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Gas mileage...good-bad (The Mother thread)

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Old 06-21-02, 05:51 AM   #31
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on my 95 LS400 i get an average of 400 miles per tank. most of my driving is on the highway to and from work but i do drive like a bat out of hell most of the time. usually i cruise at about 80 for the 40 mile hike with short bursts of speed of up to 100 or 110 for passing (i get frustrated really easy on the highway with drivers in the left lane). just recently, i drove 120 miles city using a/c and still got just shy of 400 miles for the whole tank.

this last fill up i used sunoco ultra 94 and my yokohama tires have the 29 psi pressure recommended by the dealer. i'm sure that if i had not used the a/c and drove 65ish-70ish i'd have racked up 500 miles on this tank. i had the 60000 mile serve done at 73000 miles when i acquired the car. now i just passed 94000. i actually get better mileage than my friend who has one of those 4cyl neons. but that's not sayin much. lol.
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Old 06-21-02, 11:08 PM   #32
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Wait, doesn't the alternator run just as fast as the RPMs the engine is running at? It doesn't run faster when you turn on the big amps does it? If that's true then the radio, amplifiers etc won't have any affect on the mileage.
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Old 06-22-02, 05:29 AM   #33
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Actually,

Due to the physics of magnetic induction (Those principles are used to create a flow of current or "electrons" through a conductor that is passing through a magnetic field) an increase of current TO the load FROM such a device as an alternator will increase the amount of energy required to turn it's armature. The simple physics is that the magnetic fields inside of an alternator are always trying to "Line Up" if you will to the North and South poles of the enclosed magnetic field.

The more current flow through the device the stronger the magnetic fields created and hence the harder it is to separate the natural tendancy of fields to align with pole to pole orientation.

Take two pair of horse shoe magnets for example. One pair is very strong in magnetic flux and the other is weak. Allow the ends of the magnets N & S poles to "Attach" for both magnets, the strong pair together and the weak pair together, then try to pull them apart. The magnets with the stronger flux fields will definately be harder to separate than the weaker magnets.

Consider the magnets with the stronger flux fields comparable to the magnetic fields in your alternator under a heavy load, like turning your bright beam headlights on. The heavier the load, the more current required and the more current required the stronger the magnetic fields will be inside the alternator. It will require more torque from the engine to turn the armature inside of the alternator with the headlights on then it will with just the load of a normal running engine.

Anyway, thats the theory. Turning the alternator armature through the magnetic fields at a higher rate of speed increases the frequency and amount of the total output available to the load. It's the RMS (Root Means Square) output value. So two basic things are at play here, the strength of the magnetic field and frequency with which the conductor passes through that magnetic field.

Now, in a circuit such as a car, when the load requirement exceeds the maxium output of the alternator based on it's rated capacity at a specific frequency, part of the load will be supplied by the battery. Typically an alternator needs about 2,500 RPM to achieve it's rated output. So, when you place a heavy load on the alternator and your car is idling, some of that load may be supplied by the battery until the alternator can handle the entire load.

If your load requirement consistantly exceedes the rated output of the alternator it will slowly and methodically discharge your car battery.

So, if you put a big 'ole honking sound system in your car that's a real juice hog and you don't have an alternator that can handle it your going to have troubles.

Now, why do we use alternators instead of generators?? Another story....some other day.
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Old 07-05-02, 07:57 PM   #34
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Guys,

Another update. i have used the engine restore stuff (engine does seem to run quieter and smoother now, even though it was good before), B-12 chemtool fuel injector cleaner (mechanic's recommendation), tires at 40 psi. Road trip from Alpharetta, GA to Folly Beach, SC for the 4th - average mpg has climbed from 17.5 before to 22.5 now (about 80 % freeway at 75-85, rest a mix of city and construction zone stuff). I will check it on the way back home too to verify, but I am very happy with the change. I may still try the Tornado, just for the heck of it.

