Half Baked Ideas #1: Chassis radiator...

[riddles]

Why not use your idea, but add protection underneath and do it for the whole length of the body creating a duct under the whole car. Could also smooth out the underbody and perhaps have some additional aerodynamic effect.

[Stealer Of Souls]

Why not use your idea, but add protection underneath and do it for the whole length of the body creating a duct under the whole car. Could also smooth out the underbody and perhaps have some additional aerodynamic effect.

You've pretty much hit the nail on the head. After Redmist mentioned bash damage I thought that the answer would be ducting panels on the underside. Smooth air, protection, ducted cooling air flow and style all in one...

I'm still thinking that the comments about torsional movement of the chassis breaking the brazing will rear it's head. I think that this movement will be the second killer of this idea, the first being poor high-load performance

[RedMist]

why not mount it in the boot horizontally, with holes in the bumper and shroud to direct air from under the car, through radiator to the back of the car, win-win situation: increases low pressure under the car, using low pressure behind the car, more room at the front of the car, better weight distribution, increased coolant capacity.

Definitely a possibility. Although the added weight of the extra coolant lines and ducting may reduce the benefits. Also this approach will not benefit the COG, although this may be offset by the improvement in ground effects downforce (I think that's the correct term).
[/quote]

This would certainly be the route I would take. And may actually experiment with in a SW20 once I corner weight it. The effect on COG could be minimal if you placed the rad close on horizontal in the airstream. Definate benefit over a front mount rad as you no longer push air with the rad, the required airflow for heat dissapation is generated by the venturi following the car.

[riddles]

I'm still thinking that the comments about torsional movement of the chassis breaking the brazing will rear it's head. I think that this movement will be the second killer of this idea, the first being poor high-load performance

Ok, so why attach to the underbody just to use it as a heatsink? Why not leave the pipes whole and use brackets to mount them in the midlle of the duct created?

Likely that weight would be increasing with this though where you were wanting to stay weight neutral.

[fj40cruzapete]

speedway super saloons run a radiator in the rear of the car with being a tubeular spaceframe they use the chassis as pipng from the engine to the radiator

[matt dunn]

Do you realise just how much surface area there is in a radiator?
All the little fins that bend etc etc. Get an old one pull it apart and lay it all out on the ground. You'll be amazed.

And how much air flow they need to support decent HP?

Anything with decent power would require more surface area than the floor of the car.

Nice try, but I would not think so.

But hey, someone's gotta try it to find out.

Matt

[Stealer Of Souls]

I'm still thinking that the comments about torsional movement of the chassis breaking the brazing will rear it's head. I think that this movement will be the second killer of this idea, the first being poor high-load performance

Ok, so why attach to the underbody just to use it as a heatsink? Why not leave the pipes whole and use brackets to mount them in the midlle of the duct created?
Likely that weight would be increasing with this though where you were wanting to stay weight neutral.

Yeah. The thought was that piping alone would lose a whole lot of surface area (as mentioned by Matt). So yeah, but attaching it to the floor pan you could use the chassis as a big heat sink, and hopefully regain a little of that lost surface area. If the heat propagated nicely through the steel then you could actually regain a reasonable portion of the surface area. It still wouldn't compare to the original radiator, but again, if the heat propagated nicely you get to a really large thermal mass.

Do you realise just how much surface area there is in a radiator?
All the little fins that bend etc etc. Get an old one pull it apart and lay it all out on the ground. You'll be amazed.
And how much air flow they need to support decent HP?
Anything with decent power would require more surface area than the floor of the car.
Nice try, but I would not think so.
But hey, someone's gotta try it to find out.

That's my thoughts too. I would expect that this idea would fail to perform under high load situations...
But in saying that, the average car cooling system is oversized for NZ conditions. Okay, that comment will get some flak, but just try this. Take your thermostat out and go mad. At stand still with just the rad fans you'll find that without the restriction and control of the thermostat a standardish engine will struggle to overheat, and when moving under low load (cruising) the engine will struggle to stay at normal operating temp.
This is what makes me think that for relatively normal driving it MAY work. It may even work for relatively short times at high load. At least until the chassis starts to get really warm.

[sergei]

BTW Steel is not very good heat conductor (it is actually really poor compare to aluminum alloy or copper), so it will not remove efficiently heat away from copper piping, copper piping are not the lightest either, counting the mass added by copper piping/lead-tin brazing (lead and tin are very heavy, and with network of pipes it will add a lot of mass), also brazing is very prone to cracking from vibration/thermal stress. My option of mounting radiator in the boot, would be lighter choise.

[Stealer Of Souls]

The original method called for measuring the system mass to get roughly identical masses between copper piping (plus fluid) and original radiator (plus fluid).
So there should be little or no increase in system weight.

Steel is comparatively a poorer conductor...
But on an absolute scale it is still quite a reasonable conductor.
(All using the same scale (Watts per meter kelvin) approx values are,
al~180
cu~400
concrete~1
steel~60
polystyrene~.03
iron~40
gold~300
glass~1.4
air~26
engine oil~145
radiator fluid~250
R12 freon~72).
Not saying that the floorpan is an ideal heat transfer medium. But it offers a very large thermal mass that wasn't originally built into the system - the mass of the copper piping plus fluid is approximately the same mass as the OEM radiator + fluid, the piping is split and spread over as greater area as possible to increase fluid contact area with floorpan to try and counteract the steels lower conductivity.