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Old 03-24-2009, 05:37 AM   #91
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Originally Posted by R.I.D.E. View Post
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.
An engine at operating temperature (coolant and oil temps) will create the same MPH regardless of the intake air temps (within reason). Too hot and detonation will happen. That means, the engine coolant and oil are the same temps regardless of weather temps.

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Originally Posted by R.I.D.E. View Post
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.
HCCI is TOTALLY different than an Otto-Cycle engine. HCCI is basically a gasoline-fueled diesel engine. The last thing you want in an Otto-Cycle engine is pre-ignition, but that's exactly what you what from an HCCI. Apples...oranges

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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.
The grille block does 2 things. It maintains the engine coolant and oil temps but it also makes the car more aerodynamic by keeping air from entering the engine compartment. That along will make the car more fuel efficient. Like I said, if the engine temps are the same (20-deg or 100-deg) the engine should get similar fuel economy regardless of intake air temp.
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Old 03-24-2009, 06:13 AM   #92
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Do you really believe that a WAI increases fuel economy my 10.1 mpg? Get real. If that was true, every car made today would have on from the factory. But they don't.
That's because you sacrifice max power to get that advantage. As I pointed out before, a much better approach if starting from scratch is to designate a smaller engine if you have power to spare.
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Old 03-24-2009, 06:23 AM   #93
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HCCI proves without any doubt that modern systems are far from perfect.
Careful you don't go too far with that (and I'm not implying you are). HCCI gains from increased compression ratios, not just improved combustion (yeah, yeah, and other stuff too like potentially lower throttling losses). Since the gains from increasing the standard compression ratios seen in normal spark ignition engines is pretty significant (the curve is still pretty steep at that point), this is probably most of it.
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Main Entry: co de pen dence - see codependency
co de pen den cy
Pronunciation: \kō-di-ˈpen-dən(t)-sē\
Function: noun
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: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
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Old 03-24-2009, 06:25 AM   #94
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I'm saying that in that particular vehicle it works. 10 MPG is well beyond any conceivable margin of error for this test. I would agree that more testing needs to be done, but I don't buy the "Every car would have it already" argument. I can tell you that 2 of my 3 vehicles that I own have it setup from the factory. Manufacturers aren't solely concerned about mileage. They have to make sure the car passes emissions, and has good power. High HP numbers sell cars. WAI/HAI lowers these numbers. Yea, an affordable car can be made that gets great mileage, but if that was the only reason people bought cars was for high mileage numbers then everybody would either have a Geo Metro or Civic VX in their driveway. Do a search on the site. There are many others that claim to have positive results with WAI. For some reason Saturns do extremely well with WAI/HAI.

I'm just saying I wouldn't dismiss it so quickly.
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Old 03-24-2009, 06:26 AM   #95
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I can't disagree that a really well controlled series of tests would be great. That said, however, we can say something in the absence of them. Copied from the HAI experiment thread:

When there's uncertainty, I just use the following:

(chance of success)*(estimate of benefit) + (fun of trying)
vs
(cost & effort to try) + (chance of damage)*(estimated cost of damage)

In this case everything on the right hand side is very low. Since the chance of success is mixed, and some people are claiming a good sized benefit I think it's worth giving a shot. You may assign different values to these parameters than I do, and rightly so.
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Main Entry: co de pen dence - see codependency
co de pen den cy
Pronunciation: \kō-di-ˈpen-dən(t)-sē\
Function: noun
Date: 1979

: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
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Old 03-24-2009, 07:59 AM   #96
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More good reading:
http://www.nextautos.com/auto-shows/...inject-engine/
Quote:
Mazda has announced its new lineup of direct-injection engines, called the DISI (direct injection spark ignition). The announcement of the performance enhancing, fuel conscious engines comes only weeks after Ford?s EcoBoost announcement.

The I-4 DISI engine seeks to achieve a 15-20 percent improvement in performance and a 20 percent increase in fuel economy over Mazda?s 2.0L engines.

According to the press release, the DISI engine will reduce energy loss and improve thermal efficiency with a variety of technological engineering. This includes cooling the air intake temperature and reshaping the combustion chamber.

Mazda also noted that they are looking to produce direct-injection diesel turbo engine technology that can improve the fuel economy and emissions by 10 percent as well.
http://www.passagemaker-digital.com/.../200903/?pg=81
Quote:
Related to air filter performance is the temparature of the air being consumed by the engine. Warm air is thinner or less dense than cool air, and thinner air burns less efficiently. Therefore, it is desirable to keep the air inlet temperature to a minimum.
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Old 03-24-2009, 10:04 AM   #97
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A SCIENTIFIC test needs to be done. Strick a car on a dyno, stabalize the coolant and oil temps, set a steady speed and maintain the same external air temps and use a scan guage to measure instand MPG and then switch from a external air inlet to an engine compartemt inlet and measure the difference.
An A-B-A-B test would be sufficiently demonstrative - under condition "A" (i.e. cold air) you get a certain result, then you modify it to condition "B" (warm air) and you get a different result, then return the car to its unmodified condition "A" and ensure that the result returns to its previous value.

-BC
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Old 03-24-2009, 10:11 AM   #98
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An A-B-A-B test would be sufficiently demonstrative - under condition "A" (i.e. cold air) you get a certain result, then you modify it to condition "B" (warm air) and you get a different result, then return the car to its unmodified condition "A" and ensure that the result returns to its previous value.

-BC
I 100% agree.

And I love the thread you have in you signature about doing a SCIENTIFIC experiment: http://www.gassavers.org/showthread.php?t=2
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Old 03-24-2009, 11:13 AM   #99
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Warm air allows larger throttle openings and higher effective compression.

Warm air also allows less fuel to be injected for the same mass of air consumed.

Fuel delivery systems add fuel based on temperature as well as mass.

The power delivered by any engine is a direct function of the EFFECTIVE compression. Put a vacuum guage on your engine, keep the revs low, in the 1500 to 2500 range in the highest gear the vehicle can handle. Accelerate with the highest load, lowest revs, and lowest vacuum, without applying enough throttle to get into full load enrichment.

Voila, the secret to the pulse portion of hypermiling.

The concept that making a vehicle more powerful is basically flawed, when you are talking about an economy strategy. This is clearly demonstrated by the difference in mileage between a Civic SI and a Civic VX.

Understand "effective compression". All engines create power utilizing the difference between compression pressure and combustion pressure. The highest effective compression (lowest vacuum reading) is the highest effective combustion pressure for any given mass of fuel delivered.

Take a 2.5 liter 4 cylinder engine on a dyno. Put a 20 HP load of the engine. Measure the fuel consumption at 1700 RPM. Then place a 50 HP load at the same speed and you get 30 more hp, for half the fuel it takes to get the first 20 HP. That is due to effective compression being maximized.

If you have any manifold vacuum you are proportionately reducing the effective compression, as well as efficiency.

Diesels solve the problem by elimination of the throttle butterfly.


regards
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Old 03-24-2009, 11:40 AM   #100
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There's more than throttling losses at partial load. Frictional losses don' t decline quickly with load, so they become a greater proportion as it decreases. This diminishes economy. Diesels suffer from this too. Variable compression can help get around this, but is a much more complicated mechanism.
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Function: noun
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: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
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