Greetings all,

Finally have the car back on the road- tax, test, insured, new wheels and tires, carburettor, clutch cable (wow- the difference!) and a bunch of other bits.

However, I have always had a problem with the engine bay pressurising and causing the bonnet to jump up and down alarmingly at speed.

By temporarily removing the firewall panel the bonnet settled down so it proves that I need to let the air out somewhere!

I was thinking of doing this at the sides of the bodywork down beside the footwell/exhaust as opposed to in the bonnet.

Is this the correct course or should I be doing the Dax trick of stepping the side panel out 1 inch at the firewall so you get a vent?

What size mesh is most appropriate over the holes?

Any pics of what you've done?

Cheers,
James
ETA: Any engine bay vent pics very welcome!


[Edited on 6/5/14 by James]

I was having problems with oil temperatures, which I fixed by opening out the rear gap on the engine bay side panels (on my car these panels end around where the firewall is). It was 15 mm each side, which wasn't working - now increased to 35 mm on the exhaust side. Will do the other side to match when I get around to it, but just doing the exhaust side seems to have sorted it.

(In my case moving the oil cooler in front of the radiator would also have worked, but this has the advantage of reducing engine bay temperatures generally so perhaps a better solution, certainly easier than moving the oil cooler.)

the 'dax trick' does seem to work for most people and it can be made to look quite good IMHO

but you could put any style of vent you like in the same place really, you could even go for the classic louvered side panels / bonnet
(someone on here posted a guide to making your own out of alloy)

[Edited on 6/5/2014 by mcerd1]

Works for our's


Bonnet Vents both sides

Hi James

I used these guys (I think they were nr. Alton, Hants)

http://www.coollouvres.co.uk/index.html

Cheers
Gary

I just lifted rear of bonnet 5mm

James, I used cool louvres to stamp my bonnet.


matching helmet

That and a ducted rad, help no end.


rad duct 02


Description

Regards Dan.

Its one eye on the road and one on the temperature gauge for a small block chevy in a Seven.

I put louvres in the top of the bonnet to move the ambient above the block away but the biggest change was making some holes in the nose and inserting 3 series kidney grills in. Looks nice and cheap.

Oil rad in front of a recored rad.

Valvoline racing oil.
Pacet fan (the best fitting and most efficient on pull from behind)
Perfect mix of anti freeze and water

After that no problem !

I am with Dan (Scutter) on this one.

My Locoblade is flat floored and has a ducted nose.
No over heating issues at all.

I believe Dan had a hand in the design and construction of the ductiing and the flat floor.


Description


Description


Description


Description


Description

The best addition that both Matt the previous owner of Jacks car and I did was to fit a Gurney flap to the leading edge lip of the duct exit. This prevents the air flowing over the nose spilling into the low pressure area in the duct.

I'm planning on side venting mine out of the front suspension area on the V6 as I don't want hot air going into the bonnet bulge.

Regards Dan.

quote:

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Originally posted by scutter
James, I used cool louvres to stamp my bonnet.


Regards Dan.

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Costly , True James, mine cost £140, 10 years ago. BUT very effective. Mesh is pre-coloured Halfords special

Regards Dan.

I fitted a vent near to the exhaust manifold to encourage airflow past the main source of heat and out through the side. The vent was home made.


[img]
Scuttle 2008 [/img]
[img]
Vent 2008 [/img]


David

Why doesn't the hot air exit through the bottom of the engine bay as it is completely open? Is it a high pressure area underneath?