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They do not rev above 4000 rpm so they last longer. Simple. Regards Peter
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I know they're not diesel, but does that almost guarantee no-one's likely to get 200k miles out of a Honda V-TEC?
Any high-mile S2000s out there..?
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Don't believe it, my experience with Ford Mondeo diesel engines in my company fleet is that they bite the dust after 150K the petrol engines are good for 200k, its just a myth look at land rover diesels lots of work required, new injectors etc at 40k, they are generally serviced more often.
Enjoy life buy a petrol, no mess at the filling staion, no stinky slipperry shoes, nice smooth acceleration, no flat spots, no black fumes to give other drivers cancer, and listen, i can't here the engine ticking over, the diesel driver is being shaken to bits, ooops he's a hundred yards behind. he he he!
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Indeed Flatfour - but 30 mpg? No thanks.
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I think Newton might be right. (equal and opposite reactions).
For every horsepower (?) produced at the flywheel another horsepower has to be dissipated within the engine. Big heavy engines can cope. Small engines can't
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The petrol engine just gets loaded more often than the diesel. Take the example of the motorway - cruise at 70-75mph and you need to overtake. The diesel (with turbo) accelerates gently with plenty of power and you can safely merge into faster lanes with plenty to spare. Equivalent petrol engines are capable of the same but, unless you can plan ahead and start accelerating before you pull out, you have to thrash them a lot harder to achieve it. And petrol is about a squillion times more poisonous than diesel.
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It doesn't have to be knackered after 150,000 to 200,000 miles.
One Million Miles On Mobil 1
As one example of the level of testing undertaken, a 1990 model year import car was tested for 1,000,000 miles with Advanced Formula Mobil 1 and showed extremely low wear. Oil drain intervals were 7,500 miles, as specified by the manufacturer, and Mobil 1 was used from the very first day of testing.
After the end of the test, with 1,001,120 miles on the vehicle, the engine was removed and internal components were inspected and measured. Overall engine wear was extremely light. In fact, with the exception of light to moderate wear on the camshaft and followers, no other significant engine wear was noted. Oil consumption over the entire test was just 0.040 quarts/1,000 miles ? the equivalent of just one quart every 25,000 miles
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I'm not convinced that diesels do last longer. You have to compare like for like in each situation.
Bigger petrol-engined cars can do phenomenal mileages - look at 2million mile Voilvo man. Do diesels last so long?
Virtually all lorries are diesels, so of course they appear to last a long time. But petrol lorries used to be commonplace (taxed off the roads). Army lorries were all petrol, and those big Bedford RLs look as if they would go on for ever.
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Cliff,
"Army lorries were all petrol,"
But not for many years now - just about everything is diesel.
To be fair the logistics of storing & transporting fuel - particularly on operations - is an important factor in the choice of a common fuel for the 'Green Fleet' and generators etc.
C
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Cliff, "Army lorries were all petrol," But not for many years now - just about everything is diesel.
I know, I meant back in WW2 days, and for a long time after.
In the late 60s I remember the standard army lorries were petrol. I have memories of riding with a corporal who thrashed one across army roads on Dartmoor, sliding it round corners like a sports car.
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If you look back at The Times newspaper from the 1930s you'll find lots of articles about this newfangled thing called the diesel engine and lots of discussion about whether they were be as reliable and economical to run in a truck as petrol. Ha! I reckon we're in a similar situation (in this country) with cars, with loads of people scared of this thing they don't understand but have heard lots of rumours about. How big would a petrol engine have to be and how many cylinders would it need to have to pull 40 tonnes at 70mph? Most trucks these days are more than capable of that.
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"How big would a petrol engine have to be and how many cylinders would it need to have to pull 40 tonnes at 70mph?"
The short answer is not as big as the diesel! Petrol engines were used extensively for trucks and buses in the US until it became expensive ($1/gallon, hah!). Not too many diesel aeroplanes yet, I'm glad to say...
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"Not too many diesel aeroplanes yet, I'm glad to say... "
And how many petrol engined ones? Well at least those comparable with 40 tonne trucks rather than those comparable with cars that carry 4 passengers not a couple of hundred?
