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matt36415 11-18-2018 05:51 AM

Diesel vs petrol question
I drive a courier van, ford transit, manual 6 speed, diesel, 2.2 litre I think. Over a 480km trip, 90% at 100km/h - 60mph, it regularly gets 6.7-7.0 litres per 100km. My car, 3.5litre V6 Camry, petrol, 6 speed auto gets 7.4 litres per 100km on a good trip for the same road at the same speed... over many trips. Van has a far larger frontal area and is fairly brick shaped, has a bull bar too and Im pretty sure its heavier.

Why can the van do better than my car? I understand auto vs manual but there must be more going on, does diesel have far more energy per litre? I drive the van pretty hard but usually I am in no rush in my car.

Nedlom 11-18-2018 07:33 AM

Yep, diesel has more energy per unit, plus diesel engines have a more efficient combustion process.

slowmover 11-18-2018 09:47 AM

Work vehicles are often (maybe usually) geared for steady state cruise. Can handle being fully loaded in terms of overall powertrain performance. But can slow up to speed.

Passenger vehicles are overpowered. Set up for acceleration.

While not strictly accurate, the above makes sense when one tries to use one vehicle in place of the other.

oil pan 4 11-18-2018 11:27 AM

If the diesel is a turbo diesel then it really isn't fair.
You have 2 engines in the diesel versus one in the gas.
That turbocharger is working to recover waste hest in the exhaust to force more air into the engine.
Diesels get better fuel economy with more air.

airbiteses 11-18-2018 12:10 PM

Yes, they are more economical but they are more harmful to the environment, they are carcinogen when breathing fumes, and they are more expensive to repair but these new cars with this engine.

oil pan 4 11-18-2018 12:51 PM


Originally Posted by airbiteses (Post 584081)
Yes, they are more economical but they are more harmful to the environment, they are carcinogen when breathing fumes, and they are more expensive to repair but these new cars with this engine.

Gasoline fumes are loaded with benzene which is a major cancer causer.
Is burning more fuel not also harmful to the environment?

RedDevil 11-18-2018 02:34 PM

If you live anywhere near Autobahn 40 in Germany you'd better think twice before buying a diesel car...

Here in Holland more and more cities move towards banning diesels of a certain age, or altogether, in order to meet the micro particulate and NOx air pollution standards.
Recent research has shown micro particulates are far more harmful than was previously assumed, so there's no turning back this trend. Diesel is on its way out, especially in densely populated areas.

slowmover 11-18-2018 08:48 PM

Anti-diesel ”reasearch” is pretty well bunk. Politically skewed. Like the faked dangers of second-hand cigarette smoke. False, in that someone’s profit (or power) is what’s really at stake.

The energetic content of diesel makes it indisposable. Non-replaceable. Emissions controls have changed the rest.

The number of vehicles to service urban sprawl is the problem.

Why cities have sprawled is what you aren’t allowed to ask. “Why do we have commuters?” Power and profit are at stake.

Other choices would have precluded what you think of as a dilemma.


RedDevil 11-19-2018 05:01 AM

Oh yeah, it is pretty well bunk.

Health concerns
General concerns
Emissions from diesel vehicles have been reported to be significantly more harmful than those from petrol vehicles.[38][better source needed] Diesel combustion exhaust is a source of atmospheric soot and fine particles, which is a component of the air pollution implicated in human cancer,[39][40] heart and lung damage,[41] and mental functioning.[42] Moreover, diesel exhaust contains contaminants listed as carcinogenic for humans by the IARC (part of the World Health Organization of the United Nations), as present in their List of IARC Group 1 carcinogens.[7] Diesel exhaust pollution is thought[by whom?] to account for around one quarter of the pollution in the air in previous decades,[when?] and a high share of sickness caused by automotive pollution.[43][better source needed]

Occupational health effects
Two handheld instruments with screens and wires on a white background
Two diesel particulate matter monitors
Exposure to diesel exhaust and diesel particulate matter (DPM) is an occupational hazard to truckers, railroad workers and occupants of residential homes in vicinity of a rail yard, and miners using diesel-powered equipment in underground mines. Adverse health effects have also been observed in the general population at ambient atmospheric particle concentrations well below the concentrations in occupational settings.

