This is driving me crazy.

Last week, I saw on the internet, a maker of custom Jaguar XKR hoods (bonnets) and rear trunk (boot) spoilers.

I had bookmarked the site, but can't find it.

The hood that they make fits our XKR Jaguars. It has a higher rise in the middle. There is a vent at the rear near the base of the windshield. It is a subtle looking hood, but the rise is still noticable at about 2" extra in height. It has the openings for the factory XKR hood cooling vents. They say that it provides extra cooling (may or may not be true, I haven't seen a test that verifies). It is expensive and costs around $4,000 USD. I believe that it is made in England or Germany.

They also make a trunk spoiler that looks very much like the one in the photo below. I believe that they do not make the rear bumper in the photo. I believe that they only offer the custom hood and trunk spoiler as their sole exterior modification products.

Does anyone know who makes the custom hood that I have described?

 

http://www.arden.de/uploads/tx_sbdow...8_01-05_en.pdf

Here is a link to Arden,they make the hood.The only problemis it has to be done in Germany. There is a company inthe UK working on one as well.

Paragon Design UK - Products

Contact Tony & ask him how the project is going.

 

This one?



Can't see why it would have to be fitted by them in-house, surely must be possible to just ship a finished bonnet to you.

 

In general if you see some ridiculously expensive add-on or mod for these cars, you can count on it being Arden.

Doug

 

That was my first suspect ... but it is nice ...

 

Would doubt the effectives for extra cooling, as in that area you have a high pressure zone.

So while maybe stationary that extra hole will let heat out, but during driving it possibly works the other way around by pushing air in, and that reduces the effectiveness of the radiators. You're way better of making a front spoiler (to increase frontal area) to increase the low pressure under the engine which will then direct more airflow over the radiators.

The original vents at that particular location does the same, as there are located on a low pressure zone, again supporting more airflow over the radiators.

If you like the looks, its probably be cheaper to have a local body shop make it for you.

Edit: Tried to search for a nice picture showing airflow, and found one where also its better described what happens:
http://southrnfresh.com/wordpress/wh...e-of-your-car/

I have a 2005 front bumper, which is already slightly better than earlier ones, so that would be a better option if cooling is a concern.

 

LOL amazing how things turn up at the same time..... This is something I am working on, this is just very rough but to give an idea



The rear spoiler is a Zeemax item and the rear bumper is one of mine.....

 

I agree with all this, but I suspect the real motivation behind buying a bonnet like this would be that you can see the hole while you're driving and therefore convince yourself you have an extra 50hp

They do look nice, however

 

I have also done something similar to my track car, that was done for a purpose rather than bullshit. Not that I am saying the Arden hood is but like Avos has said, high pressure area coming off the screen, this is why you have ram air intakes there. So where does the air go? it may even cause lift at speed.... Possibly



I can reproduce this hood easy but a lot more modifications are needed, at least you can fit the new portfolio hood vents if you wish

 

Actually, it resembles an old production class rallycar trick where body modifications are not allowed ... but sloppy panel alignment is legal. It results in added downforce or at least reduced lift.

 

Here is a picture of my hood with salt accumulation from highway driving.

It sort of proves 3 points, 1) air is coming out of the vents, and 2) you can see the high pressure build up in the middle as is pushed outwards, and 3) I need to wash my car more often.

 

Is that add-on piece cut from another bonnet?

 

That's funny, when I had gone back to the Arden website I couldn't find the hood.

I agree with AVos, that the rear vent on the hood, if allowed to be operational, would cause a problem by serving as an induction cowl, the opposite needs for our vehicles' cooling needs.

That pic of AVos' dirty hood is perfect! I love shots like those. When I develop aerodynamic shells for human powered racing vehicles, I've intentionally gotten them dirty so that the lines will show up, yielding evidence of the aerodynamic effects without having to rent a wind tunnel. Hah!

My interest in the hood is more about appearance. If I were to get it (that's too much money) it would be for the aesthetics. When I modify the appearance of my vehicle I want for it to be subtle. The rear vent would be non-functional if installed on my car. I can sculpt the hood myself and will probably hire a local fellow that is talented with steel to do the modification prior to painting.

This is such a great forum... you folks responded with far more information than I had expected to see.

 

It is interesting to see in the dirt/rain/salt photo that AVos has provided that the air delaminates from the front of the hood's boundary layer at approximately 3" past the front of the hood's dual cooling vents.

Since the windshield behind it causes a major uplift of the air, it probably wouldn't do much good to see how turbulators would affect the lengthening of the bonding of the boundary layer, maintaining greater laminar flow. It 's also possible that greater laminar flow, up front on the hood, could send more air upward at the top of the windshield, increasing overall aerodynamic drag.

I suspect that having turbulators a few inches back from the front of the windshield, on the roof of a coupe, could actually improve gas mileage and top speed by extending laminar flow at the roof line.

Alas, I have a convertible, and this is just fun conjecture.

 

These expensive mods will DEFINITELY make your car go faster since your wallet has been considerably lightened!

Doug

 

Why not have the hood made in aluminium or the ungoldy expensive CF? It would reduce weight and might help a little in acceleration and cornering.

 

Indeed it is

It is a composite hood, all you need is a frame as below, then add the skin, lighter and you can play



Take another skin and you can see where I taped to make the cuts



Bond the 2 together, blend the edges, take a mould, start producing

 

Nah. I was just asking because a metal piece and hammer welding obviates risks of stress cracks typically seen on bonded on pieces.