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"Not too many diesel aeroplanes yet, I'm glad to say... "
Well, the chances of one runnig at say 5000 ft with sub zero temperatures - not high I'm sure!
My sister and BiL had a Discovery in Khasakstan. Only they had to go for the V8 Petrol. I say "Had to", they didn't want the diesel to freeze!
Hugo
"Forever indebted to experience of others"
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Depends when you're talking about. Pre-jet area, practically all of them of course, but there still a few transport planes, mostly radial-engined. There were some magnificent engines, too, such as the 27-litre V12 Merlin and the Pratt & Whitney 18-cylinder Twin Wasp radial, both of which powered both fighters and bombers (sports cars and trucks, by analogy).
I was just trying to correct an apparent impression that only diesels were capable of serious amounts of grunt. A ride behind any big petrol V8 should help correct that, however (preferably a 427 Cobra)... :-)
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Ooh, and I should have mentioned the Napier Sabre H-24 (effectively two flat-12's on top of each other) which produced almost 4000hp from a mere 36 litres over 50 years ago. Mind you, that did have some methanol to help it along.
BTW, that would a wonderful fuel to use now (easily obtained from renewable resources) but of course politics prevents it.
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JBJ; more than you yhink, but not v. friendly. WW2 Junkers 2-stroke diesels aircraft engines were quite numerous. Some work now going on for less belligerent, smaller scale applications. Not by Junkers though.
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Thanks, Nortones. I did know that there were some new small ones appearing, although I still think that for an application where smoothness and lightness are paramount, they are less than ideal. I worked next to a small factory that was prototyping one a few years ago, and it shook the place apart whenever they ran it (as well as making the most appalling racket!)
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Hi JBJ
Have you any idea what the fuel consumption was like for the same power? Pretty bad I suspect to trigger such a radical shift. It strikes me that in general petrol engines that produce a lot of power (such as in F1 cars) tend to have a lot of small cylinders (around 300 to 500cc per cylinder seems to be optimal) whereas diesel engines that produce a lot of power (power stations, ships) have a few huge cylinders. So I guess the current Ferrari V10 is powerful enough to pull a 40 tonne truck at 70mph, but 17,000 rpm is hardly fuel efficient or convenient.
Chris
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One advantage diesel engines have is their scalability to cope with different applications. This is well illustrated by the huge two-stroke, direct-drive diesel engines used in large merchant ships.
To give you some idea of the statistics:
MAN B&W 14K98MC 2-stroke marine diesel engine
Bore: 980mm
Stroke: 2660mm
No. of cylinders: 14
If you work out the cubic capacity of this engine it comes to..... over 28,000 litres!!
And the power output? Wait for it..... 108,920 bhp!!!! And all at 94rpm!
OK, getting away from the topic of the original post somewhat, but it illustrates the versatility of the diesel engine.
Rgds,
Jon
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Jon - While I was composing mine... Makes the Sulzer look quite speedy! :-)
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"108,920 bhp!"
Of course, that's only 4hp/litre... (but they are nearly 50% efficient, which is why they are used)
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Well, specific fuel consumption will always be worse for a petrol engine, as even I have to admit that they are less efficient. The point I was trying to make was that petrol engines can do the same job - it's just that the ones we usually see are smaller and designed for power at high revs rather than torque at lower speeds. With diesels, there's less choice, as they can't rev all that high (because of the way the fuel burns), and although they have a flat torque band, it's not very wide, which is why diesel lorries have to have lots of gears.
The bigger the individual cylinders (and the longer the stroke), the faster the piston has to go to complete a revolution, so small multi-cylinder engines can spin faster without tearing themselves apart, but if you just want lots of grunt (torque), a fewer big cylinders will suffice (and will be cheaper to build and maintain). An extreme example is the Sulzer 2-stroke diesel designed for ships, which has a 3-foot bore (you climb inside to de-coke it), an 8-foot stroke and produces maximum power at 100 rpm...
