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Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

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Old 04-08-2009, 12:22 PM   #171
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I'd like to reiterate that it would differ from car to car. This guy says that there are too many variables to make a blanket statement:
http://ecomodder.com/forum/22460-post6.html
Quote:
True, warm air will cause ignition retardation. In some engines this will happen faster than the benefit from the increased load (and reduction of pumping losses). In other engines it will happen slower than the benefit from increased load and you will see benefits from it. It may work great on some engines during the winter, but since ideal intake temps, for example, are around say 80?F the benefit is negated during summer. The point is there are too many variables to have a blanket statement that says they do or don't work.
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Old 04-08-2009, 12:25 PM   #172
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The compression "ratio" of any engine is calculated by the volume of air displaced by the pistons from BDC to TDC. This volume is compressed into the area of the combustion chamber that is left over as well as the small area above the top ring. That total volume is also changed by any positive or negative volume due to differences in the top of the piston. Domed pistons reduce the combined unswept area, while dished or notched pistons increase the non swept area.

Warmer incoming air is less dense than cold air. The difference is density is 20% from ambient temperatures of 32 F to 200 F. Intercoolers increase the density by removing some of the heat from the intake charge.

Effective compression is the true compression created in any engine. Warmer air being less dense recieves less fuel than cooler air.

Nova noticed the lower peak power when he tried WAI, and didn't like that fact. With WAI you create lower effective compression, due to less dense air.
Less dense air allows the timing to be advanced more than cooler more dense air because the effective compression is lower, even at WOT. This is clearly demonstrated by the winter-summer power difference in any car without WAI.

Any time you compress air, whether it is in an engine, or a compressor, you are packing the latent heat energy in the air into a much smaller area. The heat content of that air is measured in Kelvin, not farenheit or centigrade. At a low enough kelvin temperature for air it becomes a solid, slightly higher it becomes a liquid, and higher than that it becomes a gas.

The expansion of air in its gaseous state, above its kelvin liquid temperature is the only state where it can "atomize" fuel. The lower the ambient temperature the lower the temperature of the "effective" compressed mixture.

Gasoline also has a freezing point, at which it will no longer atomize into a vapor.

As ambient temperatures drop it requires more fuel to initiate a cold start. In diesels as temperatures become extreemely cold you must mix gasoline with the diesel fuel or preheat the engine and fuel to achieve cold starts. As temperatuires drop to the coldest extreemes on the planet, no internal combustion engine will start unless the fuel and air are preheated.

Sometimes its easier to understand a physical principle by carrying it to its extreemes. Any engine will start easily with little fuel enrichment in thehottest places on the planet. In the coldest places it requires preheating to get decent enough atomization for initial combustion to occur.

While hot intake air alone would cause preignition, without any spark control, that is not the case in modern engines. The first fuel injected Z cars in 1975 had problems with vapor lock. The intake manifold was directly above the exhaust manifold and the radiant heat in the cast rion exhaust manifold would boil the fuel in the injectors. Nissan added a thermostatically controlled cooling fan that blew air on the intake manifold and injectors to prevent this.

Another solution would have been to install a tubing header, because the heat retention of the tubing header was only a fraction of the heat retention of a heavy cast iron manifold.

Most manufacturers avoided this becasue the headers tended to blow gaskets soon enough to cause warrantee claims, but the aftermarket flourished with header installations to eliminate the "vapor lock" in the Z cars from 75-78 before injector cooling fans became standard equipment.

regards
gary
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Old 04-08-2009, 12:40 PM   #173
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jay,

so the vacuum holds the door closed and the thermostat opens and closes (varies) in order to keep the air temp at a predetermined temp. I like that. it really is the best of both worlds.

you could further heighten the affects if you could change the thermostat in order to increase the temps more but then you would have to retune the carb for that. I saw a buddy of mine do that to his chevette. it was not a fun experience. he plans on fuel injecting it soon so he didn't put a lot of effort into it.
Yes, there is a vacuum actuated thermostat mounted inside the air cleaner assembly. It allows vacuum to pass when the temp is cool, and shuts off the vacuum when it gets too warm. When operating properly it should cycle the damper open & closed to regulate a somewhat constant temperature.

-Jay
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Old 04-08-2009, 12:43 PM   #174
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Following the WAI links in NovaResource's sig:

In this link:
http://www.gassavers.org/showthread.php?t=396
MetroMPG fails to produce any measurable effect (no increase or decrease in FE) from a WAI, but continues to support the concept.

One of the links leads to this:
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The results are in from the warm-air intake...31.1 mpg, which is a huge improvement over 26. To keep the test scientific, I didn't modify my driving style, hit redline a few times and even had 2 passengers during one trip. My cruising speed on the highway was 70. The datalogger shows the difference -- Long-Term fuel trim went into the negative percentages with the increase in intake air temp (leaner mix, less fuel).

The setup draws air from the "Y" at the exhaust manifold using a clothes-dryer duct, into the airbox. Temps ranged anywhere from 90-150F.

So, with the understanding that air is a poor conductor of heat, I'd like to tap into the coolant line with a heater core closer to the intake point, to maximize the effect. Thanks!

-RH77
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Old 04-08-2009, 12:46 PM   #175
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my head hurts....

make it stop.....

too much data.....
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Old 04-08-2009, 12:53 PM   #176
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Lets use some reverse logic.

Name any car that gets better mileage in winter, regardless of cold starts. That factor can be easily eliminated by mileages recorded on long trips where there are no cold starts to provide any effect.

Take an eye dropper with gasoline and drop gas onto a pan when its freezing. Put the pan in your freezer. The stick the same pan out in the sun and let it get hot and see how long it takes for the same drop to evaporate.

One of the key components of the research into Homogenous Charge Compression Ignition is to preheat the fuel and provide turbulence to enhance the atomization at the milecular level. When achieved HCCI eliminates preignition altogether by creating simulatneous ignition of the fuel air mix in every part of the combustion chamber.

Another result of successful HCCI is the potential of eliminating the post combustion treatment of exhaust gasses altogether.

Also a 25% improvement in mileage.

Higher compression, higher intake temperatures, Ignition timing becomes irelevant since combustion is created by compression alone. Diesel fuel economy in a gasoline engine.

regards
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Old 04-08-2009, 01:28 PM   #177
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One of the key components of the research into Homogenous Charge Compression Ignition is to preheat the fuel and provide turbulence to enhance the atomization at the milecular level. When achieved HCCI eliminates preignition altogether by creating simulatneous ignition of the fuel air mix in every part of the combustion chamber.

Another result of successful HCCI is the potential of eliminating the post combustion treatment of exhaust gasses altogether.
An HCCI engine and an otto-cycle engine and not the same. Apples...oranges.
Second, the HCCI engine heats the fuel, not the air. Again, Apples...oranges.
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Old 04-08-2009, 01:44 PM   #178
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of everything said (especially by the cow) that was your response.

I guess you are right. the HAI will never work, at least not on anything you own.

just WOW
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Old 04-08-2009, 01:59 PM   #179
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of everything said (especially by the cow) that was your response.
You want me to reply to everything? I was just replying to the last post.

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I guess you are right. the HAI will never work, at least not on anything you own.
You are correct, an HAI will not work.
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Old 04-08-2009, 04:24 PM   #180
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Yo Nova, and what cycle is HCCI?

regards
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