The matrix collapsed. But it really did totally collapse. At the end of the return leg, it wouldn't go over 30. (Yes you're right-melting a ceramic would be a hell of an achievement!)

I wouldn't have thought that was possible in a closed-loop fuelling system ...

I was surprised but not once I thought about it? Don't forget, the hottest flame is a stoichiometric one ie closed loop. Combine short gearing pushing the RPM up to about 4500-5000 at 70 mph +10%+1+X, and only a single exhaust valve and the EGTs were probably over 900C. Turbo petrols run rich to keep temperatures down and often EGTs drop at full throttle.

It might have been frequent lifting off that did it (no overrun fuel cut off). Interestingly, the engine was not distressed, no audible pinging, no overheating, no loss of power indicating heavily retarded spark timing. Compression check was fine-no burned valves. It wasn't a MAF/lambda problem either. Only the cat wa replaced and it's sailed through emissions ever since.

How much soot & particulates is that old Renault generating ? The MOT figures you quoted didn't mention the worse offenders of older diesel engines (i.e. soot & particulates ).

Not many I wouldn't have thought, with unthrottled's car being a petrol.

How much soot & particulates is that old Renault generating

Less than a Euro V diesel, Mike. Like all port injected injected petrols, soot and PM will be negligible. CO and HC emissions will be high from a cold start though.

NOx emissions will be lower too.

As the last few days of panic petrol buying have shown us - people are stupid. This is the general public, an overall IQ of 37 so Governments need to keep that in mind when making policy. Its all well and good promoting personal responsibility but 99% are incapable of it. People act like children so need to be treated as such.

A car is a complicated thing and most people dont understand it. People don't understand about DPF's either and I blame dealers for not explaining it to customers. The fact is if you push people into diesels with high fuel prices then millions will buy cars which don't suit them and suffer problems, thats fact. I'm more interested in fact than 'personal responsibility' rhetoric.

Asda smart price. There's a Shell garage nearby that (almost) price match their standard 'fuel save' petrol, but after two tanks I couldn't see any improvement. Asda's pumps pump much more quickly than the Shell ones, so that swung it for me!

edit-It's interesting that you bring up the diesel comparison regarding emissions. Even pollution specialists can't agree on the whether petrol or diesel is 'cleaner' in terms of trace pollutants. There's a huge row about PM from diesels. There's a school of thought (which I'm in) that thinks that the regulators got it wrong with soot, and that old diesels might be less damaging to air quality than new ones!

Edited by unthrottled on 30/03/2012 at 13:54

You must be more sensitive than me, but then I like the smell of petrol!

It should be borne in mind that looks can be deceptive. The visible smoke from an old diesel is comprised of relatively few big soot particles that fall out of the atmosphere in minutes. But the new diesels emit large numbers of small partciles that linger in the atmosphere for a week or more. that's why I think they got it wrong.