Discussion
I filled up my recently purchased 156 2.0TS with ordinary unleaded, more or less on automatic pilot. I later looked in the manual, which said I should use petrol with more than 95 octane but I'm not sure what that means - I checked on a Shell petrol pump but it didn't seem to give an octane rating. So the alternatives are to continue with standard unleaded, use ordinary Super (which I'm led to believe are rarely worth the extra cost) or to use Optimax. What do the rest of you use? Do you get noticeable performance/economy benefits?
My wife's 1.8 T'spark has a "knock sensor". I don't know if the 2 litre ones do but if so, it will just retard the timing a bit if it senses the engine "pinking". We have always used ordinary unleaded because she isn't bothered about going fast - she just wants to look younger! The car MIGHT go a bit faster with Optimax (or similar) but I very much doubt it will do it any harm on ordinary unleaded.
The igniton is set fro a minimum 95 octane, so 95 is fine.
Optimax is 98.6 octane, and WILL produce more energy, but you really need to have the ignition remapped specifically for this to gain maximum benefit. You will still get a smaller benefit using Optimax with the standard map though.
Squadra supply chips/remaps for high octane fuel- if your interested. The downside is that you then must use the higher octane fuel from then on- (at least on earlier models). Unfortunately I don't know if any of the remaps still employ the knock sensor to allow running on a lower octane fuel.
Optimax is 98.6 octane, and WILL produce more energy, but you really need to have the ignition remapped specifically for this to gain maximum benefit. You will still get a smaller benefit using Optimax with the standard map though.
Squadra supply chips/remaps for high octane fuel- if your interested. The downside is that you then must use the higher octane fuel from then on- (at least on earlier models). Unfortunately I don't know if any of the remaps still employ the knock sensor to allow running on a lower octane fuel.
Hi all - first post and I'm already disagreeing....
The octane value of a fuel tells is us its resistance to pre-ignition. It does not increase the amount of energy available from the the fuel. It does however allow us to increase the amount of ignition advance which in turn increases engine performance. The anti-knock sensor on modern engines picks up the characteristic accoustic signal produced and retards the ignition appropriately. Because of this it can be argued that the engine has to experience knocking before the sensor picks it up. So it should never be relied upon only used as a safeguard.
Sorry if I rambled a bit.
The octane value of a fuel tells is us its resistance to pre-ignition. It does not increase the amount of energy available from the the fuel. It does however allow us to increase the amount of ignition advance which in turn increases engine performance. The anti-knock sensor on modern engines picks up the characteristic accoustic signal produced and retards the ignition appropriately. Because of this it can be argued that the engine has to experience knocking before the sensor picks it up. So it should never be relied upon only used as a safeguard.
Sorry if I rambled a bit.
avocet said:
That seems odd!? I'd have thought the only point of having a knock sensor would be so it could just map its own ignition as it went along to run as much advance as possible at all times. Anyone know more about this? I'm just curious!
Don't know the Alfa set-up but many Jap motors are designed for their 100 RON fuel and so imports are very prone to knock. The ECU generally is set at the optimum timing for the fuel it expects and then ratchets back the ignition very quickly if knock is detected. What they don't tend to do is advance it as quickly when the knock has been eradicated as, as is pointed out elsewhere, to detect it it has to exist and that is bad. To get back to the original state of tune you normally have to reset the ECU.
Ah! That makes a lot of sense!
My wife has never used Optimax (or the like) in her 156 so does that mean I'd have to reset the ECU before giving it a tankful or I won't notice any difference? If so, how do I "reset" it? Is it simply a matter of disconnecting it (or the battery) for 30 seconds or so?
My wife has never used Optimax (or the like) in her 156 so does that mean I'd have to reset the ECU before giving it a tankful or I won't notice any difference? If so, how do I "reset" it? Is it simply a matter of disconnecting it (or the battery) for 30 seconds or so?
Ok- octane IS resistance to knock- but you get my meaning.
The standard map is not really optimised (why do you think there is such a boyant market for chips and remaps?). The standard map is more interested to achieve smooth running, and reliability from its conservative settings.
However, the higher octane fuel has a slower flame propagation, and produces a slower, kinder, more sustained burn. It will work better than the 95 octane, and is much kinder to the engine, but the standard map is better suited for 95 octane. Because of this, if you really wish to run high octane, you'd be better of with a remap specifically for this to gain maximum benefit.
The Alfa uses adaptive learning whereby it memorises the data of about the last 50 miles. That is why after the missus drives it, it DOES go slower. However, a sound thrashing will only ever allow the chip to be reset to within its programmed paramaters. Alfanige at Angel Tuning would be able to explain better than I, and I bet he'd be happy to arrange a demonstration- comes with a money back guarantee I seem to remember...
Or you could just disconnect the battery- but better just to adapt the driving style
>> Edited by Alfa Mad on Wednesday 30th March 22:29
The standard map is not really optimised (why do you think there is such a boyant market for chips and remaps?). The standard map is more interested to achieve smooth running, and reliability from its conservative settings.
However, the higher octane fuel has a slower flame propagation, and produces a slower, kinder, more sustained burn. It will work better than the 95 octane, and is much kinder to the engine, but the standard map is better suited for 95 octane. Because of this, if you really wish to run high octane, you'd be better of with a remap specifically for this to gain maximum benefit.
The Alfa uses adaptive learning whereby it memorises the data of about the last 50 miles. That is why after the missus drives it, it DOES go slower. However, a sound thrashing will only ever allow the chip to be reset to within its programmed paramaters. Alfanige at Angel Tuning would be able to explain better than I, and I bet he'd be happy to arrange a demonstration- comes with a money back guarantee I seem to remember...
Or you could just disconnect the battery- but better just to adapt the driving style
>> Edited by Alfa Mad on Wednesday 30th March 22:29
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