Quote:
Originally Posted by NovaResource
I totally agree and I go one step further: oil temps. Keeping the engine warm (coolant and oil) is the most efficient.
Yes, a warm engine, but not warm intake air.
Yes, more air means more fuel for more power but that also means less throttle opening to produce the same power. Smaller throttle openings means less air flow means less fuel added. Also, the cooler the intake air, the more ignition advance you get. The earlier you ignite the fuel the more complete burn you get. Warm air means risk of detonation so the ignition is retarded. Retarded ignition means less burn time and more fuel wasted.
Warm Air Intakes do not create better mileage. Read the test proof:
http://www.metrompg.com/posts/wai-test.htm
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Greater density means more fuel. Hot air is less dense, so you need to make sure you use the term density instead of more. I can feed 20% more volume of air into an engine if it is at 200 degrees as I can at 32 degrees and its the same mass (weight) of air.
We all should understand that the smaller engine working at a greater load is more efficient. If I could reduce the engine size by changing the displacement so it would operate at cruising speeds with no manifold vacuum, then I get the greatest effective compression and the highest efficiency.
The problem arises when I need more power to climb a hill or merge onto an interstate, but how many times in a 1000 mile trip do you actually floor the gas pedal. So we design cars for the extremes and lose any chance for real mileage. Now if you could add a supplemental power source for the extremes you could have twice the gas mileage.
WAI is a method of effectively reducing the displacement of a conventional engine, while increasing the effective compression and thus increasing the efficiency. For mr in thousands of miles off real world experience it is worth at least 10% in mileage. Whether it works or not in every car I certainly can't say, but in my case it has worked with every car I have driven that I could change the intake system. On my VX it was simple, I reversed the intak air snorkel so it was pulling air right at the top radiator hose and the top tank of the radiator.
The old Packards had the thermostatically operated louvres in the radiator that controlled air flow to the radiator. Tractor trailers have adjustable tarps with zippers that allow them to reduce the airlflow over the radiator, which also serves to increase the intake air temperature. they do this because it works, and reduces their fuel cost, guaranteed. Hot air allows the fuel to atomize better and results in more complete combustion. Perfect atomization of the fuel would increase engine efficiency by 25%. Check out homogenous charge compression ignition, which is when you can use compression only to ignite gasoline, like a diesel running on gasoline.
Honda designed a lean burn engine to run on regular gasoline at air-fuel ratios of 22 to 1 and higher. No preignition, just a very turbulent air intake strategy that allowed better atomization.
The old preheated carburetors gave way to injectors that sprayed a very fine mist of fuel directly on the head of the intake valve, which helped with atomization as well as cooling the valve.
New direct injection systems are now operating at pressures above 20,000 psi at the injectors which improves atomization, and the next step is HCCI (homogenous charge compression ignition) which is controlled detonation or "spark knock". There is no problem because the air-fuel mixture is truly perfectly distributed so the instant conbustion occurs it happens everywhere in the combustion chamber, instead of originating in separate points and colliding somewhere in the combustion chamber.
All of these things are coming, but no matter what they do they will not make an engine run better at 40 below than it does at 90 above. By better I mean more mileage, not more power.
In most cases more power does not mean more efficiency. Hondas most efficient gasoline engine is not a 4 valve per cylinder design. Instead it si a two valve twin plug design with a very high swirl in the combustion chamber to maximise the consistency of the mixture.
regards
gary