extra cooling vents?
Discussion
What with the amount of heat under the bonnet, I was musing about having some extra vents cut into the bonnet of my car. Just a couple, not to big. 2 around the rad area and 2 further up near to the manifolds. They would be about 2 inches wide and 5 inches long. Has anyone tried this? I would keep the mesh black and low key, not Max power! Cheers.
IMHO you shouldn't need to... If your cooling system is in tip top condition and your fans work, there shouldn't be a problem in the first place! Maybe try getting an otter switch that brings the fans on a bit earlier? The best way of reducing the under bonnet temps i've found is to replace the manifolds with ACT sports decat ones - drops the running temp by 10 degrees and sounds like the devils car!
One thing to bear in mind, if you put vents in the front of your bonnet it increases underbonnet pressures, which tends to make the problem worse. (and on a Chimn will probably pop your bonnet open when your going very fast). You want to be letting air out of the bonnet, to reduce under bonnet pressure and hence draw more air through the radiator. Thats if you really want to chop up your Chim, which I wouldnt.
That's more or less exactly what I did to mine. The vents allow heat to convect out of the engine bay when it's in traffic, and at speed the lift from the bonnet is substantially reduced and the whole engine bay runs a lot cooler. The higher the speed the greater the suction pulling hot air out of the engine bay, which is obvious, but it still looks wierd at three figure speeds to see wool tufts standing straight up despite the headwind. The disadvantages are mainly looks (I quite like them, no doubt opinions will differ) and the fact that heavy rain can get onto the exhaust manifolds and produce vast clouds of steam from time to time. Oh, and if you're into that car cleaning thing that some people do, you'll need to be a little more careful around the vents.
RumbleBee said:
One thing to bear in mind, if you put vents in the front of your bonnet it increases underbonnet pressures, which tends to make the problem worse. (and on a Chimn will probably pop your bonnet open when your going very fast). You want to be letting air out of the bonnet, to reduce under bonnet pressure and hence draw more air through the radiator. Thats if you really want to chop up your Chim, which I wouldnt.
So the vents would need to be closer to the rear of the bonnet? This way the air is sucked out? Would putting the fans in front of the rad instead of behind be any better? fat tony said:
RumbleBee said:
One thing to bear in mind, if you put vents in the front of your bonnet it increases underbonnet pressures, which tends to make the problem worse. (and on a Chimn will probably pop your bonnet open when your going very fast). You want to be letting air out of the bonnet, to reduce under bonnet pressure and hence draw more air through the radiator. Thats if you really want to chop up your Chim, which I wouldnt.
So the vents would need to be closer to the rear of the bonnet? This way the air is sucked out? Would putting the fans in front of the rad instead of behind be any better? 
My cooling system is good, I was just looking to get rid of some of the heat whilst in traffic etc. I was sat in traffic a while back and it went up to 100. I found the fan cables loose I tightened them up, and this sorted the fans out. I just thought a couple of vents would help when sat still. New to the tvr world, and had to much time on my hands. You know the old saying "devil makes work etc!"
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