Hér er svar sem einn fékk á Northloop þegar hann spurði um sama hlut:
"Hi - 'fraid I'm not actually an aerodynamicist, although I do have a masters in Aerospace Engineering and do a fair bit of fluids at work, so have a reasonable knowledge of the subject.
From your posts, it would seem that you goal is to reduce bulkhead temps, by reducing under bonnet temps. You have already done all you can do to reduce radiated heat from the turbo being absorbed by the bulkhead, by fitting heat sheilding. This leaves conduction and convection through the air. Getting the air behind here moving will reduce both of those, but would not be easy. Another way you can go about this is to reduce the heat transfered by all three mechanisms by reducing the temperature of the turbo / downpipe.
The downpipes outside temperature can be reduced by some form of thermal barrier, be it ceramic coating or exhaust rap. There are two ways to reduce the temperature of the turbo itself, and that is flowing air over it, or reducing the oil and / or water temp. Bearing in mind that radiators are designed with maximum surface area in order to conduct heat into a passing fluid - and turbos on the other hand are not!
How is the turbo cooled now? does it have a water jacket?, or is it cooled by the oil? If the under bonnet temps are as high as you say, I would think that the oil and water are getting pretty hot too - maybe a more efficient radiator and / or an oil cooler would be a good idea, and would lower under bonnet temps by keeping the turbo / engine cooler. The efficiency of your existing radiator could be increased by increasing the flow of air through it, using a bonnet vent.
The basic principle with any type of none assisted (pumped) vents etc is that the intake must be in a high pressure region, and the outlet in a low pressure region, thus creating a positive delta across the two inducing a flow.
This is complicated in cooling ducts by virtue of the fluid being heated up as it travels through the duct, and in this case by the fact that the 'duct' is not actually a duct, and flows in the engine bay of a car are likely to be highly turbulent!
A vent about one third of the way back from the front of the bonnet (like your front itegrale vent ) would be in a low pressure region, and would increase flow through the radiator, reducing coolant temps, and under bonnet temps as a consequence. Flowing air over the turbo itself will be much more difficult, and probably not as productive.
If you want to further increase flow through the engine bay, and get some of the air behind the engine moving, then vents in the front wings behind the wheels should help to pull some air through, although this does depend on the design of the inner wings - presume your steering rack passes through here somewhere.
My advise - go with the front 'integrale' vent, and get an oil cooler, if you haven't already. If you still need more cooling, increase the area of the vent, and think about vents in the front wings, behind the wheels.
How out some pictures of your car, and under the bonnet - may help stir the collective creative juices!"
http://z8.invisionfree.com/Northloop/in ... =9225&st=0_________________
Þórður
'99 M5 SC // '89 M3 S85 // '04 Patrol GR
Alpina wrote:
S85 er vondur mótor þó að hann sé kraftmikill...
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