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In the spring of 2006 when I drove to Detroit Ryan Waddington at Next Energy said that development was at 78% and the threshold for a breakthrough was 80% regeneration efficiency.
The most basic flaw in the EPA design was running the pump at prop shaft speed, which kills the efficiency at higher sustained speeds, while running the pump at wheel speed as is done in the INNAS design eliminates high RPM pump operation.
Back to engines and my belief that they can reach 60% efficiency.
No one has discussed the cooling system, which is a one size fits all configuration. While some here are advocates and some opponents, blocking the air flow through the radiator reduces heat dissipation in cold climates.
Make that automatic with a dual thermostat radiator where coolant bypass the radiator to maintain a constant (and higher) coolant temperature of the coolant reentering the engine.
Engines run more efficiently at higher operating temperatures. The coolant exiting a radiator at temps below freezing can be 75 degrees colder than the same coolant in mid summer.
I have read of claims of 10% improvement in mileage. In extreme climates a hypermiled car can keep the engine cool using only the heater core. The radiator and cooling system need to be able to cool the engine but a "same size fits all" radiator cools to much in 95% of the driving conditions.
Having followed engine design for 4 decades, I have seen many new designs and configurations that seem to hold promise. Has anyone here actually seen a thorough breakdown of the losses attributed to individual systems?
Neil I did look over your proposed design in the first few posts. I believe one of the disadvantages of engines that have opposed cylinders like the old air cooled VW was that I have not seen one of that design that was terribly efficient in the first place.
I think disc type valves are an improvement over poppets in theory, but I am not sure if they have the ability to last and be low maintenance.
Every car manufacturers nightmare is to build some significant departure from their proven designs, only to find out that they have made a huge mistake when some poor design characteristic makes them the target of lawsuits and could possibly bankrupt their business.
Autoteach. I liked the Aprilla design, and my original thoughts were in the direction of Orbital and injecting air and fuel into the cylinder with ports for exhaust. It seems like a significant amount of EGR (Like Edison did in the X prize) may be a solution, to the point of even controlling engine power levels through the amount of EGR applied. At this point EGR is a necessary evil, but I also believe in the future, with the computational ability available today that HCCI will become practical with combinations of ultra high pressure multiple sequential injections during the combustion stroke.
I always felt, from the beginning when they started hanging pollution components on old engine designs, that the real solution was to fix the engines design deficiencies instead of adding stuff to solve the problem. Nissan and Honda tried to do that with fuel injection in 1976 for Nissan, and stratified charge engines in the Honda CVCC civics and Accords about the same time.
The 1977 Accord I rebuilt for Pop was a heck of a nice car. He drove it up and down US1 in the Florida Keys and averaged 40 MPG, and that stretch of road is one of the worst anywhere for efficient driving. The Accord weighed almost exactly the same as my VX and had the same size engine.
Both the Nissan and Hondas in 77-80 time frames did not need catalytic converters to pass emissions because they tried to make the engines inherently cleaner. WE may see that happen again when the true capability of precision ultra high pressure, sequential injections, while combustion is occurring, becomes perfected, which will go far to mitigate the poor leverage referred to in Neil's first posts.
I am not sure that you really need any more than two valves. Honda's ISDI engine uses only two, but the are not directly opposing each other and Honda uses two spark plugs to create good efficiency. They claim it is the equivalent of the old VX lean burn engine without the NOX issues that killed lean burn designs.
If you consider the engine only and use a systematic approach I think the can get close to 60% if you consider development as open ended with no time limitations.
It will require:
Fuel improvements
Variable compression
Multi point and multi sequence fuel injection with fuel heated to a super critical state
Low speed engine operation at only best BSFC rates
Possible some reconsidering of many of the performance improvements that have become common recently (as in the Honda ISDI design which seems to revert to a 2 valve configuration)
I like electric supercharging because it can be configured as a system that does not require constantly driven components like supercharging or turbocharging.
The reason I like the electric supercharging option is because you can significantly downsize the engine, with increased efficiency, while having the very low percentage burst of power available for the very small percentage of time you may actually need that power.
When you drive a car with a instant fuel economy bar graph (mine is factory) you learn a lot about what the cost of acceleration is in fuel consumption.
There are 5 states of operation in a car, acceleration, deceleration, coasting, braking, and idling.
Hypermilers gain mileage by accelerating at peak BSFC, coasting is done with engine off to achieve best mileage. The other 3 are where most of the energy is wasted, and while they are not specifically improvements to the engine, their elimination is a crucial factor in increasing fuel economy.
Also Neil my post 116 just before your request to stay on topic in 117 clearly stated that it has to be a systematic approach. Engine efficiency improvements must be tailored to the power train that is applying the engines power to the wheels, and specific development pathways will evolve when the power train issues are resolved. EPA stated in 2005 that an 80% improvement can be obtained through power train alone. Engine refinements could increase that figures by another 40% to a total of 120%.
A lot of work has been done with engines and they are a greater source of focus, while the real key is a power train that takes advantage of any improvement.
I think if you consider the engine as only running to add energy to the system, and is not designed for drag racing versus fuel economy you will see much resistance from the performance enthusiasts. I once was one of those who wanted power over economy, now I want some power, but would gladly sacrifice that for extreme economy and that may be a difficult prejudice to overcome.
regards
Mech
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