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1997 forester t/tb
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20 Posts
Discussion Starter #1
Has anyone tried any of the proprietary so called 'Octane boost' fuel additives...Thought about using one of these and just regular 95ron in the T/tb,or is it a recipe for dreaded 'Pinking'(detonation) probably no substitute for good 97-98ron fuel but in these days of thrift....????
 

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Official sf.org decal guy
2006 FXT
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12,516 Posts
I've used an octane booster (not sure which one) before a couple times when less than 93 (what ever the US uses for rating) was not available. If worked fine and I had no issues using lower octane fuel with the additive. It is quite pricey and does not add much in the way of octane. For what it does, it would likely be cheaper to use higher octane fuel. It is good to have on hand should you be tuned for a specific octane lever (as I am) and that grade not be available should you need petrol.
 

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none none
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9,011 Posts
A bottle of octane boost adds about 0.1 octane or less to your fuel. Not worth the money, better to get a drum of racing fuel.

and todd beat me to it! bah!
 

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Administrator
2004 Forester XT Premium 4EAT
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30,106 Posts
I hear toluene works well. At least that's what all those early STi owners were using here in the US 5 years ago before Subaru finally reflashed their ECU's.
 

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2006 Forester XT
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658 Posts
These booster additives are in no way 'thrifty' if you do the math.

If I were looking for a quick point or two of octane, I'd look to buying a gallon of Toluene or Xylene, usually sold in paint or hardware stores.

For octane purposes, toluene can be considered as '116 Research' which is the system you would use, being in the UK. Xylene is more variable, but would reliably exceed 124.......

The good 'doctorr' in this thread from a distant forum, a long time ago, said it right -
Octane booster Info/Questions - RX8Club.com

That octane booster stuff is just enough boost to meet the label's claims, and not in the least thrifty.

S
 

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1997 T/tb
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511 Posts
Does 97ron really make that much difference?

i never put it in my car, i have had japanese import cars for years and they have all run sweet on 95. dispite being told i will run into problems using 95, the only problem i seem to have is the government keep hiking the price up!
 

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Premium Member
98 JDM Stb Manual
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3,788 Posts
It will run but not be optimised, hard use on low octane fuel in a JDM will eventually cost ££££

Frazer however is the exception, saving himself £££££££££££££ lol
 

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Mad Englishman.
MY06 Forester STi 6MT
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4,158 Posts
It will run but not be optimised, hard use on low octane fuel in a JDM will eventually cost ££££

Frazer however is the exception, saving himself £££££££££££££ lol
I suspect his ECU would have adjusted to constantly retard the timing by now, so will be "safe". Means he will only be getting 90% (for example) of the performance available for users of V-Power.
 

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1997 T/tb
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511 Posts
I suspect his ECU would have adjusted to constantly retard the timing by now, so will be "safe". Means he will only be getting 90% (for example) of the performance available for users of V-Power.
I tried the 97ron from Texaco. i drove from Edinburgh to York. did plenty of quick overtaking on the crap parts of the A1, but wasnt convinced it was any more responsive than the 95ron so decided it was a waste of money.
my car has been running perfect ever since on the 95ron.

Apparently my old Opel Astra actually knew what fuel was put into the car. the ECU would either increase or retard the timing dependant on the fuel rating. surely subaru do the same?

I also own a eunos roadster, i have highly modified it, (supercharged) was also running jackson racing cold air induction kit. and numerous other induction mods. i get no difference using either 97 or 95 fuels, i have had it a long time now (10 years or so) so im pretty sure its safe to run 95 in it.
 

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Mad Englishman.
MY06 Forester STi 6MT
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4,158 Posts
Apparently my old Opel Astra actually knew what fuel was put into the car. the ECU would either increase or retard the timing dependant on the fuel rating. surely subaru do the same?
Certainly should do on most modern ECUs but it probably won't happen on one tank. From speaking with mappers the more modern subaru ECUs won't just whack up to timing advance straight away - they will slowly adjust the average upwards, so that what's going on is more average based. This is assuming the map on the car has got the appropriate settings to allow for this of course.
 

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Mad Englishman.
MY06 Forester STi 6MT
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4,158 Posts
I also own a eunos roadster, i have highly modified it, (supercharged) was also running jackson racing cold air induction kit. and numerous other induction mods. i get no difference using either 97 or 95 fuels, i have had it a long time now (10 years or so) so im pretty sure its safe to run 95 in it.
Have you run it on a rolling road or is this the impression you get between fuels...? What's it mapped for...?

Personally I reckon a frosty morning has the biggest performance uplift, as most of us on here have commented on before.
 

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1997 T/tb
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Have you run it on a rolling road or is this the impression you get between fuels...? What's it mapped for...?

Personally I reckon a frosty morning has the biggest performance uplift, as most of us on here have commented on before.
yeah the Mx5 has been on the rolling road numerous times, usually just to see what the latest mod has increased the performance by. never put the forester on the rolling road, just because i class this car as my "sensible" car!

might give it ago next time someone organises a dyno day!
 

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Mad Englishman.
MY06 Forester STi 6MT
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4,158 Posts
yeah the Mx5 has been on the rolling road numerous times, usually just to see what the latest mod has increased the performance by. never put the forester on the rolling road, just because i class this car as my "sensible" car!

might give it ago next time someone organises a dyno day!
Hampshire Scoobies did one jointly with Surrey Scoobies up at Surrey Rolling Road only 3 weeks ago :biggrin:
 

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1997 T/tb
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$1.90 per gallon????? If only! thought you guys were up to $2.50 per gallon now?

Just got back from Qatar..... 17p per litre! and you can haggle at the pump if you dont like the price!
 
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