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Originally Posted by LostCause
First, take a small atkinson cycle engine - 13:1 CR with an effective 8:1 CR. Use a small, efficient turbo ducted through an intercooler to raise the effective CR to ~10:1 (i.e. miller cycle). Use variable valve timing to increase the CR to 13:1 w/ turbo (which should already be operating in its most efficient range) and switch the injectors over to feed from a smaller tank holding 91 - 100 (avgas?) octane fuel during acceleration. Route the spent gasses through the primary turbo and feed the residual gas into a turbocompound that sends power back into the flywheel.
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I don't mean to quote myself, but this will put my response into context. I always think it's cool when some of the crazy ideas I think up get validated by a legitimate group. I suppose it's because it's the logical conclusion to a problem, but at least I don't feel like a total crackpot dreamer...
Anyways, I stumbled upon
this. MIT developed a small turbocharged engine that uses direct-injection of ethanol for acceleration to combat detonation in a normal SI engine. 1 gallon of ethanol supposedly lasts 100 gallons of gasoline. While it's not 100LL, it is the same concept. No mention of the VTEC Miller Cycle though,
.
BTW, the same thing happened with BMW's steam cycle using waste heat. I figured why not use the already hot coolant, super heat a portion of it, inject it into cylinders or an integrated steam engine (like Honda's IMA). Free energy for a little complexity, woo hoo.
Another idea is evaporative cooling. An old 1930's concept of using the latent heat of water to cool an engine. Pressurized water (coolant runs at ~5psi right now I believe, but this would need more) is heated well above boiling and evacuated into a tube at atmospheric pressure. Liquid water --> steam sucks up tons of energy in itself and steam has a lower specific heat capacity. I remember seeing this online for cars somewhere, the idea being to lower the cooling system weight and drag...
Sexy...
Hmm, now what about my flying robot ninja idea...or training galapagos turtles as a form of alternative transportation...yeah...
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Originally Posted by diesel_john
Would higher intake temp. on a diesel be like reducing the compression ratio?
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Compression ratio is a geometric quality determined by initial and final cylinder volume. A higher intake temp would kill power as it would be less dense. Less air = less fuel = less power. Higher temps would serve to evaporate fuel and encourage complete combustion, but you gets tons of NOx (chemical smog + major greenhouse gas) and you
could, although unlikely, run into metallurgical issues w/ exhaust valves overheating.
- LostCause