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Well, in physics class we are studying the second law of thermodynamics where no heat engine can be 100% efficient. As i always do i asked how efficient automobiles are and the teacher said about 20% if i remember correctly. My question is: Can we tweak out our engines so that we can make them more efficient without letting them melt? This is probably for anyone into physics. Any input would be nice thanks
 

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this is why more engines are being built with aluminum blocks and heads

there are problems with making engines more efficient, the biggest being cost..look at the prices of electric cars, all that good research and design is passed on to the consumer through the high sticker price
 

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The high sticker price isn't even what it really costs, the government (or someone) absorbs some of the cost, and electric car like the Insight or Prius should have an MSRP of $60,000

This info from David Suzuki
 

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I do remember this from way back when in college! The gasoline engine is an effecient pig, that's about it. However Super or Turbo chargers can raise the efficiency of an engine considerably. (especially a turbocharger) I can't recall how much better a turbo engine is, ask your professor that one. Let us know what they say.
 

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turbocharging (or supercharging depening on the means of pumping air) will increase the volumetric efficiency of the engine. A naturally aspirated 4 cycle engine is generaly around .75-.85 and a turbo charged engine is around 1.0 This means a 37%-41% increase in horsepower along with an increase in torque. However "efficiency" is a bulls**t word since it all depends on what you are trying to accomplish or prove. If you want increased fuel economy then that is obtained on a slow-speed turbocharged engine with aftercooling as compared to a high-speed engine.
 

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Gasoline engines are very inefficient. What saves them is the energy density of gas. The largest unused and non-useful byproduct of a gasoline engine is heat. If you can reduce the amount of excess heat the engine produces you will have a more efficient engine. The cooling system is entirely parasitic, it does nothing to produce hp and in fact takes a fair amount of hp to run. The leftover heat going out of your exhaust system, wasted power. You can increase the volumetric efficiency, which raises horsepower, but this also uses more fuel (14.7:1 ratio remains the same) and produces more heat, thus wasting more potential energy. This is the reason for the experimental ceramic engine components-excellent thermal resistance, keeping the heat in the combustion chamber rather than soaking into the block.
whodat
 

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I heard about engine's mostly made of ceramics, but don't they cost a heck of a lot of money?
 

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Take a thermodynamics course, more of your questions can be answered by studying the Otto cycle. I believe that the thermal efficiency of a normal automoblie engine is 18%. There are many ways to increase the thermal efficiency of the engine. I had to study them, you should too, so I won't give you them all. :D
 

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basiccly what it all comes down to is keeping the engine cool with having a better then average hp rating. Intercoolers come in a big part of this as well and as most of you know they will also increase hp. so in other words slap an intercooler and some kind of turbo/ramair type deal and bam you get a more efficant engine.
 
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