Hybrid Cars

[The Natural Philosopher]

Yes.

[The Natural Philosopher]

No. There is a theoretical limit to how efficient a heat engine CAN get.

Its related to the ratio of combustion temperatuyre to exhaust temperature.

Generating plant goes to extreme lengths to condense the output working fluid (steam) down to extremly low levels of temperature to extract the most.

Short of puuting cooling towers on your car, or runnig them with sewater colling te exhaust pipes, the limit with average combyustion temperatures is around 30% thermal efficiency. Power stations creep over 50%.

Thats why thie 'hydrogen' cars are taliking fuel cells and alectric motors: They can be far more efficient in extracting energy from the fuel.

No, I am saying that state of the art stuff - which can be bought for under a hundred quid for a horsepower motor BTW - is already there up in the sorts of conversion efficiencies that are completely unobtainable from IC engines. Cooking grade motors are up around 80-85%. Even the worst mass produced shit with crappo ferrite magnets will do over 60%,.they are te equivalent of a lawn mower engine in cruduity..

wattch an wait.

Its not.

BUT te whole point is that te electric motors are so simple and cheap and light - that that ot comes out by istelf. You do not have to engineer an electric motor down in weight, its there aleready.

No you do not. Electric motirs have wlayws been vastly more efficient than IC engines for sound theoretical reasons.

IC engines have got beter by tuning te fuel air mixtures, and increasing peak pressures, but you cannot escape the laws of phsyics. Only if you go to extremely high temperatures with e.g. a gas turbine can you get efficenices even approaching 40-50%. Or fit condenser to the exhaust..

You can do all that in a generating set, but its TOO HEAVY in a car.

Its not. Abou 90% efficient. If you do it right

well I have him plonked, so I can't say what he said originally.

Ther are batteries in existence that will enable electroic cars to compete in performance and range with a comparable wieght of petrol powertrains...lets leave it at that..

However you need to do an overall analsyis of the whole vehicle power train- looking at one or another compnonet leaves a false impression. You are as guilty of that as Drivel.

No, I wouldn't be. NO IC engine will ever do 80% efficiency unless its combustion temperature is up around plasma temperatures or it has condensors on it to bring the exhaust down to absloute zero :-)

The practical limits of a very good diesel operated at its best is about

40%.

Do a google on 'enthalpy heat engine efficiency' and see what I mean

The fact that a power station can do more, is because of thse massive condesors.

I am not saying that an electric car would result in a huge change of overall burning of fossil fuels..BUT if we take the fact that nuclear electric generation is likley to be the most prctical way foward in the next few decades, what is not relevant is to use that electricity to generate chemical fuel, then burn that in IC engines. Its extremely watseful. That may not matter in terms of actual overall carbon balance - nuclear constriucted hydrogen will niot affacte the carbon one way or another, and its probably possible to make even diesel from carbon dioxide water and enough electriity - but the cost of so doing is likley to far exceed teh cost of simply having vbattery cars.

[Doctor Drivel]

Timmy, it is. This groups has it in abundance. Richard Cranium is clearly an obvious case.

[Doctor Drivel]

"Dave Plowman (News)" through a haze of senile

** snip more senile drivel **

[The Natural Philosopher]

Its been done already. Sadly I lost the link. I'll look for it an d post it if I get time.

300 miles range, 160mph top speed and 0-60 in sub 6 seconds.

Although I grant you the range on the passat is likley to be greater.

Rubbish. 3 years for some decent concept car, and ten for production.

I've done the sums. Unlike Drivel I AM an enginneer..fully qualified.

[The Natural Philosopher]

Oh sure. Very few prodution cars exceed 100bhp/liter. Certainly not diesels.

My supercharged V8 4 liter jag dpes not crack 400bhp.

Racing engines can crack it to be sure...and especally 2-strokes.

Current F1 enfgines are cranking out 850bhp on 3.5 liters.

At 18,000 RPM using titanuium conrids and pneumatic valves....and about 3 miles a gallon

[Doctor Drivel]

Richard Cranium here is in cloud cuckoo land. he obviously has never driven of heard a diesel car.

temperature.

I should think so. Keep me plonked.

Mr Cranium can't understand that.

Nonsense. I was the one who said you compare the energy density of each (usable energy as 70% is lost in an IC engine) vs. the weight of each. The lunatics could not undestand something so simple.

