Newbie question on engines

[pionte]

[quote="California Dreamin".so what is 97ron if not 4 star, same thing isn't it?

Martin[/quote]


yep... although in the UK they recon its closer to 98 RON. The extra performance comes from the fact that the higher grade RON fuel doesnt burn so fast allowing the ignition timing to be set further advanced .... IE for the spark to be set to start earlier before the piston reaches its top dead centre on it compression stroke.

If the timing is set too far advanced for the RON fuel used then full burn can happen before the piston has reached the top and the power from the expanding fuel and air expanding rapidly is trying to force the piston back down again before it has reached the top.... not good.

With modern petrol engines fitted with knock sensors , the ECU measures when the burn is taking effect and can adjust the ignition timing to compensate , it does this hundreds of times a second, so putting super unleaded in your fuel tank will give you performance/mpg benefits.

I dont think that any wasserboxer had knock sensors and the necessary to auto adjust ignition timing, so unless you manually adjust your ignition timing accordingly then no benefit will be felt.

The other benefit of the higher RON fuel was the greater amount of lead present... this lubricated the valve guides and seats, ask any classic Mini owner about this !

Anyone remember 5 star petrol !! Big old jags needed this

[mark]

essence au plomb super/ super 97 is good old leaded 4 star petrol. my timing is set as it left the factory. my bad...need to put more punctuation. the low to mid 30s where when driving normally carrying 2 passengers and all the kelt out using leaded fuel. the 80 mph was traveling from Rennes to Caen, super hot day, no wind traveling along the a84. this is the only time I have travelled at that speed for any length of time(I might have also left a t5 and t4 on the m1 but that was at a law abiding 70). I put the extra power and quieter running engine down to the lead in the fuel.
so instead of moving on im now waiting to be told how this didn't happen, it could have been the delirium of blue skies sunshine and no traffic on the road, I was on holiday and everything goes faster when your holiday, I was sat behind the wheel looking at the sat nav and rev counter or this is all a dream and nigella is down stairs frying the chips topless.

mark

Forgetting the revs for a moment, are we really saying Mark managed quote 'low to mid 30's' whilst driving 80mph on the flat ?

Mark also quotes high 20's on 97ron but then mentions 4 star and low to mid thirties......so what is 97ron if not 4 star, same thing isn't it?

Martin

[AdrianC]

essence au plomb super/ super 97 is good old leaded 4 star petrol.

The 97RON you're getting in France isn't leaded - it's sans plomb. There's (or, at least, was) a very tiny amount of leaded available for road use, but it's hideously expensive. Otherwise, France is subject to exactly the same regs and standards as the UK.

[mark]

jesus.......................christ I know what the ******************************************************** I was putting the tank, I went out of my way to get it as part of an experiment to see if there was any improvement. weve exchanged views on this in the past. the nearest garage to me sells lrp and I wanted the real stuff so while I had 2 weeks in the van using it everyday thats just what I did. and i will do the same next year in Cornwall

mark

essence au plomb super/ super 97 is good old leaded 4 star petrol.

The 97RON you're getting in France isn't leaded - it's sans plomb. There's (or, at least, was) a very tiny amount of leaded available for road use, but it's hideously expensive. Otherwise, France is subject to exactly the same regs and standards as the UK.

[California Dreamin]

Hi Mark....I don't know you and whilst I never knowingly set out to cause offense I realise that my abrupt & to the point replies can sometimes come over as a little course and abrupt.
Those that know me will tell you that my only intention is accuracy....well at least something approaching reality.
I absolutely love the image you conjure up, especially the Nigella bit wayhay ...but leaded fuel was being phased out in the 90's and a Europe wide ban came into force on Jan 1st 2000.

Martin

[AdrianC]

but leaded fuel was being phased out in the 90's and a Europe wide ban came into force on Jan 1st 2000.

Not _totally_, but certainly near-as-dammit. In the UK Bayford Thrust had a licence to sell a small amount of "genuine" leaded "4 star" - maximum half a percent of the total petrol sold.

I can't find anything to say that they aren't still doing so, but finding any vaguely recent information is not easy - and there's plenty of stories from a few years back of supply not being available for months or with no known date...
http://www.silverforce.co.uk/TB-UK/list.htm" onclick="window.open(this.href);return false; purports to be the "current" list of stockists, but no date to say how current that is. The "parent" page only has 2001 and 2002 dates on it, together with a fairly present-tense reference to the big foot & mouth outbreak! To add to that doubt, Bayford Thrust went through a big restructure a few years back, and took a step away from the petrol business.

LRP hasn't been around for roughly a decade, either.

[pionte]

not casting any doubts over anything anyone has said. I know that poeple dis believe me when I say that I get a genuine 93 mph showing on my sat nav from my hi top.

Just for info , there is a garage in Goudhurst Kent that sells 4 star petrol... advertised as such anyhow, IIRC about £1.90 per litre !! It is also a garage that sells classic 60 's style sports cars.

[mark]

I been out to the van and got one of my receipts I bought 42.8 litres at 1.739 /litre from relais de broceliande. 98 ron unleaded was about 1.53/litre. I have another one somewhere where I paid about 1.95/litre from garage just outside ranville.
sometimes my sarcasm get the better of me and no offence was meant. I found it quite easy to track down, but I was looking for it.

mark

Hi Mark....I don't know you and whilst I never knowingly set out to cause offense I realise that my abrupt & to the point replies can sometimes come over as a little course and abrupt.
Those that know me will tell you that my only intention is accuracy....well at least something approaching reality.
I absolutely love the image you conjure up, especially the Nigella bit wayhay ...but leaded fuel was being phased out in the 90's and a Europe wide ban came into force on Jan 1st 2000.

Martin

[mark]

I looked at that list and rang the hornsea garage and was told that the ''4star'' they had was lrp and the garage at aldbrough (sp) was a stockist but they were waiting for a delivery. both have hu post codes

mark

LRP hasn't been around for roughly a decade, either.