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Re: Bonnet Scoop/Vents

Posted: Tue Oct 13, 2020 7:07 pm
by Mrbaboon1985
D366Y wrote:
Tue Oct 13, 2020 8:00 am
Mrbaboon1985 wrote:
Sat Oct 10, 2020 4:13 pm
D366Y wrote:
Fri Oct 09, 2020 11:32 am
I think it depends how big you're thinking of going and how big it really needs to be?

Seen a few people modify the bonnet bulge already on the car and put a vent in that which I thought was rather clever 13040584c3fb7aaba0.jpg
I do like that, I wonder where they got the vents for the bulge or whether that's just cut straight into the bulge with no cover inside?
I'm not sure how it's been done but I've seen a few people do it - I'd imagine if you cut straight through the bulge you could just stick some gauze/mesh or similar on the inside of the bulge to catch any crap from going straight into the top of the carb?

Something else I've seen is cutting the whole bonnet bulge off and adding in some metal to increase the height and leaving that gap as well at the same time - have a look at this link ... &start=140
Cut the bulge off, put some metal in to make it higher but kept the same shape, just taller to fit the V8 in. You could theoretically do a similar thing but rathe than fill in to increase the height, just leave it open to air?
Think I like the idea of cutting then bonnet bulge just need to locate a steady hand lol

Re: Bonnet Scoop/Vents

Posted: Sun Oct 18, 2020 10:29 pm
by atomic4

Re: Bonnet Scoop/Vents

Posted: Mon Oct 26, 2020 11:36 am
by Major_Tom ... Action.htm

Found this interesting article here about aerodynamics, and it contains a short section about how experiments about cooling were done with cutting holes the the bonnet and how, as Martin said, it turned out to not be a great idea (but I don't think they were louvred).

Re: Bonnet Scoop/Vents

Posted: Mon Oct 26, 2020 9:23 pm
"Morning Major"!

Excellent article about the subject, many thanks.

I was seriously thinking about fitting a fibreglass bonnet for two reasons.
a. Save a bit of weight overall, especially at the front with a V6.
b. Install a pair of longitudinal louvred air vents on either side at the rear of the bonnet.
(I didn’t want to desecrate an original bonnet!)
These vents would have come from that well known aerodynamic supplier, found at all good DIY outlets, "Marley".

The thinking behind the louvered bonnet was to extract air close to an area of low pressure at the base of the windscreen in order to overcome an overheating problem.
In other words, crudely following Kamm’s idea but not having a wind tunnel in my garden shed there’s no way of knowing if it would have brought any significant improvements plus, the overheating problem has been solved by replacing the water pump.

Incidentally, in your link I noticed that Tickford arrived at a Cd of 0.37.
A book I’ve got shows the Capri with a Cd of 0.40 (without tail spoiler.) and the same book gives a Renault "Hovis loaf" R4 of having a Cd of 0.39.
Work that one out! :lol:

Finally, the article you provided states,
"note the extra cooling vents."
[in the bonnet]

These "vents" look as though they are to induce air into the engine bay, if so, I would have thought that NACA ducts could have worked better - I was trained to think of vents for extraction – but then, I only have a basic garden shed!

Once again thanks for the input.