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I had a good blast down the M3 last night in the Berlingo, took the long way home and kept my foot to the floor to give it a good Italian tune up after lots of town work.
As fifth is an overdrive the revs never go over about 4000, as long as the oil/coolant is topped up and timing belt is good is there anyway this is bad for the engine?
The temperature gauge didn't move and it felt much peppier afterwards.
I know diesels like to be worked, but I want to know where work becomes abuse!
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Abuse I would say is very rapid and sudden increases or decreases in revs, especially when the engine is cold.
Many years ago I rented a non-turbo diesel Fiat Doblo which was very sluggish. After two weeks of wringing its neck up mountains and along motorways, the economy improved and the perfomance was much sharper.
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is there anyway this is bad for the engine?
Isn't yours the 1.9 xud 71hp engine? if so, I think you should be fine, the specific output is quite low.
The coolant temperature is not a good indicator of stress. It is particular components that overheat (exhaust valves, piston crowns valve bridge etc etc.) rather than the radiator being unable to disipate heat.
For a good turbo diesel, an output of about 50hp/litre is the most you can really expect under continuous conditions without overheating starting to become a problem.
So all these 180+hp 2.0 diesels rely on the fact that their drivers can't use the maximum output for more than a few seconds at a time in the real world!
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I think as long as you've waited till it's warmed up and the oils changed regularly it shouldn't be a problem.
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Isn't yours the 1.9 xud 71hp engine? if so, I think you should be fine, the specific output is quite low.
The coolant temperature is not a good indicator of stress. It is particular components that overheat (exhaust valves, piston crowns valve bridge etc etc.) rather than the radiator being unable to disipate heat.
For a good turbo diesel, an output of about 50hp/litre is the most you can really expect under continuous conditions without overheating starting to become a problem.
So all these 180+hp 2.0 diesels rely on the fact that their drivers can't use the maximum output for more than a few seconds at a time in the real world!
I knew you'd come through with an answer and a half! Thanks.
Yes mine is the DW8, basically an updated XUD as far as I know.
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I suppose it's rare to use maximum output in most passenger cars for more than a few seconds at a time, although a friend used to try his hardest in an old Fiat 126 ... foot nailed to the floor EVERYWHERE, in all gears ...
But it's an interesting point. Surely a volume production engine would be tested by the manufacturer (either on the bench or on a test track) to withstand maximum output continuously for minutes, even hours at a time?
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Yes, I'm sure they do test them like that. But do they test them for day after day in heavy traffic, where a completely different type of wear and tear results.
I'm sure Mss's Italian tune-up was exactly the right thing to do. It's very difficult to over-rev a diesel anyway.
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When GM torture tested the Northstar 4.6 V8, (which has a low specific output by today's standards), they had to run it at an AFR of 10 to stop the pistons and exhaust valves from overheating. That is more fuel enrichment than even a heavily boosted turbo engine would be allowed to run.
When VW put their 1.9 TDI engine in cars they permit power levels of 150hp+. When they put it in vans, the maximum they allowd was about 110. In continuous duty industrial applications, the maximum permitted was under 100hp.
Engine speed makes little difference. The most powerful truck engine commercially available is the Scania 16 litre V8. It runs at about 730hp-only about 45hp/litre. The 14 litre Cummins ISX run about 600hp-43hp /litre. These engines only spin about 1800 RPM. That's about all you can manage under sustained conditions. And those engines are built much tougher than car engines...
80+hp/litre cannot be sustained for long without overheating. They rely on heat soak to keep component temperatures down.
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80+hp/litre cannot be sustained for long without overheating. They rely on heat soak to keep component temperatures down.
Interesting about the Northstar and about specific outputs. Still sounds like inadequate design / provision for cooling to me.
I'm aware it's not comparing apples with apples, but yer average motorcycle engine design has been producing well in excess of 100bhp/litre for decades, relying on techniques like oil jets to cool the underside of pistons, oil coolers, and high-volume cooling systems to keep the temps down.
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" techniques like oil jets to cool the underside of pistons, oil coolers, and high-volume cooling systems to keep the temps down. "
Modern diesels rely on oil cooling of pistons as well....
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Perhaps bike engines fare better because they have smaller cylinders giving a larger heat seak area per bhp, or is that nonsense?
They also tend to use more fuel for the same power, therefore presumeably emlpoy some fuel "cooling"..... certainly true of the two strokes.
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Perhaps bike engines fare better because they have smaller cylinders giving a larger heat seak area per bhp, or is that nonsense? They also tend to use more fuel for the same power, therefore presumeably emlpoy some fuel "cooling"..... certainly true of the two strokes.
Speaking as an owner of a Suzuki 2-stroke triple, I can vouch for the fuel-cooled effect :-D 35mpg for about 35 bhp at the back wheel isn't great by any standards!
The smaller components in a bike will tend to dissipate heat a bit quicker (larger surface area to volume ratio), but bike engines also tend to be very compact, which means an effective lubrication and cooling system has to be designed in from the start.
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high-volume cooling systems to keep the temps down
Adding a high volume water pump and a large capacity radiator doesn't help. It is component temperature that matters.
This is especially true for diesels where heat soak is the limiting factor in sustained output.
Bikes have an advantage in that their engines run at very high RPM, so most heat is dumped into theexhaust, rather than the combustion chamber.
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Why is it then, that there aren't lots of these blowing up when driven flat out down the autobahns in Germany?
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Because most of them are big diesels and as I say ti's difficult to over-rev a diesel. And even at 120 mph (about as fast as most of them go unless the autobahn is deserted) the engines won't be flat-out.
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Looks like the consensus for my old N.A. plodder is to keep it serviced and not be shy of the noise pedal on the motorway. Excellent!
I never bother racing through the gears, it literally goes no quicker than just using the torque and changing up sensibly.
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Quite, but a good sustained blast at highish rpm for a few minutes does help blow out accumulated deposits, sometimes to the chagrin of those following you (for the first mile or so, anyway :-D
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Provided the diesels isnt chipped- thats is a standard engine there should not be a problem
I have done numerous long autobahn runs in "ordinary " cars at high speed without adverse effect.
Most cars are built to survive very heavy abuse that the majority of owners never subject them
Provided the car is standard and serviced as it should, long high speed journeys should not be a problem.
Just look at the number of high mileage cars that are still serviceable.
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Agreed. But it should be borne in mind that 70 hp will get most cars north of 100 mph.So the problem is largely a theoretical one.
But if you were to take a 180 hp 2 litre diesel to it's aerodynamically limited top speed and stay there for say 30 minutes, the engine would be toast.
Unless of course every truck, train, or aircraft engine builder has got it wrong...
Bearing in mind that Cummins/Caterpillar etc have a 30 year head start on turbocharged diesel engines over the automotive boys, my money is on the heavy duty crowd being right!
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So in theory, if I drove my diesel at max revs in third down the motorway, it would blow quite quickly?
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No. Truckers change down a gear or two when climbing hills to protect their engines. RPMs are not important-sustained heat is the killer.
For car use, flat out performance is rarely an issue.
But you won't find high specific output engines in large vans or pick-up trucks because there's a risk someone might actually use it. In cars peak horsepower is normally only used for bragging rights at the water cooler.
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I suppose even if you were able to run a modern high-output turbodiesel at max load for long enough -- for example at the MIRA banked test track or similar, the ECU would start taking protective measures like cutting boost.
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