Radiator exhaust through the hood

So I took a different route on this with my old racecar. We didn't want to cut holes in the hood as it was already very light and we worried about their integrity if we put holes in it. So, we took out the small wall between the trunk and the rain tray area. I create a custom fiberglass box from the radiator and then to the rain tray area which then vented out the black rain tray space. The only bitch was the fuel cell was under the fiberglass in the front trunk. Also, before anyone says anything, yes, the strut mounts are installed wrong. We did fix that.
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That just reminded me. Not a Fiat but, back before "aero" was much of a real science and more of a "do what you think looks right" era, we made a very large duct from the radiator all the way through the passenger compartment, and out the back of the car's rear panel.

I suppose if you ice race you could exit it into the passenger compartment for warmth.
 
Dr.Jeff said:
I'm assuming your goal is more about adding brake cooling than to redirect the radiator airflow from under the car? I say that because the proposed size of your ducts don't seem they would allow a significant change in the volume of air from the rad flowing downward. I kind of thought Braden's design was slightly on the small side with respect to the total air volume (surface area) through the rad. These are even smaller. Nothing wrong with that, depending on the goal - brakes vs overall aero.
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Braydens' take up almost 1/2 the width of the tub flat - that section is about 24" wide - So I wouldn't call them small.....

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I think ANY venting of the tub will help, I think the flow will want to go through the wall vs. swirling around the tub before going down & out. In my case, the fans are now pointing more so at the lower tub vs. upwards as with stock setup. I'll see what happens. I can always increase the size down the road.
 
Regarding the size of the openings. If you look at the surface area of the radiator, that's the size the two openings should equal if you are doing it for any aero effect. Otherwise the remaining air will have to flow under the car, which is what you are trying to avoid. So even if you completely opened the rear vertical wall behind the radiator, it still wouldn't be large enough to completely exhaust all of the air without some going underneath.
 
Dr.Jeff said:
Regarding the size of the openings. If you look at the surface area of the radiator, that's the size the two openings should equal if you are doing it for any aero effect. Otherwise the remaining air will have to flow under the car, which is what you are trying to avoid. So even if you completely opened the rear vertical wall behind the radiator, it still wouldn't be large enough to completely exhaust all of the air without some going underneath.
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OK I guess we are at cross purposes - my intention is not to completely vent the tub to obviate any flow needing to go down & under. I don't see any point in that, given the need to remove the entire wall, and then have to deal with channeling through the hood or cowl, which will never match the dimensions of that wall.
 
Brayden_connolly said:
I think I posted about it a few years ago, when I built my car I vented the rad to the wheel wells as "brake ducting". Didn't want to give up the utility of the frunk and still wanted to be able to store the top up front so this was the solution.

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So far has worked well and keeps the front from "floating" at high speeds.
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Did you ever check out the Matra Simca Bagheera? Very similar and same era as the X. After much aero dynamic research (Matra also makes missiles), they decided the best way to vent to the radiator was... through the wheel arches.
 
ArtBasement said:
Did you ever check out the Matra Simca Bagheera? Very similar and same era as the X. After much aero dynamic research (Matra also makes missiles), they decided the best way to vent to the radiator was... through the wheel arches.
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Cool. By chance do you happen to have any of their research data? It would be interesting to read about what they did.
 
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