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 Post subject: closed nose?
PostPosted: June 30, 2011, 1:30 pm 
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Hi all, I'm working on an R1 powered Caterham. The engine sits far enough back that if I wanted to, I could lay the radiator flat on the bottom of the engine bay, in front of the engine. My plan is to suck the air from the bottom, then use duct work to exit the side of the engine bay.

This leaves basically no need for a traditional seven nose - so I'm looking for ideas on what could be done. I'm thinking of some type of low profile closed nose, but not sure how that would look.

The other idea is to use the opening as some sort of ram air, but I think the drag losses will exceed any gains in power.

Thoughts and any pictures appreciated.


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 Post subject: Re: closed nose?
PostPosted: June 30, 2011, 2:18 pm 
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slngsht wrote:
The engine sits far enough back that if I wanted to, I could lay the radiator flat on the bottom of the engine bay, in front of the engine. My plan is to suck the air from the bottom, then use duct work to exit the side of the engine bay.
Yes, I suppose you could do that...But the obvious question is, why would you want to? In order for air to flow through a radiator, there must be a pressure differential with higher pressure on the entry side than on the exit side. There is also a pressure drop across the radiator that the pressure differential must also exceed in order for the air to flow through. The pressure drop is likely rather small, but you are also currently talking about having relatively low pressure zones on both sides of the radiator without knowing how similarly low pressure the two zones might be, and thus it could be a significant portion of the available pressure differential. Which simply put, means minimal cooling airflow. Unless you are driving in a climate that can "air cool" a water cooled engine (Green Bay WI in the winter), or have vast quantities of data collection to validate this theory, I would believe the risk to be far higher than the reward. If you want to place your radiator horizontally, feel free to do so...I just highly recommend that you duct the air in to it from above the splitter.

In theory it could work...

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 Post subject: Re: closed nose?
PostPosted: June 30, 2011, 2:34 pm 
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The reasons for doing it:
Lower center of gravity compared to a vertically standing radiator.
Try to improve the aerodynamics from that of a forklift to a bread truck.
Lower polar inertia - keeping things closer to the center of the car (although I could have a vertically mounted radiator behind the front suspension as well.

I see your point about pressure differential, but the fan will be making up the difference (it'll just be on more).
I will be sealing and ducting the air on the back side, and venting it to a pocket that i'm opening on the right side of the chassis side for exhausting this air.


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 Post subject: Re: closed nose?
PostPosted: June 30, 2011, 6:35 pm 
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I tought it might be nice to put a radiator across the rear of the car, to help fill in the vacuum with a little hot air. Maybe not very practical.

Have you bought an engine yet? I think you can get a 1400 cc Kawasaki that might be a little easier to drive. Is this for track only?

Can you live without a V8?

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 Post subject: Re: closed nose?
PostPosted: June 30, 2011, 7:08 pm 
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horizenjob wrote:
I tought it might be nice to put a radiator across the rear of the car, to help fill in the vacuum with a little hot air. Maybe not very practical.

Have you bought an engine yet? I think you can get a 1400 cc Kawasaki that might be a little easier to drive. Is this for track only?

Can you live without a V8?


Yeah. I got a smokin deal for the works that was impossible to turn down.

Engine was included. My thoughts right now is track only, but that might change if drivability is not too bad. My goal is to stay on the light side of 800 lbs. We'll see if that's doable.

Will I miss the V8? Hell yeah. Frankn7 was an absolute blast, and she won't be far. My nephew is taking over, so it'll be on the family.


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 Post subject: Re: closed nose?
PostPosted: June 30, 2011, 8:11 pm 
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I second Justin's idea of ducting air in from the top. You might be able to make a splitter work to your advantage. Unless you add a full undertray of sorts, the belly of a 7 isn't really conducive to being an aerodynamic device.

With a splitter you might be able to get some sort of low pressure directly below the nose then duct the air in through either the standard grill or a smaller version* of the standard grill.

*You typically want to slow the air before it enters the radiator anyways - a small opening into a plenum/diffuser of sorts would do the trick.

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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 12:09 am 
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I do plan on a completely enclosed bottom to the car. I did the same with Frankn7 - the only open piece was under the oil pan (flat LS1 oil pan) and filter, and even that could've been paneled off.

I guess I'll have to do some thinking on air pressures.


