Sixfire gets bonnet vents

[Gt6s]

Re commissioning the Sixfire 2500 after a long lay up. The bonnet was removed for an overdue engine refresh. Pic shows new oles in FG bonnet with 304 stainless steel mesh and allen domed head screws. Screws will be exposed and contrasting to achieve that modified look. Do not want her confused with an ordinary Spit
Mesh will be removed again prior to a repaint, dry build only.
Laurence

[Paudman]

Nice one Lawrence, I haven't seen the Sixfire in the flesh in an age. Looking forward to seeing it back on the road.

[Gt6s]

Thank you Colin. Great to see you have SAL out again too.                                                                                                                                                                                                      Laurence

[Nick Jones]

That looks tidy.  Where do you get that nice woven mesh from?

Nick

[Gt6s]

Thanks. The bay of much evil Nick 30mm X 30mm sheet. A sheet does the two vents, available in different gauges 1.2 mm if I remember correctly. ( Pretty sure a stainless steel stockholder will have much bigger.) Cut in half on my sheer, otherwise it would have been a bitch to cut.

Laurence

[JohnD]

Laurence,

Having had the opoortunity to examine some modern competition cars, in particular Ford Rally Focus, I was pleased to find that my research into extractors when I built Old Blue is still valid.  Then I found Prof. Joe Zatz's "Race Car Aerodynamics" where he points out that the slow-movng boundary layer, next to the bodywork, needs to be disturbed to bring the high energy, ambient flow into play, to energise air in the vent and move it outwards.   

The principle need is for a 'tripping lip' in front of the vent, to cause a vortex over it that breaks up the boundary layer.  The vent will also benefit from a floor, that should not be angled at more than 15 degrees.   This is how I implemented it on Old Blue, and below, how Ford does so on the Focus.

Hope that helps improve your design!   John

PS Managed to get the Focus pic in, not the Old Blue, due to board restrictions.  Sorry!

[Gt6s]

Design Design ? It is not a FN design John. Just vent oles to allow the release of pressure from under the bonnet also to aid cooling and allow cooler air to the carbs. As far as I am concerned Job done and out of the way, apart from rounding off the edges prior to paint. More pressing stuff needs to be done on the Sixffire first. Engine and box, to refit, a new Quaife to fit, finish welding on the new rear guards, also a bit of rot repair near the boot floor. THEN PAINT ! But thanks anyway.

Laurence