From: www.ananova.com/news/story/sm_834766.html?menu=new...s
"Wrapping car engines in plastic could help cut fuel bills, new research has shown.
Engineers in Germany have found locking heat inside the engine can greatly improve performance.
The findings could lead to engines being completely clad in blocks of expanded plastic foam, The Engineer magazine reports.
By reducing heat loss, plastic wraps could theoretically cut fuel consumption by 5% in the summer and up to 10% in the winter.
The system has been tested at the Cologne University of Applied Sciences using a 1.4 litre Volkswagen Golf.
A research team led by Professor Norbert Deuben enclosed the car's engine with 30mm thick polyurethane foam boards. The engine was run to its operating temperature of about 100C before being turned off.
Although the exhaust gas temperature quickly dropped from almost 500C to the level of the surroundings, the engine block cooled much more slowly.
After about 15 hours it had only dropped to around 50C. Without insulation, it would have taken about two hours to reach this level."
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I wonder how much extra strain this would place on the cooling system in traffic jams? The engine must radiate a lot of heat, and where would cats sit if bonnets became cold from insulating the engine?
Sure, it makes sense to keep the engine block warm as it will be nearer the optimum operation temperture.
I was surprised how hot it was inside the bonnet of my C5 HDI a fair while after stopping, it has an undertray and bonnet soundproofing.
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Actually, C5, I should think relatively little heat radiates from the block compared with that lost through the cooling system and exhaust. Surely it will be hot under your bonnet mainly because of the wind blown through the rad, which has to go somewhere?
Insulating the whole block could save quite a bit of petrol if it stayed significantly warm overnight?
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Can't understand why they don't use something more flexible and less flammable - like wool! Available in slabs from www.secondnatureuk.com/press.htm. :)
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Once the thermostat closes, the only way for heat to be lost from the block is by radiation/conduction. (I think)
If my diesel engine started at 50 degrees after a nights rest, then the cabin would be warmer much quicker!
The biggest problem would be where to put the insulation? The majority of modern cars have very little space, that could be why the test was done on a 1.4 Golf rather than a 1.9TDI.
Manufacturers are looking at high-tech ways of saving fuel, surely insulation could have been overlooked?
Ben
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I assume it ould be a layer of expanded foam like you see coating a modern hot water cylinder?
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Hot water cylinders only reach a maximum temp below 100 degrees, engines however are significantly warmer. Oil gets to well over 100 degrees, other bits get far hotter.
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Ben, some good points there, but I can assure you that engine insulation has not been overlooked ...
Before I retired I wrote up and filed a Perkins Engines patent application (GB2364551A filed June 2000) for an encapsulated cylinder block. This consisted of a strong but open framework which was encapsulated in a rigid-setting and high-tech plastic foam.
The foam acted as an outer cover to retain the engine fluids, with mountings provided through it for carrying the external components. The envisaged benefits included economic production, reduced noise emission, better fuel efficiency, faster warm-up and reduced weight.
The patent also described how the same structural process could be applied to transmission units, e.g. gearboxes.
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I just want to clarify that I only wrote-up the invention, I wasn't the inventor. He is a development engineer by the name of Howard Lawrence and he is able to combine lateral thinking with logic, a rare and useful ability.
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It's not going to make them any easier to work on though, is it? Why not just pump the coolant into a big Thermos and then pump it back when you next start up?
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