Dieselgate

The new DOT report on "real world" emissions makes interesting reading and basically confirms what we've all known/suspected for ages, namely that real world emissions are vastly higher than test cycle ones.

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Disappointingly, they've only tested a euro 6 VW and not a euro 5 one which are the ones affected by the "cheat device" as I understand it. I'm disappointed as I think the question that we all wanted answered was "in real world emissions, are VWs any worse than average?".

Based on the the only figure I can find on wiki, the euro 5 VW seems to be dead average in real world emissions at 620mg/km of NOx.

Yes, VW were very naughty but it seems in real world emission terms, no naughtier than the rest.

Tim

Reply to
Tim+
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The whole 'official figures' thing has always been a scam, especially as regards MPG. So should really come as no surprise that emissions have been fiddled too.

The other obvious one is CFL and LEDs etc being a 60 watt or whatever equivalent. When anyone other than a blind man can see they're not.

Reply to
Dave Plowman (News)

The real scam is that I've got an Osram "12 years" CFL bulb that failed last year. It was installed in 2009 so they own me 1/2 of a bulb.

Who keeps a receipt for a £4 bulb 6 years after purchase?

Reply to
Peter Hill
[...]

Getting hilariously OT even by u.r.c.m standards, but I have had several expensive led lamps fail within a year or so. It would appear the electronics are at fault, rather than the leds. The circuit breaker usually trips. It seems a particular problem if they are used in enclosed fittings, even where they are sold as suitable for such use.

Chris

Reply to
Chris Whelan

I had one fail - a 3GU5WW - about a year after purchase. Given that I bought it through the business I went back to the supplier (Denmans Electrical) with the receipt and complained - and was immediately given a replacement.

Since the device must use a switch-mode power supply to get from 250vac to about 3.3vdc per LED in a small space with minimum heat generated, I'm not surprised that they fail.

Reply to
Graham J

Then what about bhp figures? With turbocharging now getting more common, bhp can be almost anything. My 200bhp old Saab seems paultry these days, but it has APC mode which can go beyound the quoted output. As I understand it, in US car manufacturers are allowed to quote peak bhp.

Reply to
johannes

Um, don't all manufacturers quote peak BHP? What other figure would they quote?

Tim

Reply to
Tim+

Yes. It's the same problem as CFLs. A pendant mounted lamp allows the heat from the light source to rise into the electronics above. Mostly a problem with higher powered devices. And the life of an electrolytic capacitor depends very much on the temperature it runs at - the higher, the shorter its life. Use the lamp outdoors only - or in a table lamp etc where the electronics are usually at the bottom, and they are more likely to last their claimed life.

Reply to
Dave Plowman (News)

The CFL I had fail at 1/2 life was a candle style with the electronics at the the bottom. The other 3 I got at the same time are now at 7/12 life.

Reply to
Peter Hill

I have visions of 90s car head unit adverts now... in the laminated book of dreams.

Reply to
SteveH

Well there are 2 Brake powers and Indicated power. Nett brake power, all installed ancillaries are driven by the engine, water pump, fan, alternator, A/C drive, power steering. Gross brake power, no fan, external water pump, no alt etc. Only power loss is cam and oil pump drive, this used to be be what USA makers claimed (and I think some may have had external oil pumps to bump up the gross even more). Indicated, a pressure tapping is made into the cylinder. Indicated power = indicated mean effective pressure x stroke x piston area x engine speed (rad/s) x number of power strokes per rev / 2 pi.

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For road use peak power demand is infrequent, most people drive on peak torque and use about 50-60% of peak power. Peak power comes with high rpm and a lot of noise, with quite fierce acceleration that deters most people from using it. For a large section of drivers the performance it unleashes is scary but they won't accept an engine that only produces the power they actually use as that would require revs and noise.

Electric cars quote the PEAK motor power but can't sustain it. They can go "lame" with not a lot of thrashing.

