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BP 102 FOR S4's


rjgreen4
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Because running optimax is exactly the same. You don't get instant oomph from optimax. You have to run a few tanks of it before it starts to have any effect. Cleans all the sh!t out and aids responsiveness.

My original statemtent, "A few tanks would see gains.. definately. " is not untrue.

Running a higher octane fuel over time has been proven to increase repsonsiveness after reverting back to original fuels.

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Hmm, not as I understand it - if your car isn't mapped (specifically with regard to timing advance) to take advantage of the higher octane fuel (standard UK mapping takes 95/98 into consideration) then where can the gains come from?

Standard maps focus on pulling timing back as a precaution, rather than pushing it forward.

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EMU's tend to be able to 'sniff' the octane levels and adjust accordingly, automatically.

Problem is the moment you have a full tank of Tesco's finest the EMU will re-tune accordingly.

OK for people willing to spend £11 a gallon, but who would do that, when it represents maybe 2% increase in response and engine power?

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[ QUOTE ]

EMU's tend to be able to 'sniff' the octane levels and adjust accordingly, automatically.

Problem is the moment you have a full tank of Tesco's finest the EMU will re-tune accordingly.

OK for people willing to spend £11 a gallon, but who would do that, when it represents maybe 2% increase in response and engine power?

[/ QUOTE ]

What he said.

If you have a higher octane fuel in your car, the ECU picks this up and adjusts itself to this fuel.

Anyhow, I'm not starting a battle, just sayin', lol.

I wouldn't pay £2.40 odd a litre. That's mental.

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Who knows...? Not me. I would imagine you could be right limited at 98, but then why would they develop a fuel at 102 octane if cars wouldn't benefit from it?

Speaking of ECU's, when you get a service, do they update the ECU to the latest revision??? My turbo seems to be kicking in at lower RPM's... was 1800rpm ish now 15-600?

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EMUs? crazy.gif

emu.jpg

ECU's don't 'sniff' petrol, although that sounds pretty cool, knock sensors detect knock and as a result the ECU retards your timing - which would be how it would detect 95 RON fuel. What I mean is that what is detected is not the Octane of the fuel but rather the knock that lower octane fuel may cause.

Hence, there has to be a ceiling value on the amount that the timing 'creeps' over time, otherwise the value would be limitless. For UK cars this will be set at or around 98 more so than 102. I'm saying your car can't "creep" up to the levels of timing required to take advantage of the 102 RON fuel and its resistance to detonate/knock.

On my S3 I have the Revo SPS3 which allows me to manually advance my timing - added to the fact that the remap already does this - meaning I can at least have a chance of taking advantage of the +/- 100RON fuel mix that I use.

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Higher octane wil presumably boost both HP and Tourque though wont it? Potentially by significant amounts (turbo cars)?

I wonder if they will start testing fuel?

Afterall it is potentially another way for them to get out of paying up....!!

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Not necessarily - that's what I'm trying to get at. The principal advantage of higher octane fuel is that it helps to prevent detonation. Normally, running more advanced timing (which gives a significant performance gain) leads to detonation/knock.

Higher octane fuel helps to prevent this happening (I'm on shaky ground on this bit) - I think its due to the way it prevents "pre-combustion". So....if higher octane fuel helps to prevent detonation/knock then you can advance the timing further to take advantage of this and that's where the performance comes from.

The other thing I'm getting at is that ECU's detect fuel "downwards" and only slowly creep back up again to a certain point. If you don't specifically tell the car to run X degrees of timing advance (i.e. via a remap or manual adjustment) the car won't know to advance the timing enough to take advantage of this!

169144-ok.gif

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[ QUOTE ]

EMUs? crazy.gif

emu.jpg

ECU's don't 'sniff' petrol, although that sounds pretty cool, knock sensors detect knock and as a result the ECU retards your timing - which would be how it would detect 95 RON fuel. What I mean is that what is detected is not the Octane of the fuel but rather the knock that lower octane fuel may cause.

Hence, there has to be a ceiling value on the amount that the timing 'creeps' over time, otherwise the value would be limitless. For UK cars this will be set at or around 98 more so than 102. I'm saying your car can't "creep" up to the levels of timing required to take advantage of the 102 RON fuel and its resistance to detonate/knock.

On my S3 I have the Revo SPS3 which allows me to manually advance my timing - added to the fact that the remap already does this - meaning I can at least have a chance of taking advantage of the +/- 100RON fuel mix that I use.

[/ QUOTE ]

Mollox is da man 169144-ok.gif

All this 'your ECU has to learn' malarkey ROLLEY~14.GIF

Do you guys know how many times a second a modern ECU will check for knock? Neither do I but I bet it's hundreds........ wink.gif

As soon as knock is detected the ignition will be retarded. So when you add your 98 RON the car knows instantly and will allow the most advance.

As Mollox says on a non race normally aspirated engine like the S4 I very much doubt putting anything higher than 98 will make a difference (I bet a re-map would allow more advance though). However on a tuned forced induction engine you will be able to take full advantage of the higher octane - More boost, more ignition advance and more power before the dreaded knock.

IIRC EVO had good results on 102 RON 'Race Gas' in their recent fuel test, using a 2.0t Golf GTi. So it would be interesting to know how much advance the manufacturers will allow.

BUB ECLIPSe.gif

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