Radiator hood vent?? Aero, cooling, WAI, all in one??

[serialk11r]

The angled radiator is pretty common, it's to lower the center of gravity and fit a larger radiator than you otherwise would be able to given a certain height restriction.

Recall though, the MP4-12C only had radiators sitting in the sides. Supposedly to reduce the amount of piping, but I don't think they would've done it if there wasn't an aerodynamic benefit as well. In that case, they got to vent the radiators straight into the wake.

[Vman455]

Originally Posted by jeff88

P.S. Liking where this thread is going, wasn't sure where it was headed in the beginning, but now it's making me want to cut up my hood and put a big gaping hole in it!

It's making me want to cut up my hood and put a small gaping hole in it.

[freebeard]

Did someone say 'small gaping hole[s]'?

[chillsworld]

Originally Posted by freebeard

Did someone say 'small gaping hole[s]'?

Punched louvers.... YUMMY!

[gone-ot]

What's old (1940's-50's) is new...again!

[chillsworld]

Originally Posted by Old Tele man

What's old (1940's-50's) is new...again!

Good things never go out of style sir... I'd kill to have a mercury with a punched hood... And serious aero/FE mods

But in all seriousness... Would louvers be an appropriate way to test hood venting? Or perhaps even an exterrior form of a ducted radiator? Instead of having a huge gaping hole in your hood, could the duct lead up to a section of well done louvers that wouldn't restrict exit air flow but assist in directing the air where you want it to go?

~C

[whatmaycome14]

Originally Posted by jeff88

now it's making me want to cut up my hood and put a big gaping hole in it!

Me too...

[aerohead]

Originally Posted by chillsworld

Good things never go out of style sir... I'd kill to have a mercury with a punched hood... And serious aero/FE mods

But in all seriousness... Would louvers be an appropriate way to test hood venting? Or perhaps even an exterrior form of a ducted radiator? Instead of having a huge gaping hole in your hood, could the duct lead up to a section of well done louvers that wouldn't restrict exit air flow but assist in directing the air where you want it to go?

~C

Without a wind tunnel,you could tuft your hood,get it up to say 25-mph and photograph it.
Where the tufts were crowding together (I'm thinking near the A-pillars),this would be the lowest pressure area on the hood (Bernouli's Theorem).
This would be the place for the louvers.
If you had a junkyard hood,you could experiment,moving the louvers around,while simultaneously re-skinning the last area investigated.
If the engine bay were airtight,each 'hole' would carry half the volume.
The trick is to get the air out at the same velocity as the air it's flowing into,and directed parallel to that flow.
This is where the louvers slits might not be ideal.
Here is a 'poor' shot of the CNR,you can see how the extractors are aligned with the air/oil trace on the body.The size and orientation of the nozzles required at least $100,000 in tunnel time to dial in.They are perhaps the most scientific extractors on Earth.
http://www.cardesignnews.com/servlet...ICE_CONF_ID=68

[freebeard]

A survey of prior art on Google shows that two rows is most popular situated somewhere away from the center line, consistent with aerohead's example:

The trick is to get the air out at the same velocity as the air it's flowing into,and directed parallel to that flow.

A whole hood-full may be counterproductive here. A sealed engine bay might have them clustered toward the front.

[aerohead]

Originally Posted by freebeard

A survey of prior art on Google shows that two rows is most popular situated somewhere away from the center line, consistent with aerohead's example:




A whole hood-full may be counterproductive here. A sealed engine bay might have them clustered toward the front.

Paul van Valkenburgh,in his race car engineering book talked about a static pressure surveys to establish sweet spots for various locations.
He double-drilled sections of plex,to create static ports,ran Tygon tubing from all of them to a selector valve,and from there to a manometer or Magnehelic to read the pressures.