There can be a significant de-rate for continuous power, especially in range of rpm that peak power is maintained. This would be very disappointing on track testing where peak power is demanded everywhere except in braking zones. Perversely a cold lap will be faster than a hot lap as once the electric motor is hot it can't make the power it does cold.

McLaren E-motor is rated at 130Nm 500-9000rpm and 120Kw 9000-17000rpm peak. Continuous the torque is reduced to 105Nm at 500rpm and drops with increasing revs. Peak power is no longer spread over a nice fat 8000rpm band, with maximum of 115Kw at 15000 rpm appearing to be only a small

5Kw (4%) reduction, at 9000rpm it's only capable of 90Kw 3/4 of the peak. It degrades to a torque curve similar in shape to to big V8's, only much reduced and has the attendant sharks fin power curve.

Power / torque curves under Images/diagrams on this page.

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This changes the available acceleration curve so while for peak rated output a 3 speed would be adequate it needs a 5 speed for track performance. When run at higher power (not sure how, more volts?) for Formula-E it needs a 7 speed gearbox.

Most electric cars that are available (or soon to be) have a fixed reduction gear ratio. This usually results in a limited top speed. Nissan Leaf has 80Kw/108bhp, this power would normally be good for a speed over 100 mph but it runs out at 93mph. Tesla S has power to go well over 150mph but runs out at 130mph unless in ludicrous mode. Chevy Bolt will be limited to 93mph but 150Kw (200bhp) from an IC engine would be good for 140+mph.

McLaren E-motor at 26Kg is light for the 120Kw output so may be more badly affected. While the Nissan Leaf motor is 80Kw and 50Kg, there are no reports of noticeable reductions in power under continuous demand.

5 speed gearbox that can take 120Kw weighs over 40Kg. A 5 speed box incurs a massive increase in oil churn power loss over a 3 speed as there are 2/3 more gears dipping in the oil. This results in a 7% drop in maximum speed.

Peak 3 speed v's continuous 3 speed.

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Peak 3 speed v's continuous 5 speed.
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Reply to
Peter Hill

I have found cfls to last about three years in outdoor use, turned on all darkness hours, so around about 8,000 hr life. Make seems unimportant, although they are all known brands. Incandescents lasted around 1,000 - 1,500 hours. Now leds are more sensibly priced I am swapping to those. Screwfix are selling boxes of five ordinary shape bulbs 8.5 watt for ten pounds, so swapping those for the twenty watt cfls will pay for themselves in around 6 months.

Reply to
MrCheerful

You were unlucky.

Philips 11w PLC Electronic CFL Purchased 27/3/91 cost me £13.90. I was keen then working out the energy saving vs. install cost, so scribbled down the receipt details.

Bulb still worked when removed a few years ago.

So 20+ years service, but infrequent use being a porch light.

Reply to
Adrian Caspersz

Yup - so kept good and cool. It's those indoors which get hot which don't last their claimed life.

Reply to
Dave Plowman (News)
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Some turbo cars are set up up to allow increased boost for ~20 sec to help e.g. overtaking, but time limited to protect the engine. I saw somewhere that US dealers are allowed to quote his peak power.

Reply to
johannes

The Tesla S can manage 0-60 in 2.8 secs, but only once, then a ten minute cooldown, then iirc a half hour break after that. So yes, it has

600 hp available, but not for very long! But I would still be very keen to use one on a few day trial.
Reply to
MrCheerful

At least it won't be stolen for use as a getaway car, then.

Reply to
Dave Plowman (News)

I have seen a few Tesla S om M4. A red and a Blue. The red one joined at J6, then moved up on motorway at UFO speed.

Reply to
johannes

I was waiting at a traffic light crossroads on my bicycle, and watched one cross from standing. Quite a thing to watch something that size move so quickly - and in silence.

Reply to
RJH

Never really a problem to get an electric vehicle to have a good turn of speed or decent acceleration. All down to design. The far more important bit is range - and overall running costs per mile.

Reply to
Dave Plowman (News)

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