Quote:
Originally Posted by NovaResource
The time a WAI will help fuel economy is in colder weather while the engine is warming up. But it's not because the engine is getting warm air instead of cold air, it's because the engine is getting up to operation temp quicker. Once the car is up to operating temp the WAI is no longer helping. The fuel savings is not from a WAI but from a engine that gets up to operating temp sooner. This is why test results show little improvement and vary greatly with different cars. A car that warms up quickly on it's own will show little improvement with a WAI but a car that takes a long time to warm up normally will show greater improvement with a WAI.
This is the reason why older carbureted cars of the 70's and 80's had factory installed, vacuum controlled warm air systems. When the engine was cold, a flap in the air cleaner lid closed to block the cold air inlet and pull air in off the outside of the exhaust manifolds. As the engine warmed the valve would open to allow in colder air and block of the hot air. Another reason for this is that carbureted engines don't atomize the fuel that well. The hotter air helped with fuel atomization however, this is not a problem in modern cars with fuel injection.
The flap operated whether the car was cold or warm. When it malfunctioned you could get killed trying to cross a street, the hesitation is something younger drivers have never experienced. Fuel mileage dropped 50%, plugs black.
It didn't work cold, because there was no heat to warm anything up The choke was used for that. Some cars had passageways that allowed hot exhaust gases to pass through the intake manifold (1937 Ford). The Chrysler slant sixes had a exhaust manifold junction right under the carburetor to warn things up.
Warm or cold----facts backed by real evidence.
Again, best fuel economy comes from a fully warmed up engine (warm coolant and warm oil), not warm intake air. You want a good idea for better economy? Install an intake system that pulls in warm air during startup when the engine is below operating temp but switches to cold air when the engine is fully warm. Another good idea: install an engine block heater and an oil pan heater to keep the coolant and oil temp warm when the engine is not running.
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Lets see, by your statement you have concluded that there is no difference between a warm engine at 20 below and a warm engine at 100 degrees as far as fuel economy. I would like to see you provide a shred of proof of that statement, or are the temperature extremes too great.
The imperfections of modern fuel injection are clearly demonstrated by the efforts of manufacturers to achieve Homogenous Charge Compression Ignition in gasoline engines. Homogenous Charge means the fuel and air mixture is truly evenly distrubuted in the combustion chamber. That same mixture is ignited by compression alone without any spark whatsoever. The result is a 25% improvement in economy as well as the elimination of the catalytic converter with virtually zero regulated emissions.
Why would manufactirers spend tons of money to improve a system if your statement about it being perfect was true? The fact is the present systems look much better when compared to the old carburetor types, however there is still a massive potential for improvement.
Google HCCI if you really want to learn that there is much room for improvement over the present system that you describe as perfect. By perfect you imply that there is no room for improvement in fuel distribution because modern engines are fuel injected. HCCI proves without any doubt that modern systems are far from perfect.
The attached photo is my mileage from my trip yesterday. 65 MPG for 355.5 miles. Almost all of it was highway. The EPA highway rating for my car is 50 MPG. My modifications are a 40% grille block and 44 PSI air in the tires. Temperatures ranged from just above freezing to 65 degrees. Driving was from eastern Virginia to Blacksburg Virginia with elevation changes of 2000 feet. The grille block also retains heat in the engine compartment that increases the air temp to the intake system on the engine.
How much of the improvement was driving style, grille block, or tire pressure, or warm air would be difficult to distinguish, but the net overall improvement is 30%. Also consider that that is on 10% ethanol fuel which has a lower energy content than non ethanol fuel.
Also notice the fule guage is reading half a tank. That is a 10.5 gallon tank.
regards
gary
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