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Old 12-22-2016, 01:06 AM   #61 (permalink)
It's all about Diesel
 
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Originally Posted by JohnAh View Post
In the 1940's and 50's there were some bizzarre petrol engine conversions called Hesselman diesels, mainly in trucks and busses. The most common engine was a 6-cyl Volvo engine with low compression (even for a petrol engine, I think it was around 7:1). The engine had powerful spark-plugs for ignition and two slightly special valves per cylinder, giving an extra good swirl. Once started on petrol the Hesselman could switch over and run on the much cheaper oily diesel, -probably with a lot of black smoke and poor efficiency. To keep cylinder temperature up, the idle was kept quite high, and to help it even more, half of the cylinders were completely shut off to make the remaining three work a lot harder. (probably resulting in an extra dense black turd while driving off again...) There were a lot of problems with these engines due to soot and inlet valves that could not rotate the usual way.
Hesselman engines were the earliest application of direct injection in spark-ignited engines, but I never even heard of them being fitted with cylinders shut-off in order to raise the temperatuer while operating on heavy fuels. Surprisingly, at that time the Diesel engines made by Volvo and Scania still featured indirect injection. Anyway, the Hesselman engines were more suitable to use kerosene instead of Diesel fuel.

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Old 12-24-2016, 05:15 PM   #62 (permalink)
NHB
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What makes me quite skeptical is about the life of a rubber belt being soaked on oil.
I haven't heard about any issues with these modern belt bathing in oil. Millions of cars test these belts every day. I think that they are even more reliable than chains.
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Old 12-24-2016, 05:23 PM   #63 (permalink)
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Apart from the cars growing bigger and heavier at each new generation (a weight reduction at this transition is highly uncommon), other issues such as the gear ratio better suited to standard test procedures over real-world efficiency can also be blamed for that.
Cars have been getting leaner for some time already. I would say that here in Europe almost all new models are lighter than their predeseccors. The tide has changed.
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Old 12-24-2016, 05:56 PM   #64 (permalink)
It's all about Diesel
 
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Cars have been getting leaner for some time already. I would say that here in Europe almost all new models are lighter than their predeseccors. The tide has changed.
I'm not in Europe, but anyway, eventually some different alloys used there might provide a higher tensile strenght to weight ratio than what is used in my country, and this would allow some weight reduction. Engine downsizing seems to be taken more seriously there too, while 3-cylinder engines started to become mainstream in my country just about 4 years ago.
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Old 02-27-2017, 02:43 AM   #65 (permalink)
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Ford has introduced 1.5 liter 3-cylinder engine with cylinder deactivation. Interesting to see, how it compares to the competition in 200 hp class. Ford could cover 100-200 hp range with 3-cylinder engines.

Green Car Congress: Next-Gen Ford Fiesta St with new 200 PS 3-cylinder, 1.5L Ecoboost with 3 drive modes; cylinder deactivation
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Old 05-21-2017, 05:05 PM   #66 (permalink)
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Basically just copying motorcycles at this point for a small weight loss, and then knocking down engine displacement since the torque figure needed to propel the car is significantly small under most loads.
Imagine this a Geo metro made 58 lb-ft of torque for a 1690lb car.
A Ford Fiesta makes 148 lb-ft (many contest is under-rated) and weighs 2750.

The above values.
Wt. per lb-ft - 1680/58 = 28.96 pounds per ft-lb of motor torque.
Wt. per lb-ft - 2750/148 = 18.58 pounds per ft-lb of motor torque. 56% better value.

Then Total gearing values for each on the first three gears the Fiesta has about 7.5% more gear, but top gear is much lower on the rpms for the fiesta.
So I say it will drive just fine. It is heavier though so it wont get close to geo metro mpgs, but it will do well for the power and comfort the car has, and well not worrying as much about dying if you rear end someone.
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Old 05-22-2017, 03:00 AM   #67 (permalink)
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2750lbs? What a porker for such a little car!

You may resume what you guys were talking about now...

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