Race fuel / 100 octane

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Hi,

Quick question...... I have a AA3 300 and wondered if there was any benefit or pitfalls to running the 100+ octane fuels?

It’s not so expensive at the moment and wondered if it would benefit performance at all given that the car is tuned for regular pump fuel?

Any experience/ recommendations?

Cheers!

[autobackup]

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I have a 3.5R and it loves ECO Racing 100 - I have no empirical evidence but it definitely feels that it has more oomph in comparison with when I have to resort to 98.

As far as I'm aware it simply allows the ECU to 'advance' the ignition further thus giving slightly more power before the knock sensor is activated - I'm not sure that a modern ECU controlled engine is actually 'tuned' for any particular octane rating?

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Hi,

I guess the 3.5 has the k24 + maybe a newer ecu? I don’t know if my car can tell the difference ecu map wise...
It defo seems to like the high octane fuel but I can’t really judge, I don’t have many hours in it since I got it just before winter then fresh into the covid lockdown!

Hopefully the race fuel helps prevent knock, maybe more benefit in the summer?

Cheers!

[speedmachine]

Not an expert on our ECU, but all cars I have tunes (gt-r etc) where only able to detect and adjust down from the tune when or just before knock is being detected.
Never heard of a 98 tune that benefits from 102 octane, pretty sure this isn’t the case. With 98 tune and running on good quality 98, power output will be exactly the same as on 102 octane

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No - in fact my 3.5R has the K20Z4 engine fitted (as, in fact I believe, do most) and yes it has an uprated ECU.

- in fact, to my understanding, the K24 engine was fitted to very few R's as Ariel only started using it for AA3's after the K20 series engine became unavailable from Honda after it went out of production.

Very shortly after they started fitting the K24 the Atom 3 series was discontinued when the Atom 4 was announced!

My understanding of how an ECU works is that it automatically advances the ignition timing to the 'knock' threshold so by definition higher octane should result in greater advance?

- I would agree that a precise ECU map for the fuel used would be better for racing but, although the engine might run slightly hotter, using a higher octane rating - also providing the engine is suitable - should result in slightly more power in.a road going car!

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Aha - I mistakenly thought the 3.5’s used the k24, thanks for clarifying.
I’m going to continue using the good stuff whilst the going’s good price wise and see if I can spot the difference when is goes back up!

Cheers.