In March 2012, U.S. government scientists showed that underground miners exposed to high levels of diesel fumes have a threefold increased risk for contracting lung cancer compared with those exposed to low levels. The $11.5 million Diesel Exhaust in Miners Study (DEMS) followed 12,315 miners, controlling for key carcinogens such as cigarette smoke, radon, and asbestos. This allowed scientists to isolate the effects of diesel fumes.[44][45]

For over 10 years, concerns have been raised in the USA regarding children's exposure to DPM as they ride diesel-powered school buses to and from school.[46] In 2013, the Environmental Protection Agency (EPA) established the Clean School Bus USA initiative in an effort to unite private and public organizations in curbing student exposures.[47]

Concerns regarding particulates

Heavy truck, with visible particulate soot
Diesel particulate matter (DPM), sometimes also called diesel exhaust particles (DEP), is the particulate component of diesel exhaust, which includes diesel soot and aerosols such as ash particulates, metallic abrasion particles, sulfates, and silicates. When released into the atmosphere, DPM can take the form of individual particles or chain aggregates, with most in the invisible sub-micrometre range of 100 nanometers, also known as ultrafine particles (UFP) or PM0.1.

The main particulate fraction of diesel exhaust consists of fine particles. Because of their small size, inhaled particles may easily penetrate deep into the lungs.[1] The polycyclic aromatic hydrocarbons (PAHs) in the exhaust stimulate nerves in the lungs, causing reflex coughing, wheezing and shortness of breath.[48] The rough surfaces of these particles makes it easy for them to bind with other toxins in the environment, thus increasing the hazards of particle inhalation.[20][verification needed][1]

A study of particulate matter (PM) emissions from transit buses running on ULSD and a mixture of biodiesel and conventional diesel (B20) was reported by Omidvarborna and coworkers, where they conclude PM emissions appeared lower in cases of mixed diesel/biodiesel use, where they were dependent on the engine model, cold and hot idle modes, and fuel type, and that heavy metals in PM emitted during hot idling were greater than those from cold idling; reasons for PM reduction in biodiesel emissions were suggested to result from the oxygenated structure of biodiesel fuel, as well as arising from changes in technology (including the use of a catalytic converter in this test system).[49] Other studies concluded that while in certain specific cases (i.e. low loads, more saturated feedstocks, ...), NOx emissions can be lower than with diesel fuel, in most cases NOx emissions are higher, and the NOx emissions even go up as more biofuel is mixed in. Pure biodiesel (B100) even ends up having 10-30% more NOx emissions compared to regular diesel fuel.[50]

Specific effects
Exposures have been linked with acute short-term symptoms such as headache, dizziness, light-headedness, nausea, coughing, difficult or labored breathing, tightness of chest, and irritation of the eyes and nose and throat.[51] Long-term exposures can lead to chronic, more serious health problems such as cardiovascular disease, cardiopulmonary disease, and lung cancer.[39][40][52] Elemental carbon attributable to traffic was significantly associated with wheezing at age 1 and persistent wheezing at age 3 in the Cincinnati Childhood Allergy and Air Pollution Study birth cohort study.[53]

The NERC-HPA funded Traffic Pollution and Health in London project at King's College London is currently[when?] seeking to refine understanding of the health effects of traffic pollution.[54] Ambient traffic-related air pollution was associated with decreased cognitive function in older men.[42]

Mortality from diesel soot exposure in 2001 was at least 14,400 out of the German population of 82 million, according to the official report 2352 of the Umweltbundesamt Berlin (Federal Environmental Agency of Germany).[citation needed]

The study of nanoparticles and nanotoxicology is in its infancy, and health effects from nanoparticles produced by all types of diesel engines are still being uncovered. It is clear, that diesel health detriments of fine particle emissions are severe and pervasive. Although one study found no significant evidence that short-term exposure to diesel exhaust results in adverse extrapulmonary effects, effects that are correlated with an increase in cardiovascular disease,[55] a 2011 study in The Lancet concluded that traffic exposure is the single most serious preventable trigger of heart attack in the general public, as the cause of 7.4% of all attacks.[41] It is impossible to tell how much of this effect is due to the stress of being in traffic and how much is due to exposure to exhaust.[citation needed]

Since the study of the detrimental health effects of nanoparticles (nanotoxicology) is still in its infancy, and the nature and extent of negative health impacts from diesel exhaust continues to be discovered. There is little controversy, however, that the public health impact of diesels is higher than that of petrol-fuelled vehicles despite the wide uncertainties.[56]
But hey, wikipedia is bunk. Let's roll some more coal.

Lemmy 11-19-2018 11:28 AM


Originally Posted by oil pan 4 (Post 584077)
If the diesel is a turbo diesel then it really isn't fair.
You have 2 engines in the diesel versus one in the gas.
That turbocharger is working to recover waste hest in the exhaust to force more air into the engine.
Diesels get better fuel economy with more air.

But then the petrol engine has ignition advance, which the diseasel lacks.

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