Higher Octane Fuel?

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Tue 20 May 2003 23:45
Higher Octane Fuel? - nixontim
My Ford Orion 1.6LX handbook suggests that no advantage will be gained from using a higher octance fuel like Optimax?
I have read that no advantage will be gained becausse the engine managment system is not set up for this type of fuel?
Is this true? Is it worth me using optimax instead of normal unleaded and what benefits will i see?
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Wed 21 May 2003 00:14
Higher Octane Fuel? - SkyMan
In order to get any benefit from higher octane fuel you'd need to adjust the timing. I guess Ford don't publish the ignition advance to use with various octane fuels, so if you're feeling brave you could try it yourself, but if I were you, don't bother!

Some cars (is it Vauxhalls?) have a switch that tells the ECU which octane fuel is in use, whilst other cars have knock sensors so that the ECU alters the timing to suit the octane used.
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Wed 21 May 2003 00:21
Higher Octane Fuel? - nixontim
So are you suggesting that using Optimax for example will not be of any benefit and i should stick to normal unleaded? Will using Optimax be of no benefit whatsoever?
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Wed 21 May 2003 03:29
Higher Octane Fuel? - SkyMan
It would only benefit if Optimax had other additives that regular unleaded didn't have.

I'll give you an example:

My wife drives a 1.8 Toyota - Regular unleaded
I've got a 2.5lt Skyline - Super Unleaded.

The skyline's ECU has knock sensors and so adjusts the timing to match the fuel octane, therefore by running Super Unleaded I get better performance and MPG.

However my wife's car's timing is not controlled by the ECU and as its not a performance engine (as with your Ford engine - sorry!) we just use regular unleaded.

Bear in mind that I'm in NZ and regular is 91RON and super is 96RON (Shell) and 98RON (BP)

Jamie.
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Wed 21 May 2003 09:47
Higher Octane Fuel? - roscopervis
Why dont you go and try some?!
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Wed 21 May 2003 09:48
Higher Octane Fuel? - Pete F
You won't get any benefit from the higher octane. Assuming you have a catalyst car, then you can't change the timing anyway.
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Wed 21 May 2003 11:34
Higher Octane Fuel? - Jonathan {p}
Why can't a catalysed car have a variable timing? Honda and Toyota seem to be able create vvti and vtec engines which have variable timing!

Jonathan
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Wed 21 May 2003 11:39
Higher Octane Fuel? - TrevP
I think what he is asking is - will it make my car go faster?

answer - no.
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Wed 21 May 2003 12:08
Higher Octane Fuel? - Pete F
Jonathan
My answer meant that you cannot change the ignition timing to take advantage of the higher octane. This could perhaps be done by somebody like Superchips though.
Catalysed cars do have variable (valve) timing but this is nothing to do with changing the (ignition) timing in order to take advantage of a higher octane fuel than the manufacturer designed the engine for.
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Wed 21 May 2003 15:51
Higher Octane Fuel? - Nortones2
PeteF: I'm pretty sure I've read that the ignition timing is knocked back slightly on certain vehicles through the ECU (Audi?) if pinking thru' use of lower octane fuel is detected. In fact, they warn of slightly reduced power/increased consumption in such cases, e.g. if travelling outside the more affluent countries. So the converse may apply. Mixture control is cateerd for separately, by the lambda probe. Maybe our resident tuning expert can be more authoritative!
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Wed 21 May 2003 16:05
Higher Octane Fuel? - TrevP
Maybe, maybe not - but on an Orion?
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Wed 21 May 2003 16:24
Higher Octane Fuel? - Pete F
Nortones2
Yes the timing is knocked back automatically on the Audi by a knock sensor if detonation is detected. There is no knock sensor on the Orion and in any case we are talking about advancing the timing for higher octane, not retarding it for lower.
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Wed 21 May 2003 20:55
Higher Octane Fuel? - Nortones2
Pete: I agree, Orion has little going for it, but we were discussing wot Jonathan said! Japanese cars might, might, perform better on high octane fuel (as defined here) as they have 100 Ron at home. Therefore, some Japanese cars may run retarded here on super-duper, premium ready sliced, below par, Pratts best. Not to mention that all Fords pink, in my experience. Especially when old:)
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Wed 21 May 2003 16:42
Higher Octane Fuel? - Chas{P}
Jonathon
Why can't a catalysed car have a variable timing? Honda
and Toyota seem to be able create vvti and vtec engines
which have variable timing!


Those engines have variable valve timing.

Ignition timing will be controlled electronically by their ECU's.

HTH

Charles
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Wed 21 May 2003 22:33
Higher Octane Fuel? - SkyMan
My car has ECU-controlled IGNITION timing and a cat. Japan's super unleaded is (I think) at least 100RON (maybe more?) and so fresh Jap imports (like mine) that require super unleaded need to be de-tuned for the local petrol. On my car all you had to do was reset the ECU by disconnecting the battery. Once reconnected the ECU will use a pre-set advance and adjust it until the knock sensors don't pick anything up.

Having a cat convertor makes no difference, but with one you have to make sure the timing is correct (for that grade of petrol) or you might get unburnt petrol / hotter exhaust gases which will screw the cat up.

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