Hey guys, I own a white 2013 Ford Focus ST. The previous generation Focus in Europe had a trim called the "RS". That trim also had hood vents/louvers. I ordered a set of the vents from eBay and received them in the mail and they're perfect. I'm just not sure how to go about actually attaching them to the hood. I'll include the link to the eBay auction below so you can get a better look at what I'm trying to explain if needed. They're fully functional vents so I know that cutting into the hood/bonnet is necessary. They come with a cut-out guide that you can tape to your hood which I'm planning on using. But once I cut the hood, how do I actually go about securing the vents? Is it best to use epoxy or something like 3M double sided tape? These will be permanent; I have no plans for them to be removed. I will be created silicon plugs that will fill up the vent so I can deal with harsh weather but the vents themselves will be permanent.

Any advice would be appreciated.


http://www.ebay.co.uk/itm/Focus-RS-MK2-style-ABS-plastic-bonnet-vents-FORD-PROFILE-universal-/171032733372?fits=Model%3AFocus%7CCars+Type%3A2.5+RS&hash=item27d25866bc:g:5sgAAOSwiLdWAuZs

2 part epoxy that can be used from plastic to metal. I believe 3m and sem make this product

I did an entire vented hood similar to those vents on my 2006 Corvette. Those look pretty nice. I am assuming its' like an undercut, then they just drop in? If that is the case you could either way with them. Epoxy would definitely hold but you are probably going to get some heat cycyling from underhood heat and sun from the outside. The 3M tape would be a more flexible buffer for that kind of movement. As far as the weather thing goes, my hood had "rain trays" on the under side with offset vents that cupped upward, then a drain near the lowest part. Motor always stayed high and dry.....

DarrelK wrote:I did an entire vented hood similar to those vents on my 2006 Corvette. Those look pretty nice. I am assuming its' like an undercut, then they just drop in? If that is the case you could either way with them. Epoxy would definitely hold but you are probably going to get some heat cycyling from underhood heat and sun from the outside. The 3M tape would be a more flexible buffer for that kind of movement. As far as the weather thing goes, my hood had "rain trays" on the under side with offset vents that cupped upward, then a drain near the lowest part. Motor always stayed high and dry.....

There's a pretty good percentage of the engine bay that won't matter if it gets wet so I'm not worried about rain. I'm not the first to use these exact vents with this car and other people just leave the vents open all the time and they have no issues. So you recommend tape? I was thinking the epoxy but I don't want it to loosen over time from the heat/rain.

You are essentially joining "dissimilar" materials when you take items that are plastic and "join" them to metal. They have different rates of expansion/contraction and will, yes, no matter how well bonded, crack and try to pull apart. Sometimes it is very minimal and appears as tiny cracks around the attachment points while other times it can be dramatic with larger 1/8 inch cracks appearing. You just don't know how these materials are going to respond. With the tape the contraction and expansion can happen with the tape being the "buffer" between the materials. Car manufacturers almost never graft hood scoops made of dissimilar materials on to hoods. If there is a hood scoop it is molded into the metal or fiberglass hood or even further.... a "shaker" style scoop rides separately with the engine intake with a weather sealed cutout for the shaker scoop.