Wasting that heat more efficiently
 

One of the major enemies of drag is the cooling package with it's gaping
holes in the front of the vehicle. I know a lot of ecomodders are using grill blocks or partial grill blocks due to the obvious overheating problem.

Every time I open a hood on a vehicle I find myself looking for unused space in the engine bay area where an extra radiator could be housed.

The extra radiator could be one or more heater core(s) or what ever fits and could be plumbed in with the cooling system. My car for example has plenty of room between the front bumper and a/c condenser for two heater cores.

I keep thinking if there was more surface area for the coolant to get rid of heat,we could possibly completely do away with the air inlet openings on the front of our vehicles or at least just have a tiny opening and benefit from the aero advantages.

Even if you had a full belly pan,there might be enough ventilation around the wheels/front suspension to be sufficient cooling but this would all depend on vehicle and individual driving style,rout,mods,etc.

Of course plumbing would require special T-fittings or splitters,hoses or adapters but I don't want to get into that part now.

Would this work?
Would it be just a lot of hassle for not so much gains?
What's your take on it guys? I'm just brain storming here.

Barna

It would take a lot of work, but you could thermally bond copper tubing to parts of the metal shell to make it act as a heatsink.

Interesting idea. How about a hood made of aluiminum that acts as a heat sink? The problem I see with both of these ideas is the lack of air movement when a fan needs to run to cool things off. My question is, how much can one gain by entirely blocking off the grill?

Is the air behind your current rad close to the coolant temperature? If so, there's not much to gain by adding area. There is a lot more to be gained just by excellent ducting and controlled openings.

I completely agree with Bob. If you don't have much airflow (and you won't with a full grill block), the air thats already gone through the radiator is gonna be very hot and not capable of absorbing much more heat. You'll get less and less cooling from the same amount of surface area to the point where its almost going to be useless and just adding unnecessary weight.

Since I am running a full grill block year round on my Paseo, an idea I had was to use an aluminum belly pan and braze copper tubing to it. I would run that in parallel or series with the radiator for additional cooling. I don't like the aluminum hood idea due to possible injury from a 200F+ hood.

Honestly, with my 21 mile commute, my radiator fan comes on at most (peak heat in summer afternoon driving) a half dozen times for 10-15 seconds. I just deal with it and basically use the capacity of the cooling system to do the majority of my cooling. This is obviously not a good idea for longer trips though.

Salty water on an aluminum/copper tray could be a short-lived arrangement. I'd stick with aluminum tubing for a surface rad. Zinc-based brazing is easy, and gives minimal galvanic action, still eating the aluminum. To get a sense of the size needed, imagine spreading out the innards of a standard rad. The surface rads on a snowmobile depend on a snow spray. The freezer compartments of old refrigerators might be unwrapped to lay flat.

It could be possible to add fins to improve heatsinking, but I'm not sure what it would do to aerodynamics. Probably not much if the fins are thin and not too dense. Maybe something like 1-2cm high by 1mm thick, spaced 0.5-1cm apart, and tapered at the front and back to conform to an aerodynamic profile.

How about a NACA duct in the belly pan running to the repurposed heater core?

NACA duct - Wikipedia, the free encyclopedia

http://sports.racer.net/tech_info/ae...calculator.xls

Keep the radiator and resize the inlet and outlet.

http://ecomodder.com/forum/showthrea...bums-3541.html
http://ecomodder.com/forum/member-ae...ing-system.jpg

I'm extremely interested in your belly pan idea. Do you have any pictures?

As for aluminum hood scalding... I see it as a cheap way to keep cats and other critters off.

Actually, the more I think about it, the more I like the idea because the hood is commonly replaced with carbon fiber or fiberglass to reduce weight and increase performance.

I wonder if it's possible to have a decent looking aluminum hood fabricated, but I'm scared to ask how much it would cost.

I've never actually made it, so no pictures.

What gains did you experience with a full grill block? How are your temps?

Its very hard to say. I never did ABA testing. Also, I put it on in fall when the temperatures were dropping so it was very hard to tell as my mileage was dropping. The one thing I noticed was a slight hill I go down. In winter I used to slowly loose speed going down it. With the grill block I was able to maintain speed going down it. Also, warm up time was reduced a fair amount.

I believe this is a no go. Vehicle manufacturers have to adhere to certain codes, one of which says that exterior parts of automobiles can not get above a certain temperature. I am sure that pumping 200F+ coolant up near the hood would burn someone that happened to touch your hood. Safety first!

Actually the best way would be to use the radiator to reduce drag. The P51 did this and actually gained thrust from this technique above 300 mph.

two papers on the subject

http://naca.central.cranfield.ac.uk/...rc/rm/2147.pdf


http://naca.central.cranfield.ac.uk/...rc/rm/2302.pdf

What about a black car on a sunny day? And what about the exhaust?

You are really making the idea appealing now. People that touch my hood should have something remind them not to be touching my hood. Scalding temperatures should do the trick. I always liked the look of the unpainted Delorean, so maybe brushed aluminum would give the car character. Anyone know the MPG penalty for a flux capacitor?

Interesting... so I just have to go 300mph and have a jet engine to implement this fuel saving trick. I've got a few mods to make...

Black paint won't scald nearly as badly as aluminum backed by 200+ degree water. It has to do with thermal capacity.

You bring up a good point about exhaust. My motorcycle has a very exposed exhaust that will give an instant 3rd degree burn if you aren't careful. If I ever figure out how to cost effectively implement an aluminum hood, I'm all over it.

no yo don't need a jet, you need something that will expel heat through a radiator. Using this technique you will experience reduced drag at lower speeds and a possibly positive thrust above 300mph if you do it right.

