[Fot] under hood temp control

[EDWARD BARNARD]

Steve: When I was building the car that Randy Williams currently owns I went to the CVAR rules committee to ask if I could louver the bonnet. They told me if I did I would need to run the car as a sport racer against other sport racers of the time. Since I thought it unlikely that it could be competitive against the likes of a Lotus 11 or similar cars I chose not to louver the bonnet. They did allow me to open the two bonnet vents as long as it wasn't unsightly. I did have two louvered panels made and I welded them to the inside wheel wells. They can't be seen from the outside when the wheels are mounted, and there is enough stuff under the bonnet to obscure them from view. There is a low pressure area in the wheel wells at speed, and it helps to evacuate the hot air from under the bonnet. 
  Ken G. once told me that in the SoCal region they didn't allow the spacer blocks under the hinges. His trick was to loosen the two nuts that secure the hinges to the scuttle. As speed increased the rear of the bonnet would raise up. When you slowed down the hood would drop back down. During tech everything appeared to be "normal".
  I'm here to say I know that under the bonnet is a high pressure area. Having had a bonnet open at about 40 mph I can  bear witness that the safety latches nor the hinges will keep the bonnet secured to the scuttle. I have the scar from the stitches to prove it. 
  Still dizzy after all these years - Ed

Steven Preiss <spreiss at verizon.net> wrote:
  FOT
I am thinking of making an objective of reducing the air temperature in the
engine compartment of my TR3, and to direct as cool air as possible to the
carburetor intakes. I know there are shrouds available to channel maximum
outside air through the radiator, but that seems to address only part of the
problem. Where does all that heat from the head and exhaust manifold go?
Surely not out those two little slits. Louvered bonnets are an attempt to
address this no doubt, but it seems they are expensive and not universally
done. I know from seat of the pants that as operating temperature rises,
performance dwindles. How do others deal with it?
Steve Preiss
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