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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 12:51 am 
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SLNGSHT, so you have a LS1 in your car? And you are enclosing the whole bottom of the car? Hmmmmmmmmm?
All that hot air has to go somewhere. My bottom is open back to the foot wells and the tunnel. Those LS1's do disipate quite a bit of heatand I'm thinking of putting a fan near the diff to draw that hot air down the tunnel and out the rear................

AL :chev:


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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 5:49 am 
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Yo Slngsht-
You can get most of the advantages you talk about, lower CG, better aero, etc, with a radiator that is angled forward (as opposed to leaning back like so many Se7ens do) with a low, wide intake opening. You can then duct the air out the top through openings in the front part of the hood and maybe even create a bit of downforce.
Attachment:
Chassis w laydown rad.jpg
Chassis w laydown rad.jpg [ 50.29 KiB | Viewed 1917 times ]
Here's the layout I'm talking about, although you could put the rad further back inside the frame if you wanted to.
Attachment:
PurpleMallock.jpg
PurpleMallock.jpg [ 195.19 KiB | Viewed 1917 times ]
Here's a similar car with the bodywork on. You can see the air extraction vent in the nose. Note the small raised lip in front of it to help produce low pressure and move the air out and up.

Just my .02, but for you, no charge!
:cheers:

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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 7:34 am 
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One big advantage to the flat mounted radiator would be protection from the idiots who pull up until they hit the car in front of them when parking.

You have to stop somewhere, and "if you park it, they will come."


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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 9:13 am 
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GonzoRacer wrote:
Yo Slngsht-
You can get most of the advantages you talk about, lower CG, better aero, etc, with a radiator that is angled forward (as opposed to leaning back like so many Se7ens do) with a low, wide intake opening. You can then duct the air out the top through openings in the front part of the hood and maybe even create a bit of downforce.
Attachment:
Chassis w laydown rad.jpg
Here's the layout I'm talking about, although you could put the rad further back inside the frame if you wanted to.
Attachment:
PurpleMallock.jpg
Here's a similar car with the bodywork on. You can see the air extraction vent in the nose. Note the small raised lip in front of it to help produce low pressure and move the air out and up.

Just my .02, but for you, no charge!
:cheers:


LOL, Thanks. Interesting body on that car. I'll see what I can do with slanting the rad. It'd still be great to keep it in the engine bay - seems like a total waste to have a couple square feet of empty space with nothing in it, then have to extend the body to cover the slanted rad in front. Not sure if it's doable though. I'll post some pics tonight of what I'm working with.


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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 9:21 am 
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Quote:
I'll see what I can do with slanting the rad. It'd still be great to keep it in the engine bay - seems like a total waste to have a couple square feet of empty space with nothing in it, then have to extend the body to cover the slanted rad in front. Not sure if it's doable though. I'll post some pics tonight of what I'm working with.


I had that same thought, why not put it inside the frame instead of "hanging out" in the front. Depending on the radiator and the frame size/shape, it's doable...
Attachment:
4 24 11 Rad in Place.JPG
4 24 11 Rad in Place.JPG [ 345.23 KiB | Viewed 1898 times ]

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"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 9:46 am 
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The only downsides to putting it in the engine bay is accessibility to the front of the engine and the limited space to build the ducting thru the hood.

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 Post subject: Re: closed nose?
PostPosted: July 1, 2011, 5:41 pm 
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Well, I don't know much about design, but I did notice something odd at the GP of Europe (Vallencia) last weekend. The air temp was in the high 70's and the track temp was over 100. I know you don't want intake air from track level and I wouldn't think you'd want cooling air from there either.

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 Post subject: Re: closed nose?
PostPosted: July 2, 2011, 2:09 pm 
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Under the car is typically lower pressure, thus a vacuum, fighting your plan to suck air from the bottom of the car, unless you added a scoop of some sort. The suction (venturi effect, basically) you'd get from vents out the side of the engine bay would definitely not be substantial enough to do any actual cooling, it's enough to vent hot air from the engine bay with a conventional nose, but not to cool the engine. A closed front end would also give you extra heat in the engine bay, generally a bad environment for a radiator.

The cg would see very, very little change for what it's worth, compared to a slanted rad. There's just not enough weight there to justify it over a 30-45 deg slanted one, especially if you're using the stock R1 radiator.

As for aero, the nose isn't the car's real issue. It's cross sectional area remains the same, and the main problem (awful airflow off the back end) remains. You'd see a reduction in front end lift, maybe, but that's already doable with some ducting and vents in the existing nose (see caterham CSR) without encountering issues with airflow over the rad.


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