does any body know how much waste heat a typical engine produces? i'd say there's probably enough to make some use of.

how about a stirling cycle powered super charger? it won't work 'til your cars warmed up, but you generally don't want to make use of a supercharger (or turbo, or noz for that matter) until your engine is warm anyway, 'cos your engine'll end up dying young.

if i'm honest though, i'm not convinced that this can produce quite the power you need, on its own. an improvement would be to use the stirling engine, to run a compressor. you can save to air for when you need it.

i know having a tank of compressed air, a stirling angine and a compressor can be quite weighty, but i still think the extra power will be more than worth it. besides, you don't even need to use the air to gain power. you could use it for better efficiency. if there's any carbon monoxide (or worse still, unburnt fuel) coming out of your exhaust, then your not buring your fuel efficiently. this might be because you combustion chamber isn't efficient, but it might also be because you're not getting enough air into the cylinder heads. if you have an efficient combustion chamber with poor air flow (like a hemi) then you could use the compressed air, without any more fuel, to increase effieciency.

a stirling cycle engine can be a little more than 80% efficient. if anybody knows what percentage of the engergy produced by a car engine is heat, then we can get an idea of how useful this would be.
-- seanbo, Dec 19 2004

I thought 75% of an ICE is converted to heat.
-- mensmaximus, Dec 19 2004


From the American Stirling Company web-site...

"Q: Could a good Stirling engine be built by starting with a small-block Chevy V8, or perhaps an air compressor, and converting it to a Stirling?

A: This has been tried many times by many different people and the conclusion is that it really doesn't help all that much. In his book Making Stirling Engines, Andy Ross describes converting an automobile freon compressor to a Stirling engine. The conclusion of Andy and others is that while this approach can be made to work, there are too many compromises when you start with some parts that were made for some other use. You might as well build the entire machine as a purpose built Stirling engine."
-- ato_de, Dec 20 2004


If you use a hybrid ICE electric system, you could use a stirling engine to convert wasted heat from the cooling and exhust into additional electricity by powering a second generator.

If you can get 30% efficiency from the stirling engine and 30% efficiency from the ICE engine overall you get 51%. If the efficiency of the stirling engine goes up to 80% the overall efficiency goes up to 86% and you still get the instant responce to power demands from the ICE engine.
-- Belfry, Dec 20 2004


mensmaximus - it's that inefficient? wow, that's worse than a light bulb. there should be pleanty of power for the compressor though.

ato_de - i'm not converting the engine, and adding one. i'd never want to power the wheels from a stirling engine.

Belfry - there's also a loss of efficiency in converting kinetic energy from the stirling engine into electrical energy. you're right though, i think making use of several waste energies would lead to a highly efficient engine. i'd be worried about the weight, and number of things that could go wrong though. plus, i don't really like the current crop of ic/electric hybrids - non of them are as efficient as the diesel vw lupo. perhaps using a stirling engine in this way would be useful for a deisel electricity generator - the kind you get on building sites.
-- seanbo, Dec 20 2004



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