bottom-IC ala callaway
08-11-2008 | 10:17 PM
#61
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From: long gone.....
i know, i said that on the same post with the pic of the GT3, just worded differently 
i was only using it as an example for what a vent could look like/be located. it wouldnt work too well though because the edge of the hood is too far forward for good airflow.
yea i know. i just thought maybe it would be good to have a protected opening (theres a grille on the evo vent) rather than just a straight hole out of the IC to keep squirrels n **** out lol.
its a shame we cant create a dyno that simulates real driving conditions (amount of airflow). maybe if you installed a set of rollers in a wind tunnel...lol. just imagine the numbers ST's car would put down with a bunch of airflow across the IC.
but where on the 951 could you put a seal for an IC duct? on the 968TRS its doable because the IC is out in the open up front, but on the 951 the thing is hidden away. unless you want to make some sort of air tunnel that goes directly from the engine-side of the nose panel up through the hood...
did you delete the popup lights or do you make more power than stock? i would think the lights on at night would cause quite a bit of drag on the car.
this is a really informative thread, not just for my own use but for others who have similar questions. you guys are really helpful and knowledgeable and i thank you
i was only using it as an example for what a vent could look like/be located. it wouldnt work too well though because the edge of the hood is too far forward for good airflow. yea i know. i just thought maybe it would be good to have a protected opening (theres a grille on the evo vent) rather than just a straight hole out of the IC to keep squirrels n **** out lol.
its a shame we cant create a dyno that simulates real driving conditions (amount of airflow). maybe if you installed a set of rollers in a wind tunnel...lol. just imagine the numbers ST's car would put down with a bunch of airflow across the IC.
but where on the 951 could you put a seal for an IC duct? on the 968TRS its doable because the IC is out in the open up front, but on the 951 the thing is hidden away. unless you want to make some sort of air tunnel that goes directly from the engine-side of the nose panel up through the hood...
did you delete the popup lights or do you make more power than stock? i would think the lights on at night would cause quite a bit of drag on the car.
this is a really informative thread, not just for my own use but for others who have similar questions. you guys are really helpful and knowledgeable and i thank you
08-11-2008 | 10:18 PM
#62
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From: long gone.....
I read that some years agao, when the 996 GT2 came out. If it's wrong than so were they. I'm not married to the info, per se. I believe it was in Road and Track.
08-12-2008 | 01:45 PM
#63
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From: Phila.
there is no disputing the reason for the vent on the 996 GT3 Cup, 996 GT2, 997GT3, 997GT2....the air accelerates over the nose, loses pressure, and helps pull the hot air from those cars' center radiators through that vent. There is a plastic duct that directs the air to that vent, much like there is a plastic vent that directs air in to the 944 Turbo's intercooler.
08-13-2008 | 07:05 AM
#64
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Are you talking about that slim vent in front of the hood lip on GT3's? If so that is primarily for venting purposes as they have an extra oil cooler there that the road cars don't have. It may very well create some downforce from the fact you are diverting/deflecting air upwards so you will get a corresponding downwards force, but at the very slight angle you are deflecting the air as it travels (and slows) through the radiator and out of the vent you are not getting much resulting downforce. But at high speeds it might be noticable.
08-13-2008 | 01:33 PM
#65
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Rainman
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i figure that the hot air coming out the back of that radiator when it shoots out the top of the hood probably creates a high pressure area above the car to push it down
08-13-2008 | 01:36 PM
#66
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From: long gone.....
Like I said, the info was something I read in R&T. I'm not married to it.
08-13-2008 | 02:03 PM
#67
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From: Phila.
ehall you're not thinking about it correctly, V2 maybe right the hotter air may create some downforce on the hood until it hits the windsheild and accelerates and loses pressure. I think you're thinking because the density of high pressure air is low it is lighter...but think about it, high PRESSURE...it is exerting a force on the car, doesn't matter what the density is.
08-13-2008 | 02:30 PM
#68
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From: long gone.....
ehall you're not thinking about it correctly, V2 maybe right the hotter air may create some downforce on the hood until it hits the windsheild and accelerates and loses pressure. I think you're thinking because the density of high pressure air is low it is lighter...but think about it, high PRESSURE...it is exerting a force on the car, doesn't matter what the density is.
At a stand still, the high pressure air will just float upwards, until it runs into something to stop it.
Heat rises because it is lighter.
08-13-2008 | 03:41 PM
#69
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From: Phila.
Right, the air is accelerated over the nose, loses pressure and thus the air over the duct area is a low pressure area, which allows the higher pressure air flowing through the radiator an easier exit (you can say the lower pressure air is helping to suck it through the radiator)...we agree on that, I think the part we disagree on is what effect that higher pressure air has on the car after it exits the duct..what I gather from what you are saying is it just floats upwards and exherts no downward force on the car because higher pressure air is less dense.
08-14-2008 | 08:16 AM
#70
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From: Derby, UK
the air after it has flowed through the radiator is not higher pressure than the air flowing over the car - it is the same. The air flowing over the car is creating the venturi effect that creates a low pressure depression behind the radiator. The air in front of the radiator is slowed down, as rads are huge restrictions, so increases the pressure of the air (though not above ambient pressure as you can't have RAM effect at subsonic speeds), so there is a pressure differential accross the rad. Once the air has passed through the rad its pressure has equalised with that of the air flowing over the car.
So the air exiting the duct is at the same pressure as the air flowing over the car so no downforce is created. It simply mixes with the airflow. It will also cool very quickly to the ambient temp outside the car.
So the air exiting the duct is at the same pressure as the air flowing over the car so no downforce is created. It simply mixes with the airflow. It will also cool very quickly to the ambient temp outside the car.