Richard Cranium can't figure that out. Don't confuse him.

[Doctor Drivel]

transmission and

You are not. You are from a snot.

[Doctor Drivel]

Don't tell Lord Hall that. Leave him in ignorance.

[The Natural Philosopher]

Here is one car you can actually buy.

200bhp, sadly limited to 100mph but fast...to get there,.

and 100 mile range. Albeit at 60 mph :-(

that this is with LEAD ACID batteries.

You should get three to five times the range at least on lithium polymer, for the same weight.

But of course it will not be $3000 a set - more like $300,0000 currently :D

It uses 28 x 50Ah x 12v batteries..I make that about 18KWh...which is close to what I predicted - 30KWh for 300 mile range. They are using 18Kwh for

100 miles..

[The Natural Philosopher]

And the Tzero equipped with Lithium Ion (not the most up to date yet) scored very well in a green car competition...260 mile range at least

Also an effective 153mpg, though the way this is calculated seems weird. And does not take into acount charge, transmisson or generating inefficiemnces I think.

you can say what you like, but evcen allowing for exagerration by te makers, this is impressive.

Ypu can say again, all you like that this vehickle won;t do as much range as an airbus, carry as much load as the queen mary, or cost as little as a bicycle, but the fact remains that the vast majoriry of domestic car journeys would be utterly seved by a car that you charge overnight, and drive around by day up to 200 miles.

Not a sports car like this - more of a sort of small to medium people carrier type shape. A town car in fact.

[vortex2]

Like this you mean?

[Chris Bacon]

Litre.

Anyway, there's absolutely no reason that they should not exceed

100BHP/litre, is there?

[Dave Plowman (News)]

I'm not disagreeing with that, but you've got to look at the whole picture. The efficiency of the actual motor makes little difference if the generation/storage of the power needed is wasteful.

Trouble is that with 50% generator efficiency and then storing that electricity to drive a 90% efficient motor you're getting dangerously close to even the 30% of an IC engine using the same fuel. Add in the heating required for much of the year for the inside of the car and it can become worse in practice.

Again, the most efficient way of charging a battery may not be the best way for long life. And these type of batteries will always be expensive - perhaps half the total cost of the car.

Well that was what I was replying to. It's as well to read that first. ;-)

I'd be willing to bet there aren't. They'll fiddle all sorts of things to get this result. Extra low friction tyres and bearings etc. Low vehicle CD and weight. Then compare it to a bog standard car - the worst they can find, probably too.

I'm trying to analyse the whole use of energy for a vehicle, likely running costs and life. You should try that too. ;-)

[Dave Plowman (News)]

Most of the BMW 'M' series engines manage it - without forced induction.

[Dave Plowman (News)]

You seem to be having problems with your keyboard again. Or perhaps it's just your brain cell giving up? No matter.

The Peugeot 206 1.4HDi beats the Prius in the combined cycle and costs less than half the price. Perhaps if Wicks sold it you'd be interested? Or if it were badged PPPro?

I have a neighbour with a new BMW 535 auto. One of the nicest cars I've ever driven. Pity about the looks, though.

[The Natural Philosopher]

Cost Fuel efficiency. Tractability. Noise Pollution Fuel.

Racing engines are optimised towards peak power to weight and peak power.

Car engines are optimised towards low production cost, fuel efficiency and tractability. Theyhave to meet noise and pollution standards. They have to run off pump fuel. F1 engines may all run on the same 'lowish octane fuel', but its not what you buy at Tescos..

You may fancy driving round town with a cosworh F1 engine up your arse, but I don't.

[Matt]

FFS it's nothing like a "Cosworth F1 engine up your arse" ! a 90 year old could easily drive an off the shelf production engined vehicle with a perfectly tractable 120bhp per litre engine down to Tesco's, do the weekly shop and fill it up with petrol at the same time (95 octane unleaded) . As far as emissions are concerned they kick out much less than your 4 litre Jag.

[Matt]

and your point being?

[Matt]

Oooh I can hardly wait :-) It's just like Christmas, you wait 10 million years for a decent battery system and all of a sudden one appears from nowhere.

and the fact it has space for 4 or 5 adult size humans and a boot you can fill with something more than a collapsible toothbrush.

Ditto, but don't forget the 48.7mpg "battery" :-)