Hole through middle of car. Aero benefits?

[SvdM]

This seems to suggest that it should indeed work... provided (naturally) that you don't add to the total frontal area.

F Ducts: How do they work? | F1 2011 | Formula One technology | Racecar Engineering | Race car technology explained
2010-formula-one-technology/

[Frank Lee]

I don't see how that applies to non-winged vehicles.

And I don't think the idea has merit.

[SvdM]

Correct me if I'm wrong, but as far as I see it they're simply talking all fancy and engineering-like about stalling the wing, but in effect all they're doing is filling a low pressure area with air from a higher pressure area, thereby reducing the drag (and it certainly sounds like this was their goal).

I think whether it's a wing or not is slightly irrelevant for drag reduction purposes. It just so happens that since they're F1, have a lot of equipment and knowledge, it pertains to the rear end of a high downforce wing.

I think the idea does have merit, but whether or not it can be accomplished with significant improvements on an every day vehicle will depend on how much 'free' space one might be able to find without increasing the FA.

[ai_vin]

Originally Posted by SvdM

This seems to suggest that it should indeed work... provided (naturally) that you don't add to the total frontal area.

F Ducts: How do they work? | F1 2011 | Formula One technology | Racecar Engineering | Race car technology explained
2010-formula-one-technology/

The first sentence on your link says it all: "When McLaren’s F-Duct system first appeared in pre-season testing it was hailed by many a a true stroke of genius, a classic example of out-thinking the regulations."

"Out thinking the regulations." Race cars are built to a set of rules and this tech is designed to get around those rules. Street legal cars are built to a different set of rules so even if, and it's a big IF, this idea worked with these different rules there are likely easier and better ways of getting to the goals we have. And speaking of goals, race cars are also built for different goals than ours. Who here wants to pull 5 gees in their car?

[Frank Lee]

Ducts have drag; if you have excess interior room you are better off chopping the top or some such.

[SvdM]

@ai_vin
I don't know what 5G has to do with the this... you'll note they used this F-duct system for the long straights to reduce the overall drag of the vehicle. For them it was for top speed, but for Joe Ecomodder it'd be for better fuel economy.

@Frank Lee
I agree, less FA would always win above this. I don't really see this working on many vehicles as components are too tightly packed under the floor. And who'd want to cut a hole through their car inside the cabin, apart from perhaps some die-hard ecomodder with an older cheaper car. I do think there is a lot of scope in perhaps an older pick-up or something similar, since they seem to have a lot of open space between components.

Now lets imagine this older pick-up has already been modded with a flush underbelly from something like coroplast, but now you take it off, stick a pipe or two linking the high pressure front (maybe just aft radiator) to the low pressure back in some space you can find under the chassis and stick your coroplast underbelly back in its original position - hence not increasing the FA. Where one might have vented some of this air out the wheelwells, now you channel it down the smoothest pipe(s) you can make to the back.

Surely this can help and would be easier than fabricating a chopped roof. But yes, I understand how it'd probably not be worth the trouble unless you have a lot of free space to work in that might otherwise have been blocked off.

[Frank Lee]

Higher pressure engine compartment air vents to lower pressure areas anyway... otherwise it wouldn't flow.

Interesting to think about pickups though...

[Sven7]

Wouldn't it be easier to prevent the high pressure via body mods than to cut a freaking hole in your car? In America we can do virtually whatever we want to our cars without consequence. We aren't under draconian FIA rule and I see no reason to go to these lengths for such a small increase. The only time it could possibly be worth it in my opinion is on an already aero'd out car like the Aero Civic.

This is the proverbial "high hanging fruit" that we not only need a ladder for, we need to rent a helicopter to grab it from the very top of the tree. Sure it's fruit and it's on the tree, but unless you've eaten every other apple in the orchard and are still hungry, why do it?

[ai_vin]

Originally Posted by SvdM

@ai_vin
I don't know what 5G has to do with the this... you'll note they used this F-duct system for the long straights to reduce the overall drag of the vehicle.

Exactly, race cars are designed with elements that produce negative lift for going around corners at high speed, but downforce also produces high drag. This tube only reverses some of this at the cost of extra internal drag in the pipe itself.

[orange4boy]

Here's a friction loss graph for ducts... All you have to do is subtract the loss in the duct from the benefit of reduced pressure at the rear and compare that to an unmodified car... Easy!