Diy; The Hood Hack.

[403_r32]

Taken from s2ki.com forums.

(Yes, there are pictures of a Honda, I am sorry in advance.

)

*disclaimer* I take no responsibility if you mess up!

I wanted a vented hood for three reasons;

1. To let heat (from header, engine, & radiator) escape from engine bay

2. To get cooler air into intake

3. To use the low pressure area above the hood to help extract air from under the front of the car thereby increasing velocity under the splitter and floor of the nose which should increase downforce.

Why not buy a carbon fiber vented hood? The affordable knock-off carbon hoods are heavier and less stiff than the stock aluminum hood. I believe the stock hood weighs 14 pounds. The high quality "authentic" hoods (cwest, mugen etc...) cost a bundle and still need to be painted unless you are going for the carbon look. Some if not all composite hoods require hood pins for high speed use. Oh yeah, and I'm cheap. I planned on venting both sides but ran out of time and decided I like the look of just one side. Still debating.

Here's my solution:

How to build your own:

Please use appropriate safety equipment and don't screw up.

Yes, you are about to cut holes in a perfectly good hood so be prepared.

Remove the hood and the hood liner and support it upside down on some padded saw horses.

Make templates by laying paper over each support hole you wish to cut and trace the edge (use the pencil rubbing technique). Use the templates to cut out some perforated aluminum (clean and paint the both sides of the aluminum). http://www.mcmaster.com/

Use a 3/8" spacer against the hood support edges to draw the hole shape. I left a 3/8" lip for mounting purposes.

Using a UniBit, drill a hole in each corner.

Using an air saw, cut out the shape from the under side - leave a small gap to finish off with sanding.

Use a sanding drum on a die grinder to smooth to shape. I tried using a sandpaper wheel on an angle grinder but it gets too hot and the paints starts to peel back.

Once the shape is close, flip the hood over and apply masking tape on the top side all around the new openings.

Use wet dry sandpaper to smooth the cut and feather the paint. The masking tape is there so if you slip with the sandpaper, you won't scratch up your hood.

Lay 3M double stick tape used for moldings/body work on your 3/8" lip and trim with a razor to fit just inside the cut out (find it at automotive body shops).

Use a fine paint brush and carefully paint the exposed edge with factory touch up paint.

Install perforated aluminum and your done. I used some small sheet metal clips to hold the perforated aluminum in place just in case the double stick tape failed due to engine heat but I ran a full track day without them and everything was fine.

[typevu]

Nicely done very neat

[DRD-00F]

that actually looks pretty damn sick!

if only i had an air saw...

[DECIM8]

That almost makes me want to do it to my car... except im scared

[DRD-00F]

That almost makes me want to do it to my car... except im scared

*dances* i got a spare bonnet

[Craved]

Just be aware that the underside of the r33 bonnets dont have a fancy tear drop design to cut around like the S2K .. so you'll have to get imaginative in regards to cut outs that look neat as above.

[DRD-00F]

yeah i got home way to late to even have a look... i figured we would get some ghey design

oh well, ill think about it anyway...

[Ant97GTR]

Also be aware that in Oz any hole you cut in your bonnet (meshed or not) are 'illegal' and defectable due to ADR's.

[DRD-00F]

then it will suit the rest of the car

[DECIM8]

holes can be cut as long as the structural integrity is not f**kd..i.e dont cut the under carrage.

[Ant97GTR]

DRD-00F - Hahahahaha

holes can be cut as long as the structural integrity is not f**kd..i.e dont cut the under carrage.

Wrong. According to ADR's any hole cut in the bonnet whether it is covered in mesh or not is illegal...apparently it can spray any oil leaked by the engine on the windscreen people generally don't get picked on this but it is a possibility.

[monkeykplunk]

So some of the newer model vehicles around that come with a factory option vented bonnet?

Would that not make them illegal straight from the factory?

[N1GTR]

Looks good

[DjeMz]

DRD-00F - Hahahahaha

Wrong. According to ADR's any hole cut in the bonnet whether it is covered in mesh or not is illegal...apparently it can spray any oil leaked by the engine on the windscreen people generally don't get picked on this but it is a possibility.

Any hole? even for a bonnet pin?

So some of the newer model vehicles around that come with a factory option vented bonnet?

Would that not make them illegal straight from the factory?

If you get it engineered it should be fine.

[Kozeyekan]

DRD-00F - Hahahahaha

Wrong. According to ADR's any hole cut in the bonnet whether it is covered in mesh or not is illegal...apparently it can spray any oil leaked by the engine on the windscreen people generally don't get picked on this but it is a possibility.

I've got the VIC ADR's linked below.

Section 10 deals with body chassis alterations, and in that it says that needs approval for modifications of any panel forward of the firewall, though it goes on to talk about cut and shuts being OK.

Later on, section 14 talks about bonnet and hood scoops, stating that it may be fitted if it is an option offered by the manufacturer to a model or series, so I guess you could argue that nismo offered vented bonnets, and they're part of nissan (though if they are covered by the term "Manufacturer" is debateable), but importantly, goes on to add "OR:" and lists the protrusion tolerances.

THEN in the QandA file, it's got frequently asked questions, and the 5th one involves non factory bonnet scoops, and the reply is that they are allowed, visibility permitting.

Because the bonnet is at an angle, it is technically a "Scoop" (i.e., the back is higher than the front, hence air is "scooped" in to the engine bay) The ADRs don't seem to mention anything about the need to cover the hole, and even allows for rear facing scoops.

It seems that you'd definately be able to argue in favour if the hole had a scoop on it, but might be up to interpretation if it's just meshed, unless Honda had a vented bonnet at some stage. Still, with a job that looks that good, you could probably claim it was like that from the shop. Still, I think you'd be OK, as the hole IS technically a scoop.

I like the look of it though. Too bad skylines aren't as artistic with their re-enforcing.

ADRs.pdf

QandA.pdf

Edited October 3, 2007 by Kozeyekan