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  #46  
Old 03-02-2009, 09:00 AM
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Quote:
Originally Posted by Mark DiSilvestro View Post
I don't think electrical usage is a major factor in comparing diesel to gasser efficiency, though it might be a factor in comparing reliability!
Fortunately, not even an electric lift-pump in any of my diesels, and my Benz gassers have only ignition and, on my 250s, a couple tiny fuel cut-off solenoids on the carbs - hardly a major electrical drain.

Happy Motoring, Mark
Well....for an alternator to produce 20 amps in a perfect world (with no other losses) equals about .35 horsepower on a constant basis....240 watts. That does add up over time. Gas has less energy in it per gallon than diesel in the first place. So the electrical needs of a gasser only add to the waste. Plus they use a lot more fuel at idle to accomplish the same task....and have a lower thermal efficiency.

A gallon of gasoline has enough energy in it to run a 1500 watt household heater for 24 hours......diesel a few more hours than that.

Scary to think that the average gasser uses 2.5-3+ gallons of gas PER HOUR when cruising the freeways at 70-75mph! With only a 30-35% efficiency...thats a LOT of waste heat. Its mind boggling.
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'17 Metris(VITO!) - 8k - wifes (OC-10k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
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  #47  
Old 03-02-2009, 09:10 AM
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Ive been seeing alot of 450sl s for sale ,a 380sl was real promising .The amg car Im keeping secret until I can sneak it from the owner.A 617 in an sl body ,hmmmm.
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  #48  
Old 03-02-2009, 09:27 AM
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If the 380 has more power/torque than a M103....I'd be game for having one. The only place the 6 lacks is in "initial torque"...which I bet that extra .8 liters and 2 cylinders can account for on the 380....I do notice the M103 has a higher HP rating than the 380 though.....Perhaps a 420 is more like it.

The torque issue isn't that big of a deal since my wife generally drives the 300E and she drives like a granny..... She's all about economy. Fuel is cheap I say!
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 78k - mine - (OC-80,500)
'17 Metris(VITO!) - 8k - wifes (OC-10k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
'01 E320 - 171k - dad's (OC-171,500)
'07 E350 Wagon - 131k - dad's (OC-132,500)
'01 SL500 - 49k - dad's (OC-52,000)
'09 E350 4matic Sedan - 129k - Brothers (OC-128,000)
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  #49  
Old 03-02-2009, 09:42 AM
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Originally Posted by pawoSD View Post
Interesting. The SLR gains 33% more mileage over the veyron, which is interesting in that its engine has a max output of 626hp.....while the veyron is 1001....so its about 30ish % less hp.....thus the 1 extra mpg. Thats weird!
Its not weird at all, as speed increases it takes more and more power to overcome the air friction, not in a linear way either.

The Veyron uses only about 150hp to reach 150mph, and most other modern cars will to with under 250hp. The other 850hp is needed to go the last 100mph.

So to push an SLR from 205 to say 250 would probably require another 300-500 hp.

I think the Veyron has a 26-30 gallon tank, I would imagin at those speeds like most race cars anything around 1mpg would be good. Luckly the owners of such cars don't give a damn about fuel mileage, more so since these are not track cars.

Whats far more impressive than the Veyron is the McLarean which managed to top out in the low 240's 20 years ago. It "only" has about 650hp but it weighs less than half of what these modern cars do.
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  #50  
Old 03-02-2009, 09:58 AM
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The fuel use between the three cars is largely a matter of aerodynamic drag, which is around 98% of total fuel used at those speeds.

It would be amazing if the C111 diesel could get 15mpg at 250mph, in fact quite impossible even if the aerodynamics were better than those of the 30year newer cars.

Anybody know what kind of fuel mileage Audi gets in endurance racing (LeMans, Daytona) with the Tdi?
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  #51  
Old 03-02-2009, 10:12 AM
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Originally Posted by freeride View Post
x2

After having 380SEC, desire for 560 is a natural thing
I suppose so. For a while I always had a 560SEL on my mind...but I got into thinking, I rarely have more then one person in the car anyways so it would be kinda wasteful having to LWB w126. SO naturally the SEC became the perfect candidate, its a better drivers car but you still have the option to carry 4 people. (Unlike say an SL)
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  #52  
Old 03-02-2009, 10:15 AM
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Quote:
Originally Posted by DslBnz View Post
Nobody knows fuel consumption until they take a Mercedes 6.9 to 140 mph and hold it there.
Well I guess I know what fuel consumption IS
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  #53  
Old 03-02-2009, 11:16 AM
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Quote:
Originally Posted by pawoSD View Post
Well....for an alternator to produce 20 amps in a perfect world (with no other losses) equals about .35 horsepower on a constant basis....240 watts. That does add up over time. Gas has less energy in it per gallon than diesel in the first place. So the electrical needs of a gasser only add to the waste. Plus they use a lot more fuel at idle to accomplish the same task....and have a lower thermal efficiency.

A gallon of gasoline has enough energy in it to run a 1500 watt household heater for 24 hours......diesel a few more hours than that.

Scary to think that the average gasser uses 2.5-3+ gallons of gas PER HOUR when cruising the freeways at 70-75mph! With only a 30-35% efficiency...thats a LOT of waste heat. Its mind boggling.
I'm just saying that electrical load is not a MAJOR factor when comparing gassers to diesels.
And don't forget to add in the electrical load required to recharge that big diesel battery, after cycling those glowplugs and cranking that oversize diesel starter.
I'd also be willing to bet that modern diesels, with their computetrised injection are now carrying an elecrical load similar to their gas counterparts.
And the .35 horsepower consumed by modern electronic engine systems, is certainly compensated for by the big imrovement in the efficiency of those same engines.
On the other hand, I might not enjoy, or even be able to keep any of these modern high-tech marvels going when they're 30 or 40 years old.

