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Old 01-25-2009, 04:00 PM   #21 (permalink)
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0.3367 to 0.4428 HP? Seriously? Thats one heck of a dyno setup that can measure stable to this level. I work in a dyno lab, and no matter how stable your engine appears to be running you will get fluctuations in power output. Surely the standard deviation of engine output over the measuring period greatly exceeds the difference in power recorded with and without this device.

If this number is brake output as measured on the dyno, then engine power is NOT increased by 20%. The frictional losses of the engine surely amount to at least 10 HP on an engine like the 300D has.

I think about the only conclusion you could draw from this is that the engine power increased by 0.1 HP, not 20%. How much electrical energy does it take to power this thing anyway?

What a joke. On a side note I had to laugh loudly at the 110 mpg(e) Ford Mustang at the naias yesterday.

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Old 01-25-2009, 04:08 PM   #22 (permalink)
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Was naias good this year? I haven't gone for several years now.
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Old 01-25-2009, 05:55 PM   #23 (permalink)
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Frank, actually I was really pleased with the naias this year. Especially after last year, when even as all the signs of an impending crisis mounted, the big three had nothing but guzzlers. Huge turnaround for this year.

Listening to the spokespeople give demonstrations and hype the efficiency of new concepts was really nice. I work in the auto industry so I found it very reassuring as to the future of the big three. (Except for Chrysler!)

Also awesome was that I saw a lot less people stop to listen about any of the SUVs or trucks on display. (though folks did gush over the shelby mustang)
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Old 01-25-2009, 09:46 PM   #24 (permalink)
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The funny thing is that Chrysler introduced EV's in the 80's... and for some reason, they're not willing to up the ante... or they can't.
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Old 01-25-2009, 10:58 PM   #25 (permalink)
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What I'm enjoying is the apparent effect last summer's price spike had. Even though fuel prices have since dropped off a cliff, people are still seriously looking at smaller, more efficient vehicles, and they are especially looking at the newer technologies.

Interesting times, these. After the last "gas crisis" there was a terrible period during which cars got less powerful, more expensive, uglier, slower, and generally less fun. This time around promises to be much different.
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Old 01-27-2009, 12:03 AM   #26 (permalink)
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That device in the research paper cites the reduction in viscosity for the increase in efficiency.

A much easier way to decrease viscosity of the fuel is to heat it up. The research sounds fake.
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Old 01-27-2009, 12:06 AM   #27 (permalink)
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Quote:
Originally Posted by amcpacer View Post
That device in the research paper cites the reduction in viscosity for the increase in efficiency.

A much easier way to decrease viscosity of the fuel is to heat it up. The research sounds fake.
Bone: Heating fuel also reduces it's density, thus requiring more volume to obtain the same BTU output. This does greatly affect the scenario.

Ideally, you would change the viscosity of the fluid without changing it's density. (Adding water doesn't work for this reason, among others.)
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Old 01-27-2009, 12:53 AM   #28 (permalink)
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Quote:
Originally Posted by Christ View Post
Bone: Heating fuel also reduces it's density, thus requiring more volume to obtain the same BTU output. This does greatly affect the scenario.

Ideally, you would change the viscosity of the fluid without changing it's density. (Adding water doesn't work for this reason, among others.)
Its easy to compensate for a change in fuel density. Just add more fuel. Diesels do this when they switch from summer diesel to winter diesel since winter diesel has a lower btu content per volume.

Actually in a diesel engine changing the fuel temperature causes a big change in the compressibility of the fuel. This affects timing which has a bigger effect than volume of fuel.

A good reference on this type of experiment can be found in NACA-TN-565 on NASA's NTRS server.

They did find an improvement in efficiency but it wasn't 20%. The biggest change was when the temperature exceeded the boiling point of the fuel at TDC. Thus the fuel instantly vaporized upon entering the cylinder.
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Old 01-27-2009, 01:12 AM   #29 (permalink)
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I actually said that you could compensate for the density by adding fuel... this doesn't work on fuel injection systems though (including diesels, without human intervention)... they don't take fuel density into account. Most injection systems are designed to "assume" a specific density, and inject a pre-set amount of fuel based on "duration" and "pressure".

So - this is a case where you'd have to alter more than just one single parameter of your vehicle to keep things in sync. You can't just heat your fuel and expect to change nothing else, which makes it a moot point.
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Old 01-27-2009, 01:35 AM   #30 (permalink)
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Quote:
Originally Posted by Christ View Post
I actually said that you could compensate for the density by adding fuel... this doesn't work on fuel injection systems though (including diesels, without human intervention)... they don't take fuel density into account. Most injection systems are designed to "assume" a specific density, and inject a pre-set amount of fuel based on "duration" and "pressure".

So - this is a case where you'd have to alter more than just one single parameter of your vehicle to keep things in sync. You can't just heat your fuel and expect to change nothing else, which makes it a moot point.
My dumb mechanical injection system has no idea what volume it is injecting. Also my cruise control (if it were working) would just add more fuel until the desired speed was reached. It is sensitive to the timing change due to the change in compressibility though.

A common rail injection system wouldn't suffer from the change in compressibility however and could compensate by just extending the duration of the injection pulse. This is what is done to deal with the change in btu content in winter diesel.

Note: the drop in lubricity of the fuel due to the temp increase and viscosity drop might accelerate wear of your injection system. but this is unrelated to the outcome in regards to fuel efficiency though.

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