One more paper

http://naca.central.cranfield.ac.uk/...rc/rm/1683.pdf

one thing to remember the Daox hinted at is that the lower drag will reduce the engine load and reduce the amount of work required and reduce the amount of heat dissapation required. Which would make your radiator a bit oversized for the job.

Wow thanks to all your responses and ideas!

I think before I further investigate this, I will go to the extreme and just
tape up the whole front of the car including all the little gaps around the
lights,bumper,grill,hood ONLY for a few comparative high speed coast down tests.

If I can't show any considerable measurable difference going to the extreme,I will not risk overheating with grill blocks. I've done a LOWER grill block on my truck once and it over heated on me which was surprising because I thought
as long as the top grill is open where the real heat is I can't get in trouble...
( WRONG! )

Bicycle Bob hinted about the lack of effectiveness using tubes attached to
aluminum under belly plate etc. Come to think of it on SUVs and vans with
rear a/c and heat,there are these long aluminum lines going from the front to all the way in the rear to the heater and evaporator cores and the manufacturers don't even bother insulating them yet they still function so
that's a pretty good indicator what a tremendous amount of heat is being created by the engine and how good an actual radiator is really that it can handle getting rid of all the excess!

I like the hood idea as well! Could double as a large frying pan too! Go camping,crack a few eggs on the hood...throw a wet T-shirt on it to dry in seconds :)

For those that found the hood as a heatsink idea interesting-

Source

The following is a partial list of manufacturers who use aluminum body panels.

Acura – NSX (all), RL (hood, decklid, fenders and trunk)
Aston Martin – Vanquish (body panels), DB9 (hood)
BMW– Z8 & 7 series (body panels), 6 Series (hood, doors, body panels)
Buick – LeSabre (hood), Park Avenue (hood), Rendezvous (liftgate)
Cadillac – CTS (hood), Deville (hood), Escalade (liftgate), Seville (hood)
Chevrolet – Suburban (liftgate), Tahoe (liftgate), Venture (hood)
Chrysler– Concorde, LHS, Pacifica (hoods)
Ferrari – 360 Modena (body panels)
Ford – Expedition (hood & liftgate), Explorer (hood and fenders), F-150 (hood), Lincoln Navigator (hood & liftgate), Lincoln LS (hood, fender & trunk lid), Ranger (hood), Lincoln Town Car (hood), GT (body panels), Mustang GT (hood)
GM – Yukon, Yukon XL (liftgates)
Honda – S2000 (hood), Insight (body panels)
Infiniti – Q (hood & trunk lid) I (hood & trunk lid)
Jaguar – XJ, S-type (hood)
Lancer – XJ, S-type (hood), Evolution VIII (roof)
Lexus – SC430 (hood)
Lotus – Elise Sport 190 (body panels)
Mercedes – CL500, SL500
Mercury – Mountaineer
Nissan – Altima, Maxima (hoods & trunk lids)
Oldsmobile – Aurora (hood & trunk lid), Silhouette (hood)
Opel – Speedster (body panels)
Panoz – Roadster (body panels)
Peugeot – 407 (hood)
Porsche – Cayenne (hood), 911 (hood)
Plymouth – Prowler (hood, doors & trunk lid)
Pontiac – Bonneville, Montana (hoods)
Range Rover/Land Rover – hoods, doors, side panels
Saab – 9-2X (hood)
Subaru – 9-2X (hood), GT (hood), Legacy (hood, bumpers, sunroof)
Volvo – (hoods & trunk lids)

The Ford Mustang V-6 also has an aluminum hood. It's not limited to the GT. I verified it with a magnet. :)

my idea would be to use the high pressure area at the bottom of the windshield to flow air into a radiator. you would have to do extensive ducting though. but since most of you ecomodders do not have a/c , have it but its broken, or just never use it, then use the louvered area where the climate control system gets its fresh air from. which is the area right under the windshield. since this area is high pressure, you would be foprcing air into ducting and out of the radiator. also since this is a high pressure area and you are relieving the pressure, it might even have an aerodynamic improvment. i would be wrong though. but i know for sure that the area under a windshield is a high air pressure area. why not use some of that pressure to our advantage, instead of squandering it on nothing.

Just make sure not to try this with an old Saturn. The plastic would probably melt :rolleyes: :p

...what about "surface" radiators like those used on the British Supermarine racing seaplanes back in the 1930's? Of course, they might interfer with door openings (wink,wink).

what if you were to use this low drag cooling system and run the duct work all the way back the car and let the air exhaust through the rear bumper. could you get enough air out the back to help reduce the negative pressure back there?

On a sunny day, a car hood can get up close to maximum coolant temperature just parked, so there would not be much left for cooling. A belly pan, OTOH, is safer and cooler but more prone to damage. AFAIR, the 1911 Napier Railton was the first and last surface-rad car, with copper tubes surrounding the engine and leaving only top access for quick service.

Theoretically, one could run a big duct through the car to raise pressure at the back, but the overall effect is to make the car bigger for the same useful volume, with more surface area.

The air pressure at the base of the windshield is generally lower than at the front grille. Leaving it alone is not a waste, unless you use a fan to grab low-pressure air for ventilation elsewhere. There might be a small gain to letting air flow slowly through the interior, since even a rough duct has little drag at low speed.

http://ecomodder.com/forum/member-ae...ing-system.jpg

A) a similar approach to cooling round, reciprocating, air-cooled-cylinders of aircraft engines, through the use of controllable cowl flaps.

B) exactly the same approach was used to cool engine oil on both P-51 and C-69/121 propellor aircraft.