Anyway, If I was that concerned about wasting .35 horsepower, I could save a whole lot more by never using the AC in ANY of my cars. But THAT isn't going to happen!

Happy Motoring, Mark
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Last edited by Mark DiSilvestro; 03-02-2009 at 11:31 AM.
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  #54  
Old 03-02-2009, 11:22 AM
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True..... A/C is a real power hog.....I've tested it on our M103 a couple times and its like dragging an anchor (especially with the 2nd gear start).....I fear what the mpg's are with that turned on during a regular basis.... Once the engine is over 2000rpm you can't tell that its on though.

Our Rav4 is massively slowed down by the A/C....its 240d style with it on.
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 78k - mine - (OC-80,500)
'17 Metris(VITO!) - 8k - wifes (OC-10k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
'01 E320 - 171k - dad's (OC-171,500)
'07 E350 Wagon - 131k - dad's (OC-132,500)
'01 SL500 - 49k - dad's (OC-52,000)
'09 E350 4matic Sedan - 129k - Brothers (OC-128,000)
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  #55  
Old 03-02-2009, 11:34 AM
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During the warm summers I had to shut off the 240D's A/C when going up mild hills and or even starting off the line. It provided too much drag. Sometimes when coasting down a long hill I would turn on the A/C to slow the car.....a bit dramatic but it was noticable
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  #56  
Old 03-02-2009, 11:41 AM
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I imagine its quite a shock going between a 6.9 and a 240D....
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 78k - mine - (OC-80,500)
'17 Metris(VITO!) - 8k - wifes (OC-10k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
'01 E320 - 171k - dad's (OC-171,500)
'07 E350 Wagon - 131k - dad's (OC-132,500)
'01 SL500 - 49k - dad's (OC-52,000)
'09 E350 4matic Sedan - 129k - Brothers (OC-128,000)
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  #57  
Old 03-02-2009, 12:21 PM
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Quote:
Originally Posted by diametricalbenz View Post
During the warm summers I had to shut off the 240D's A/C when going up mild hills and or even starting off the line. It provided too much drag. Sometimes when coasting down a long hill I would turn on the A/C to slow the car.....a bit dramatic but it was noticable
It appears from your signature, that your 240D has since been souped-up a bit.
On the other hand, I have a tired '82 240D/automatic. Last summer I got the AC going, with a conversion to R134a, for even more AC drag! It's like turbo-charging when I switch off the AC in that car!

Somewhere, I have a '70s-vintage 'Power-Saver' device, still in the box. It's a vacuum actuated switch, designed to be connected to an intake manifold vacuum source, and automatically shut off a car's AC compressor during hard acceleration. Somethng like these Power-Savers were often needed on the typical underpowered emission-strangled small cars back then.
Of course it wouldn't work on a diesel, but I'm sure a switch could be fitted someplace on the throttle-linkage of my 240D.

Happy Motoring, Mark
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Last edited by Mark DiSilvestro; 03-02-2009 at 12:27 PM.
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  #58  
Old 03-02-2009, 12:55 PM
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Originally Posted by pawoSD View Post
I imagine its quite a shock going between a 6.9 and a 240D....
It really is. Our household has a large spread of engine displacements.

1.7L Honda Gas to 6.9L Gas
2.4L Diesel(well 3.0 now) to 5.9L Diesel
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  #59  
Old 03-02-2009, 01:02 PM
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Quote:
Originally Posted by Mark DiSilvestro View Post
It appears from your signature, that your 240D has since been souped-up a bit.
On the other hand, I have a tired '82 240D/automatic. Last summer I got the AC going, with a conversion to R134a, for even more AC drag! It's like turbo-charging when I switch off the AC in that car!

Somewhere, I have a '70s-vintage 'Power-Saver' device, still in the box. It's a vacuum actuated switch, designed to be connected to an intake manifold vacuum source, and automatically shut off a car's AC compressor during hard acceleration. Somethng like these Power-Savers were often needed on the typical underpowered emission-strangled small cars back then.
Of course it wouldn't work on a diesel, but I'm sure a switch could be fitted someplace on the throttle-linkage of my 240D.

Happy Motoring, Mark
The car is not done yet unfortunately. The engine is worn out so I opted to have the motor swapped out.

A vaccum device would work but if it has turbocharging that wouldn't work, you'd need some sort of throttle position device with perhaps a 20 second delay timer to solve the partial throttle liftoff issue if you were on a long uphill climb for example.
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1996 Dodge Ram 5.9L Cummins 12V 4(A) 4.10 - 163K - For Sale
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  #60  
Old 03-02-2009, 01:10 PM
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Could always just use an electrical switch mounted to the throttle linkage somewhere that cuts the A/C out when you're applying more than 70-80% of the throttle or something...that'd be easy.
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 78k - mine - (OC-80,500)
'17 Metris(VITO!) - 8k - wifes (OC-10k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
'01 E320 - 171k - dad's (OC-171,500)
'07 E350 Wagon - 131k - dad's (OC-132,500)
'01 SL500 - 49k - dad's (OC-52,000)
'09 E350 4matic Sedan - 129k - Brothers (OC-128,000)
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