Thermodynamics experts... what do you think of this idea?
 

A large portion of the engergy in the fuel of an internal combustion engine gets dumped out the tailpipe in the form of heat energy. Another large portion, particularly in part throttle conditions, is consumed in overcoming pumping losses.

My idea: use some type of large capacity heat exchanger to use exhaust (and/or cooling system) heat to significantly pre-heat the engine's intake air during part throttle operation.

A hotter intake charge would occupy much greater volume for a given mass of air. Since more volume is needed in order to get the same mass, a much larger throttle opening will be required (compared to the same engine without this system), resulting in much less maifold vacuum and therefore reduced pumping losses.

Additionally, the higher air temperature will ensure that the fuel is completely vaporized before it ever reaches the combustion chamber.

A bypass valve would allow cool air into the intake whenever more power is needed for acceleration.


... so how does that sound?

https://www.ford-trucks.com/forums/s...d.php?t=401695

http://schou.dk/hvce/?mode=2

Dang, I thought I thought of it first! Haha

Hehe. It is an interesting concept :-X22

The problem with this idea is that a engine gets its power from expanding gasses and by inducing hot air there would be a less dense mixture and less power produced and a even bigger problem would be detination because as the tempature of the compresed mixture increases, so does the octane requirement and not even 93 octane would be enough. GM played with a engine in the late 70 and early 80's that was a V8 that used 4 cylinders to burn fresh mixtures and then it went to 4 other cylinders (paired with each one) to further expand the gas and get a little more energy out of the gas too. Their main reason was to reduce emissions and not increase MPG. It ran but the output was reduced (no surprize) so they abandoned it after a while. The best way to increase efficency overall is to raise CR and use only 93 octane fuel because if CR's of 11 to 1 or so were used the engine would gain about 8 to 10% more MPG an usable power per gallon of gas but given the consummers love affair with 87 octane, this is not likely to happen (even though 87 is hurting their performance and MPG now on new vehicles as the only reason engine have knock sensors if to limit complaints about running on 87 octane and to give the illusion that engine is happy with it.

The most common way to extract wasted heat energy from the exhaust is a turbocharger. An interesting variation on that was called Turbocompound, used on the Curtiss-Wright R-3350 aircraft engine in the 1950's (DC-7 and Super Constellation). It had a turbine, just like a turbocharger, but the output was used directly as added power to the crankshaft.

Jim

I think some 4360's did too. (Those engine were real beasts with 28 cylinders)

Only the 3350's had Turbocompound, allowing Scanivavian to fly Connies from Stockholm to San Francisco nonstop. How would you like to have done a "tuneup" on a B-36 bomber on a SAC base in Alaska in winter? Six 4360's times two plugs per cylinder times 28 cylinders = 336 spark plugs, yikes!

Jim