kind of thing. I just figured at the time it would be easier to attach them to the bonnet and have a solid area that was bigger and more stable for me to work with. I mainly used the bog to really get the finished shape I wanted and to smooth out the area for painting. This is the first layer of bog I've sanded it back and shaped the area a bit more and will add one more layer just to even it out and smooth the area completly. looking good at last.... i primed it today and looks heaps better. this is just primer on the bits that were back to bear metal next week it will get hi-filled Got hi-fill/primer yesterday just have to leave it for a week to "bake" or dry up. then will wet rub and reddy for paint...... the hood is looking at not getting paint any time soon as hair line cracks have formed were the fiberglass joined metal... I'm glad i have left it unpainted this long or the cracks would have been on the top of the paint. To fix the problem i have to get the di-grinder out and cut it back to were metal meets fiberglass and bog it as the fine bog i will use will be flexible so in theory there should be no cracks in the long run... metal=flex fiberglass=no flex, when you close the hood it flexes a lot it might not look it but it does. so when all the hood has moved flexed the bits that can't flex with it (the fiberglass) will brake away from the stuff that can move/flex Quote Link to comment Share on other sites More sharing options...
tas_ae71 Posted March 7, 2008 Report Share Posted March 7, 2008 another option which i have went for is spacing the back of the bonnet up with a few thick washers and some longer bolts. surposed to help with cooling and add to the overall theame of my car. it also isnt permanant so if you don't like it then you take the washers out or add them to get the look you want. Quote Link to comment Share on other sites More sharing options...
Rollaboy2608 Posted March 7, 2008 Report Share Posted March 7, 2008 that is a good point tas, seems to be popular with the jap racing/drifting scene, and looks kinda racy, although I'm not sure how much benefit you'd actually gain from it, cos really you're letting some hot air escape, but not replacing t with cool air, so maybe in conjuction with a scoop, this could be effective Quote Link to comment Share on other sites More sharing options...
WinKE55 Posted March 7, 2008 Report Share Posted March 7, 2008 It looks good. Though I prefer the middle, two nose looking ones.. I don't know what they are called. Though they go on some Crysley.. PT Cruiser or whatever it is. Quote Link to comment Share on other sites More sharing options...
the Db king Posted March 7, 2008 Report Share Posted March 7, 2008 ive got a hornet scoop on the side of my ke70 panal van above the carby with the air filter sticking out of the bonnet under the scoop. Quote Link to comment Share on other sites More sharing options...
harun Posted March 7, 2008 Report Share Posted March 7, 2008 I'm sure mods to the bonnet of any sort require an engineers cert? Quote Link to comment Share on other sites More sharing options...
the Db king Posted March 7, 2008 Report Share Posted March 7, 2008 as long as the structure under the bonet isnt cut and it is with in legal height its fine Quote Link to comment Share on other sites More sharing options...
Jono.B Posted March 8, 2008 Author Report Share Posted March 8, 2008 ive got a hornet scoop on the side of my ke70 panal van above the carby with the air filter sticking out of the bonnet under the scoop. yeah man thats what I'm wanting to do, or mount some kinda scoop on the carby that will pop out of the hood... does it make much of a difference to it or not really?? .. like heat and performance wise Quote Link to comment Share on other sites More sharing options...
the Db king Posted March 8, 2008 Report Share Posted March 8, 2008 (edited) didn't find a temperature drop but the intake note from the 32\36 webber is LOUDER and it does benifit performance wise on a cold morning or nite, (like any form of cold air intake) Edited March 18, 2008 by the Db king Quote Link to comment Share on other sites More sharing options...
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