WRT the Ferrari F1 engine in a lorry, it would need a lot of gearing and a big clutch to get moving, I think!
To return to the original topic, the thing that affects engine wear the most is duty cycle. A small car driven on frequent short journeys is bound to wear out sooner than a long-haul truck. The same would still apply if the car was a diesel and the truck had a petrol engine.
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"So I guess the current Ferrari V10 is powerful enough to pull a 40 tonne truck at 70mph, but 17,000 rpm is hardly fuel efficient or convenient."
ONly if it was doing 70 mph at the time you hitched the truck up. A 900bhp 17k revs ferrari f1 would not be able to pull away if attached to a 40 ton truck
(anyway the rear wing would pull off where you attached the rope)
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"And petrol is about a squillion times more poisonous than diesel."
Not so, jeds. Petrol is a product of a higher distillation process than diesel. You could even drink (a small quantity of) petrol and not harm yourself. Diesel? Don't think so...
Vagelis.
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I'd advise strongly against drinking petrol in any quantity! Petrol is classified as 'Harmful by ingestion': because of the aspiration hazard i.e. the risk of chemical pneumonitis, and not because of its acute toxicity i.e. poisoning, properties, which is a case by case variable depending on additives, sulphur and lead content remnants. The presence of up to 5% benzene also means that petrol is classified as Carcinogenic. Not to mention flammable poo, when the residues leave their temporary home. Usual disclaimers as I am not currently au fait with COSHH etc.
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Nortones, with your permission allow me to clarify "chemical pneumonitis" in laymans terms as this happened to an uncle of mine after digesting petrol during a syphoning exercise. In short he died. Months later. Suffocated. Lungs like lace curtains according to the pathology report.
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I know a farmer (well, I say farmer - more of a farmer one-cow really. But a great character) who has been taking the odd sip of diesel, when syphoning from one clapped out old machine to another, for about 40 years. He reckons it keeps his sinuses clear. Not that I am recommending it but, as mentioned above, you would not last long if you tried the same thing with petrol.
In any case, I was really referring to emissions - don't get me wrong, they're both pretty toxic but petrol emissions are microscopic and are much more easily absorbed into the blood stream. Ironically, people think diesel is more harmful because of the visible 'choking black smoke'. In fact the smoke is visible because the particles are massively bigger and, although it doesn't look pretty, this makes diesel emissions less easy to absorb.
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Diesel engines may last longer, but their owners don't. Anyone remember the recent research showing how how taxi drivers are at increased cancer risk from inhaling diesel fumes all day?
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Not necessarily diesel fumes. Most traffic in town is petrol engined, and the atmosphere in a taxi drivers cab, historically, has been full of nasties from smoking. Ordrs of magnitude more important, I'd guess. Defra summary:
"By contrast, a study of lung cancer in professional drivers in Sweden showed an increased risk among those working in the city of Stockholm (Jakobsseen et al., 1997), especially in short-distance lorry drivers; these findings allowed for the effects of smoking and the authors suggested that exposure to traffic fumes might have been responsible, although no data were available on atmospheric concentrations of PAHs within the cabs. A study in Denmark, which focused upon employed men who were diagnosed with lung cancer between 1970 and 1989, also revealed a 31 to 64% excess risk of lung cancer in bus, lorry and taxi drivers (Hansen et al., 1998). The smoking habits of Danish drivers and those in other types of employment were found to be similar. However, in the absence of exposure measurements, the contribution of PAH exposure to this result is unclear.
Summary
28. There is clear evidence that PAH mixtures are carcinogenic in humans and several individual PAHs are carcinogenic in experimental animals. Cancers result from exposure to PAHs over several decades. Increased risks of lung cancer, in particular, have been associated with increased concentrations of PAHs in the workplace. There is epidemiological evidence of an association between urban air pollution and excess risk of lung cancer in those most highly exposed, but risks cannot be estimated confidently from these data because of possible confounding by smoking and lack of information on historical exposure levels."
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Thats fine RF, but an unfortunate end for your Uncle.
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