Side Vents

External options and variations: rear end mods, side vents, doors, cage mods, wings(!), etc.
ekim952522000
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Re: Side Vents

Postby ekim952522000 » 01 Mar 2010, 23:55

2 votes for sixth down

me and the wife..

P.S. where are my updated drawings :D j/k
Mike Uhlinger
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Pez
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Re: Side Vents

Postby Pez » 02 Mar 2010, 06:27

Love the Sketches.

I think the large vent looks better as I feel it suits the car more.

You could have the filler on the top as you have mentioned on one side and the Intercooler mounted horizontally on the flat part on the other side.
I would look really good IMO and also break up the large flat area a bit, might also stop some stones from Mashing it too :o

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Re: Side Vents

Postby Midlana1 » 02 Mar 2010, 06:58

Most people (here and elsewhere) prefer the first one. Justin's trying to talk me into a NACA duct which, if it works, might look pretty good. It also has the benefit of not collecting as much road debris as these others, but of course a screen could deal with that, too.

I'll ask our aeronautical guys here at work their thoughts on these.

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Re: Side Vents

Postby Midlana1 » 02 Mar 2010, 07:35

Pez wrote:... You could have the filler on the top as you have mentioned on one side and the Intercooler mounted horizontally on the flat part on the other side...

It's real hard to say how much airflow there'd be. It's not clear that the pressure differential across it in that position would be any better than having it inside the engine compartment, ducted to the vent. Also, with it inside, the plumbing to and from it is shorter.

I came up with a quote for the book, "Discussing aerodynamics without data is like debating religion."

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Re: Side Vents

Postby Midlana1 » 02 Mar 2010, 13:25

My brother brought up a few points:
1. How many cones will I hit, few to none, and those that do hit will bend the fender back, which the tire will brace. I can alway add a brace tube across the bottom inside face of the fender.
2. I'll get a lot of rocks in the vent, but I'll have "drain holes" for water, and sand and pebbles.
3. He says his fenders aren't just blasted, but seriously chipped - plan on a ruined paint job in one year.
4. He's going to use bed-liner to protect the fenders, which will work but look bad.
5. He's going to add fender flaps, hanging down as near to the ground as possible.

So, if I get rid of the nerf tube and add front fender skirts, I still have to get air into the engine. Some sort of vent is still needed, regardless of the above.

There's only about 6-7" from the bottom front edge of the fiberglass fender to the main hoop; that's all there is to work with. The render at the top of this page gives the impression of great depth, that the ducts curves into a deep tunnel, and that's just not true. There's a bottom tube, trailing link, diagonal, and top tube right at the outside edge of the chassis - there is no real "depth." Whatever depth and curvature that's there comes entirely from the ductwork itself.

It's likely I won't have made up my mind by this weekend, and in that case I'll work on wiring the dash, lol.

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Re: Side Vents

Postby dm2play » 02 Mar 2010, 14:57

Instead of bedliner how about 3M tread tape the stuff with the coated grit for stairs. Available at any hardware store.Tuff, light, long lasting, peal it and replace when it does start looking bad. Give your fenders a Caterham look. Or GM uses a color matched wear tape on pickup lower fenders

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Re: Side Vents

Postby Midlana1 » 02 Mar 2010, 14:58

Here's the reply from the aero guy:

Are these brake cooling inlets or engine cooling inlets, or both? (I assume not an engine intake).

Without knowing the cooling requirements, it would not be possible to know what geom. provides adequate cooling. I think you need to be flexible in order to make sure you don’t overheat (be prepared to make it bigger if it doesn’t work). So without a detailed analysis, it will be trial and error (nothing wrong with that).

One design is much larger than the other, so I’m sure the larger one will provide more cooling flow, but then again, how much do you need? I like the idea of making a generic fender (like you did with cardboard) and then put different ‘plates’ on the fender with different size inlets – if you can make that work without too much work and look ok. If that will work, start big and work down (not the other way obviously).

It looks like you are turning the flow very abruptly after entering the intake. It would be best if you could smooth that out. Also, cooling drag is reduced by expanding the flow (slowing it down by making the cross section gradually larger). But that may be beyond the scope of what you are doing. Optimizing for drag is probably secondary to just providing an adequate cooling volume of air.

You may want to consider a fairing aft of the front wheel to reduce the drag, improve flow for the aft inlet, and filter out any debris off of the front wheel. Or maybe just something to filter out the debris only. I suppose you could put a screen aft of the inlet to do that too.

NACA inlet will probably work, but they are not very efficient, so it will need to be bigger for the same cooling flow volume.


I find this part interesting:
You may want to consider a fairing aft of the front wheel to reduce the drag, improve flow for the aft inlet, and filter out any debris off of the front wheel.
This has lots of possibilites, but at the expense of looks and simplicity. Guess we'll see.

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Re: Side Vents

Postby Midlana1 » 02 Mar 2010, 20:58

Another solution is to place the vents on the upper sides of the main roll cage. Later I talked with my buddy, Lee, who said much the same that another internet buddy, Mark Warner, said. That up until now, they feel I'd done a good job moving the Seven into the 21-century while retaining it's elemental shape. However, both feel that by adding the big fenders it completely changes the character - which they feel is not good.

The cone deflector can be a bolt-on affair, installed just for autox events. Front flaps can help protect the rear fenders from rock impacts, and flush vents in the side panels ahead of the fenders well help bleed off high pressure into the engine bay. The upper scoops will - hopefully - duct enough air to the intercooler so high charge temperature won't be an issue.

But, showing it to another buddy, he really liked the first vent, and the fact that it changes its character from a Seven is, to him, a good thing - not everyone likes how the Seven looks. He feels the air scoops up high make the car look top-heavy, which I agree with. So I keep swinging back and forth on this.

Bottom line, builders are free to express their creativity with the fenders anyway they see fit. Each of us have our own opinions on what looks "good", so it's guaranteed that we'll never agree on one design, and that's fine. Builders are encouraged to do their own thing. Like I've said elsewhere, it would suck to have a Midlana meet someday and see rows of identical cars - how boring! This reminds me that it doesn't matter how I do the fenders, as long as I like it.

Exciting times.

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Re: Side Vents

Postby Midlana1 » 05 Mar 2010, 09:19

Received a reply from a buddy who had a Westfield and Elise:

...personally i like the smoother version of the fenders, strictly from looks standpoint - when taken in isolation. would still need to see the whole car before a definitive opinion. they'll still get sandblasted to hell (even my Elise did,to the point of needing magnetic stick-on shields, and it had fully enclosed front wheels). The Westie needed massive mudflaps on the front, hanging down to within 1" of the ground, which helped a lot. The Elise actually had mudflaps from the factory. With the way you have your front fenders drawn right now the rears are going to be destroyed no matter how they're shaped (which means any shape that allows for easily replaceable shields would have points going for it).

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Re: Side Vents

Postby ekim952522000 » 05 Mar 2010, 15:47

I would try to make one out of cardboard like the one in the title of the forum and see what that looks like. All of your current designs go all the way out to the outside edge of the fender. To me leaving some of the rear fender exposed like the one you drew early on ties in the look of the front and rear fenders.

Image
Mike Uhlinger
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