Vented nose panels
01-06-2006, 01:44 PM
#61
Sorry, I should have been more clear on that. What I mean is that installing an aftermarket vent in the hood (ala 968 Turbo) is pretty much a necessity to make any frontal venting effective. As configured from the factory, the air coming out of the back of the intercooler appears to get trapped, altho I suspect something more may be going on there (by design from Porsche engineering, I suspect or they may have thought it didn't matter, given the apparent performance target of the product) and the math models I was using weren't sophisticated enough to analyze it.
You and I are in agreement on #2.
Regards,
You and I are in agreement on #2.
Regards,
01-06-2006, 02:39 PM
#62
Burning Brakes
I suspect that since Porsche engineers already had the stock structural crossmember that fits behind the IC, they just kept working with that, rather than do a whole new design with better internal flow in mind. As it is, they got the job half done, as the IC inlet ducting is pretty good, but they forgot the outlet ducting.
That said, exit airflow for IC cooling air could probably be improved greatly just by fairing the forward-facing lip on the holes in the crossmember, slotting the verticle aft edge of the header panel, removal of Laust's rear rubber strip, and a good splitter instead of the stock batwing.
Granted, it would not be as good as the big IC exit vent on race cars or the 968 turbo vent, but for minimal tinkering could be much better than stock, and still pretty much look stock, at minimal cost. For reasons you discussed, I'm not a particular fan of the more-holes-in-front modification of the header panel, which seems mainly cosmetic.
Got any knitting yarn? Why not do some tuft tests of IC cooling exit air? It would be interesting to see what happens to air inside the engine bay, just below the hood/header panel gap. Also, to monitor aiflowr at the base of the windshield, when the rubber trim strip is removed from beneath the rear of the hood.
Oil with some soot mixed in also makes a good indicator of flow, if dabbed on the areas to be tested. That's what German sailplane designers used to test airflow at wing/fuselage junctions, etc.: The sooty oil flows with the wind, leaving telltale streaks showing how the airflow goes.
That said, exit airflow for IC cooling air could probably be improved greatly just by fairing the forward-facing lip on the holes in the crossmember, slotting the verticle aft edge of the header panel, removal of Laust's rear rubber strip, and a good splitter instead of the stock batwing.
Granted, it would not be as good as the big IC exit vent on race cars or the 968 turbo vent, but for minimal tinkering could be much better than stock, and still pretty much look stock, at minimal cost. For reasons you discussed, I'm not a particular fan of the more-holes-in-front modification of the header panel, which seems mainly cosmetic.
Got any knitting yarn? Why not do some tuft tests of IC cooling exit air? It would be interesting to see what happens to air inside the engine bay, just below the hood/header panel gap. Also, to monitor aiflowr at the base of the windshield, when the rubber trim strip is removed from beneath the rear of the hood.
Oil with some soot mixed in also makes a good indicator of flow, if dabbed on the areas to be tested. That's what German sailplane designers used to test airflow at wing/fuselage junctions, etc.: The sooty oil flows with the wind, leaving telltale streaks showing how the airflow goes.
