OT: Driving electric cars in winter

[NY]

I've never encountered a gearbox that coasts - if by that you mean it goes into neutral with the engine idling (*). That probably uses more fuel than leaving it engaged with the wheels: an idling engine needs a token amount of fuel to keep it revolving at idling speed, whereas an engine that it on over-run (wheels keeping the engine turning) can shut off the fuel completely.

I've seen this with the instantaneous fuel consumption gauge on my car's trip computer. Press the clutch while going down a gentle hill and the consumption decreases to about 200 mpg while the engine is idling, but release the clutch so the wheels keep the engine turning and the consumption decreases still further to a nominal 999 mpg as the ECU cuts off the fuel altogether. Of course, set against that is the fact that the car won't travel as far before you need to put your foot back on the power once the hill has levelled out, because of the very slight engine braking even in top gear. And the amount of fuel saved will be pretty minimal, I'm sure.

(*) I realise that coasting or free-wheeling is standard on crankcase-scavenged two-stroke engines, because a fast-revving engine with no fuel going into it means the bearings will not be getting much lubrication. I presume that two-stroke cars have heavier-duty brakes to counter the fact that you cannot use engine braking on a steep hill and must rely entirely on disc/drum brakes.

[Tim+]

Two-stroke cars must be getting a bit thin on the ground now surely? ;-)

From memory, early Saab 93, Wartburg Knight and Trabant. Any others?

Tim

[NY]

Some Skodas. I sometimes got a lift to school from a friend's mum and she had a green Skoda with very hard plastic seats with a deeply-embossed pattern that left marks on your legs for several hours afterwards! I can remember the characteristic yowl of the 2-stroke engine and the smell of oily exhaust which somehow found its way into the car even though the engine was at the rear.

I never understood why 2-stroke engines were built with crankcase scavenging rather than having a separate pump, driven from the crankshaft, to blow the mixture into the engine. More expensive that way, but you avoid the twin problems of horrible oily exhaust and the need for freewheel instead of engine braking on hills.

I wonder how long motorbikes and chainsaws will be allowed to continue having 2-stroke engines before the emissions regulations prohibit them.

[Dave Plowman (News)]

I'll say it once again. There is a strict relationship between BHP and torque. It would be impossible (or pointless) to make the first engine you describe.

If it has good torque between 1000 and 2000 rpm which then falls off, if will not have the same peak bhp as the one with the torque at the higher revs.

[The Natural Philosopher]

The only point of a 2-stroke is to get more power from less and cheaper engines.

[T i m]

If you can accept a bubble 'car' (often a Tricycle) as a car then my Messerschmitt KR200 has got a single cylinder 200cc Sachs 2/.

Another I learned of from the telly the other day was the 'FSO Syrena'.

We only have one 2/ motorbike now (MZ), a 2/ moped (Honda Express), a

2/ Yamaha outboard motor, a 2/ generator and daughter loves her 2/ chain saws and gardening gear. ;-)

If you like the smell of a 2/ you can now get a 2/ scented candle. ;-)

Cheers, T i m

[Dave Plowman (News)]

You've mentioned the reason. Cheap to make.

Commer trucks used to make a supercharged two stroke diesel in the '50s.

[T i m]

There are already 'catted' chainsaws out there but I don't know if that makes them 'green' enough to be considered 'clean' by modern standards?

Cheers, T i m

[Tim+]

And they sound pretty cool. Wouldn't mind my car making this noise. ;-)

Tim

[Davey]

My first car was an AC Petite, with a single cylinder Villiers. 9 bhp! It did 55 mph, once, downhill, following wind, etc.

But I can truthfully say that my first car was an AC, which sounds great as long as nobody asks which model.

[Dave Plowman (News)]

They also had a much better turn of speed than the average truck from those days.

Because of that they were chosen to take fish to London from Aberdeen. Whole fleet of them. They cut a few hours off the journey compared to Leyland, etc.

You'd have thought rail ideal for this. But transferring the load at either end plus the higher cost made road better. Long before motorways.

[Dave Plowman (News)]

Autos have come on a long long way from the days of US gas guzzlers. It's perhaps the main reason GM lost their lead as arguably the best auto maker. ZF realised that a 5 speed auto had many benefits over a 3 - mainly in terms of fuel consumption - but also in performance with a smaller more efficient engine and the high speeds allowed in Germany.

But of course these days, US autos are multi ratio too. Just took them longer to get with it.

As often happens, many seem to base their views on autos from experience years and years ago.

[Muddymike]

I missed the start of this thread but would like it known that my Diesel/Electric Peugeot proved itself very capable on the ice yesterday morning. It climbed a local hill that had defeated many normal cars.

Mike

[harry]

My (electric) car has a device to remotely turn the heating/AC on while the car is parked. No engine to be run of course. So quite legal.

[harry]

Mechanical power is the product of torgue and rpm. You can have no power generated without both.

[T i m]

I had 70 out of the Schmitt under similar circumstances. ;-)

Yup, could be a Cobra etc .. ;-)

Cheers, T i m

p.s. Mate bought a Cobra replica and because I had a towbar (?), he asked me to collect it with / for him. I don't know how many times heavier it was than my 2L Sierra Estate and I'm glad we didn't have to go very far. ;-(

[polygonum]

Why would you take fish from London to Aberdeen? I thought they had lots of fish up there. :-)

(Like stories of the "milk train" being the first train down from London. All those herds of cows across the city! First down train was often the paper train, first up train likely milk.)

[bert]

Only if you live in the south.

[polygonum]

The logic applies even if you replace London by Glasgow.

[Vir Campestris]

Pointless or impossible? Really?

AKA

is an Iveco truck engine. Peak torque between 900 and 1400 RPM, peak power between 1500 and 1900. I'm sure they'd love to widen the curve, but they obviously need the low-down grunt for efficiency. There's a more than 2:1 ratio between the top of peak power and the bottom of peak torque, so it should be quite easy to drive too - except that 500HP is probably pulling 38 tonnes.

Now that is proof that you can build an engine with peak torque that low down. As TNP points out, my two hypothetical examples would drive exactly the same - given different ratios in the gearbox.

If you are that convinced that torque matters (the Iveco is putting out about 1750NM) then why is it cars with the same body, same power output, and radically different torque numbers have similar performance figures?

Andy