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Old 11-09-2013   #16
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

I use 99 octane in my turbos, too.

Now I remember, 5th Gear did do some dynamometer tests of various fuels, which may be on the Net somewhere. Essentially they found that engines designed for 95 octane made no more power on 99 octane than on 95, while (some) engines designed for higher octane fuels would run on 95, but lost power on the cheap stuff. (Don't try this on cars where the ECU is unable to adjust the ignition timing to compensate, or mahem will occur.) From memory, they used a late Imprezza (it would destroy an early one) and something awefully posh.

Although associated with performance, high octane fuels are actually slower burning than low octane ones. This becomes very apparent with super high octane fuels like Methanol, Ethanol and LPG which require a lot of ignition advance to get peak combustion at more or less the right time.
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Old 11-09-2013   #17
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by fingers99 View Post
I use 99 octane in my turbos, too.

Now I remember, 5th Gear did do some dynamometer tests of various fuels, which may be on the Net somewhere. Essentially they found that engines designed for 95 octane made no more power on 99 octane than on 95, while (some) engines designed for higher octane fuels would run on 95, but lost power on the cheap stuff. (Don't try this on cars where the ECU is unable to adjust the ignition timing to compensate, or mahem will occur.) From memory, they used a late Imprezza (it would destroy an early one) and something awefully posh.

Although associated with performance, high octane fuels are actually slower burning than low octane ones. This becomes very apparent with super high octane fuels like Methanol, Ethanol and LPG which require a lot of ignition advance to get peak combustion at more or less the right time.
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Old 12-09-2013   #18
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Or .
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Old 12-09-2013   #19
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

All standard (and by "standard" I mean unmodified) Cinqs & Seis should run perfectly on 95RON and show no improvement on 99RON (and could possibly run worse as they have no knock sensors).
However I suspect the ignition timing is slightly out on my 899 Cinq and that combined with the slightly higher compression ratio from needing the head skimmed means I get pinking on 95RON but it runs perfectly on 99RON (Tesco 99 most of the time).

I know I should just adjust the ignition timing, but I suspect the screws will snap and just using 99RON is a lot less painful...!
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Old 12-09-2013   #20
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by David C View Post
All standard (and by "standard" I mean unmodified) Cinqs & Seis should run perfectly on 95RON and show no improvement on 99RON (and could possibly run worse as they have no knock sensors).
However I suspect the ignition timing is slightly out on my 899 Cinq and that combined with the slightly higher compression ratio from needing the head skimmed means I get pinking on 95RON but it runs perfectly on 99RON (Tesco 99 most of the time).

I know I should just adjust the ignition timing, but I suspect the screws will snap and just using 99RON is a lot less painful...!
Is that possible (adjusting the ignition timing) on an 899?
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Old 12-09-2013   #21
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by ycming View Post
Is that possible (adjusting the ignition timing) on an 899?
not easy e.g. move the TDC sensor...

but he should not be pinking after a skim even on 5% ethanol cut petrol, may be bad headgasket?
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Old 12-09-2013   #22
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by fingers99 View Post
But it's hardly a double blind test, therefore has no objective relevance. Indeed, I know of no objective tests which prove any performance increase with vehicles designed for 95 octane. (And you'd certainly expect to see them!)

Sorry to pee on your delusion!
I don't think that I was claiming anything other than subjective impression , consequently am bemused by your attitude .






But ultimately couldn't give a monkey's , frankly .
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Old 12-09-2013   #23
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by dr pinkie View Post
Er - sorry to rain on anybody's parade , but I have run both my present 2000 Sei and previous Chinc (and previous Honda nx650 'bike) on super only , Tesco 99 for preference , except when not available , and you certainly can tell the difference in terms of throttle position , sprightliness , and ability to climb hills .
Just sayin'
don't see the word subjective or opine?
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Old 12-09-2013   #24
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

::

Some kind of petrol head Creationist, perhaps?
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Old 14-09-2013   #25
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Suggest you two keyboard heroes re-read the second line of my reply for true enlightenment .
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Old 14-09-2013   #26
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by dr pinkie View Post
Suggest you two keyboard heroes re-read the second line of my reply for true enlightenment .
What's that

Quote Quote:
Just sayin'
or

Quote Quote:
But ultimately couldn't give a monkey's , frankly

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Old 14-09-2013   #27
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

All I can add is that the one time I accidentally put Shell V Power in the Sei I got the highest mileage I've ever got out of a single tank - 362 miles. However even if this was repeatable, the increase in MPG would be entirely negated by the higher cost....

As I'm a bit sad I do actually keep detailed MPG records, over about 30K miles we have averaged 41mpg. It continues to creep up slightly as I am doing more motorway driving now, the car is the closest to being "new" that it has been since it was, well, new, and for the first month we had it the tank was leaking.

45mpg seems like a reasonable figure for a well maintained standard Sporting.
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Old 14-09-2013   #28
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

45 seems ok for normal ish driving, a cento can do much better though although i find it really hard to drive one in an economical way.. Also i have even even been in a mpi one let alone run one for a bit so can't comment there, and nor do i ever really keep track of how much i use personally - but i do know that my cinq over the stanford hall weekend did about 350 ish miles on 1 tank of regular fuel even though it wasn't running well for alot of the time. But I have a P60 engine in that so not really a fair comparison either.
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Old 16-09-2013   #29
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

899 made no difference
1.2 16v - high octain higher mpg and a few flames standard octain less mpg and no popping/flames
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Old 16-09-2013   #30
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Re: Good petrol? Bad petrol? (for a 2001 Sporting model)

Quote Originally Posted by slugworth1987 View Post
899 made no difference
1.2 16v - high octain higher mpg and a few flames standard octain less mpg and no popping/flames
Sadly/thankfully, I don't get any flames from my Punto...

...but I certainly get better economy (fewer pence per mile, as well as higher miles per gallon) with super unleaded (as I've said elsewhere... -- sounding like a broken record...).
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