I wouldn't blame the lorry, I'd blame the highway authority for permitting lorries to use that route if they had a power:weight ratio that limited their speed that severely. Cars towing caravans are banned from the hill, but 40-tonne HGVs are allowed to use it; which has a worse power:weight ratio?
The problem is greater than that. It's more like a lorry going at 5-10 mph up that hill: difficult to find a gear that is suitable for driving a car that slowly up a steep hill.
I'm not familiar with lorries, but 50 seater buses (which weigh about 10 tonnes) rev around 1000-2000. I think from memory there's a green marker from 1000-1500 where you're meant to keep it, but I think it can go a lot higher, maybe 3000, for engine braking perhaps?
Things shouldn't be banned unless there's a very convenient alternative route for them. It won't kill you to wait for goodness sake.
A car will go happily at any speed up a steep hill. I'd probably use 1st for going 5mph. 10mph, 1st or 2nd would do depending how steep. Also, probably easy to overtake the lorry.
I remember seeing a video of an early diesel train where the rev counter in the cab was shown and that had a redline (except it wasn't red because it was black and white film!) at around 2000 rpm. So in scaling up from 1.5 to
2 litres in a car engine to whatever capacity is used in HGV and train engines, a much more severe max rpm limit is imposed. This articleI believe that marine diesel engines routinely run at a few hundred rpm - evidently they have very massive flywheels which prevent the engine stalling at around 800 rpm, as car diesels (and petrols) do.
They're huge on ocean liners and I believe the pistons are quite visible and you can see them moving slowly. Bound to be Youtube videos somewhere. It's one of those laws of physics, big shit goes slower. An elephant has a slower cadence than a spider.
My car (petrol) idles at 500rpm when warm (and 1000rpm when cold). It's a 1.6 litre non-turbo.
Pretty much yep
You should look at the redline on BIG - seriously BIG - marine diesels.
100RPM?
Not seen a diesel that big in person, but I have seen equally large steam engines, and they spun pretty slowly.
I have. I've walked on top of them. Push rods that I could have just got my arms around.
I never anything about a "special" force. Perhaps if you spent less time making up straw men and more time getting to whatever point it is you're trying to make we'd all be better off.
It couldn't hurt frankly.
Nicely cut and pasted. You an expert now? Feel free to explain which exact part of what I wrote in my hint was wrong and why you disagree with it.
Hmm, let me think, providing a pivot point for the turning force work on? Or maybe they're dancing the cha cha cha. Who knows eh? Maybe you think if the back wheels had no grip but the front wheels did the car wouldn't turn?
Why do I get the feeling your understanding of basic physics ended pre GCSE.
Sure - if the car went from a standing start at the bottom of the hill and didn't have any momentum that took it up part of it and it used the exact same gears for the exact same percentage of time going down as going up so the frictional losses in the gearbox and TC were identical. But yes, other than that your simplistic argument is spot on.
Not just that.
By building them like that they get a very long engine life and greater efficiency, both of which matter on vehicles that may be spending 18 hours a day on the move.
Andy
The only thing I am doing is trying to get you to explain this:
"If one pair are powering and steering (FWD) they're going to lose grip a lot sooner than if they were just doing one or the other (RWD) all other things being equal."
Well, it's a start. So are the rear wheels steering at the same time as the front? Or not?
Indeed. And this is also something that car manufacturers in the rush to small capacity, high pressure forced induction engines in cars in order to reduce fuel consumption by a few mpg are not coming clean about. The chances of these stressed engines lasting as long as a less stressed engine with larger capacity producing the same hp is slim.
If that needs to be explained to you then you're as thick as mince and there's little point continuing this conversation.
Fuck me you're dumb.
Again, non sequitur.
A 2 liter turbo diesl priducing 200bhp ar 4500 rpm is likley to outlast a 2 liter normally aspirated petrol delivering the same at 7500 RPM
Turbos mean you dont need to rev. And you can use low (native) compression engines that are far less critical about things like combustion chamber dimensions.
In addition the valve timing is far less critical to get adequate cylinder charge at higher RPM - and indeed higher RPM are not needed.
All in all a turbo engine - apart from the turbo - is likely to well outlast a normally aspirated engine on similar power output
Only if you build e.g. a YankTank big block V8 and accept fuel consumption in single figures, are you likely to get similar longevity.
Depends on what you mean by 'steering'
A car with FWD and no rear wheels will actually go round corners...
Maybe. But I was talking about engines of difference capacities anyway.
A turbo raises the pressure in the intake system which has to be built to handle it. And failure in the high pressure intake system and you're going to be parked up on the side of the road.
I'll take your word about valve timing, I don't know.
Not necessarily. Honda VTEC engines seem to last forever and take any amount of abuse tho Honda do tend to build their engines better than other marques it has to be said.
Which is exactly what I was talking about. Except with a big block you don't get all the extra complexity of a turbo or require high rpm.
Sometimes manufacturers try to squeeze too much performance out of an engine that is too small by increasing the turbo boost.
My Peugeot and my wife's Honda CR-V both have 1.6 turbo diesel engines. OK, the Honda is a bit heavier - not sure by how much. But the Peugeot has much better low-speed torque than the Honda, even though the Honda's engine is far more powerful and has greater *maximum* torque.
I sometimes forget this and try to take a corner or hill in third (as I would in my Peugeot) and find that the Honda has no pull at all even though the engine revs are about 1100. I can only assume that the boost pressure has fallen away to nothing (approaching in high gear with foot off throttle, so no combustion gases to spin the turbo) and it takes time to burn enough fuel to spin it up again. (*)
I've got used to it now: I work on the rule of thumb that when slowing down on the approach to a hazard where I'll need to accelerate away again, I use one (or even two) gears lower than I would in the Pug.
(*) Have manufacturers ever tried using an air reservoir, fed by the turbo, which can continue to provide high-pressure air during times when the turbo isn't pumping much air and can't really start doing so until the engine is burning more fuel (which needs the air that the turbo can't supply...)
Not much point buying a diesel if the low rpm torque is poor IMO. Compared to the price of a car the fuel consumption differences, and hence fuel running cost differences these days between petrol and diesel are fairly small plus with all the high pressure injectors car diesels have now they're not as reliable as the old type.
Yes, volvo have tried it.
Also I think they've tried electrically driven turbos too which to me sounds like a very expensive component that will fail very quickly.
Oh maybe half and atmoshere, BIG DEAL
And failure in the high pressure intake system and you're going to
No, you are not. Clouds of black smoke and a loss of power, but driveable
No, you get a lot of weight, a vile fuel consumption and a huge amount of bore wear.
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