Thanks for the advice,

rhlight
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Old 07-07-02, 01:29 AM   #35
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I heard that the Tornado doesn't do anything, but I installed it in my other car, and I'm not sure if it was just my imagination, but I felt more power (only around redline though). I also installed a K&N air filter at the same time, but that is only supposed to increase 2-3 horsepower. As far as it saving gas, I did not notice a change, but that's not why I bought it in the first place. After I saw the infomercial in which a car had an increase of 20 horsepower, I bought it. Maybe someone here with access to a dyno could test the HP before and after putting it in the car? Might be worthless, but I am not going to take it out of my car.
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Old 07-07-02, 01:37 AM   #36
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Quote:
Originally posted by rsg
I heard that the Tornado doesn't do anything, but I installed it in my other car, and I'm not sure if it was just my imagination, but I felt more power (only around redline though). I also installed a K&N air filter at the same time, but that is only supposed to increase 2-3 horsepower. As far as it saving gas, I did not notice a change, but that's not why I bought it in the first place. After I saw the infomercial in which a car had an increase of 20 horsepower, I bought it. Maybe someone here with access to a dyno could test the HP before and after putting it in the car? Might be worthless, but I am not going to take it out of my car.
Its not worth the time to dyno that thing.If it really did give a car 20hp everyone would have one in their car and I dont think it gives you better gas mileage either.

There has been tons of threads about this tornado device and its just basically a scam for $$$$$$
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Old 07-07-02, 01:26 PM   #37
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In the city I average 20.5 MPG just did a highway run and I got 25 MPG no speed over 75 we kept an average of 65 MPH I will not complain this better in the city than my 2000 RX300 the highway is about the same. The LS only gets super 93 octane.
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Old 02-18-03, 05:14 PM   #38
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Default 24 mpg, is that all?

My 1992 LS400 gave me 24 mpg, going consistently at 70 mph. That is poor, I think, considering my 1995 MB S420, which seems twice as big, and three times as heavy, gives me 26 mpg under identical conditions on the same road. Not impressed with LS400. What do you guys get?
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Old 02-18-03, 06:24 PM   #39
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Default Re: 24 mpg, is that all?

Quote:
Originally posted by ychachad
My 1992 LS400 gave me 24 mpg, going consistently at 70 mph. That is poor, I think, considering my 1995 MB S420, which seems twice as big, and three times as heavy, gives me 26 mpg under identical conditions on the same road. Not impressed with LS400. What do you guys get?
24 mpg is considered pretty good for the LS. I have seen LS's range from 18-25mpg depending on driving conditions and condition of the car.

As far as the MB S420 being twice as big and 3 times as heavy. Then your MB S420 must be almost 20ft long and 12,000lbs
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Old 02-18-03, 06:27 PM   #40
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24 MPG going 70 MPH consistent is impressive.

I barely get 20 MPH period.

Might need to re-check your figures.

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Old 02-18-03, 06:55 PM   #41
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Nope, the figures are correct, 70 mph, 24 mpg. Consistent on several occasions. I was joking when I said the MB S420 feels twice as big, and 3 times as heavy, but it certainly is a more massive car, and it consistently gives me better gas mileage than the LS400. The MB is certainly more impressive.
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Old 02-18-03, 07:00 PM   #42
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Quote:
Originally posted by ychachad
Nope, the figures are correct, 70 mph, 24 mpg. Consistent on several occasions. I was joking when I said the MB S420 feels twice as big, and 3 times as heavy, but it certainly is a more massive car, and it consistently gives me better gas mileage than the LS400. The MB is certainly more impressive.
Well, Im only getting about 17-20 mpg with my large rims, so your lucky. Plus with the gas prices shooting up to the roof :eek:
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Old 02-18-03, 07:07 PM   #43
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Wow 24MPG? I've never gotten that even on a 300 mile cruise.

My last tank was about 17MPG.

I've gotten 14 before with the K&N filter (boooo)
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Old 02-18-03, 07:43 PM   #44
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I used to get 260 without exauhst and i think now I get 300 miles per tank if I am lucky.
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Old 02-18-03, 10:06 PM   #45
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my 2.2L 3SGE corolla got 40MPG on my way to NJ from Canada.

24MPG is pretty good for a 4L V8 and a 3500+LB car. maybe it is because the car is a little old and the engine needs some care.
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Old 02-18-03, 10:06 PM
 
 
 
 
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