BM3 91 vs 93 octane on Aussie fuel

[M4_Johnnys]

To anyone who has bootmod3 in Oz, has anyone ran stage 1 tune 93 octane? I run BP 98 (is there better?) but I've heard that tune knocks a bit on our 98. I've just installed the 91 tune for now but keen to hear what people have done? Car is stock.

[SE7EN335]

Originally Posted by M4_Johnnys

To anyone who has bootmod3 in Oz, has anyone ran stage 1 tune 93 octane? I run BP 98 (is there better?) but I've heard that tune knocks a bit on our 98. I've just installed the 91 tune for now but keen to hear what people have done? Car is stock.

91 octane is FAR smoother! The 93 octane has quite a lot of timing corrections. Its because Aussie 98 Fuel is not actually 93AKI, its around to 91.5-92 AKI.

[RevNev]

Our 98 needs 10% Toluene added to make use of a US 93 octane tune unfortunately.

[robbo mcs]

Originally Posted by RevNev

Our 98 needs 10% Toluene added to make use of a US 93 octane tune unfortunately.

or 20% E85

[M4_Johnnys]

Looks like a custom tune it is then!

[thiscarlife]

Hey guys, just a question, I've already got the 93 octane stage 1 tune. Are there any negative impacts to the car if i keep running it instead of switching to 91? Ceebs to pay another 50usd just for another ots map. Will switching to the 91 tune help gain more power?

[SE7EN335]

Originally Posted by thiscarlife

Hey guys, just a question, I've already got the 93 octane stage 1 tune. Are there any negative impacts to the car if i keep running it instead of switching to 91? Ceebs to pay another 50usd just for another ots map. Will switching to the 91 tune help gain more power?

Just add a few Litres of E85 on a full tank of 98 to bump up the octane. Our Australian fuel is not 93 AKI at all because our 98 RON fuels are designated a minimum standard of 85 MON which all the retailers basically abide to as a standard so its actually around 91-92AKI.

You wont gain any power with a 91 tune just way less timing corrections, smoother operation and less chance of knock.

[thiscarlife]

Originally Posted by SE7EN335

Just add a few Litres of E85 on a full tank of 98 to bump up the octane. Our Australian fuel is not 93 AKI at all because our 98 RON fuels are designated a minimum standard of 85 MON which all the retailers basically abide to as a standard so its actually around 91-92AKI.

You wont gain any power with a 91 tune just way less timing corrections, smoother operation and less chance of knock.

ahhh i see, how much e85 do you reckon is enough? never done this before

[SE7EN335]

Originally Posted by thiscarlife

ahhh i see, how much e85 do you reckon is enough? never done this before

5-7L on a full tank of 98 should make it around 93-94 AKI fuel.

[RevNev]

Originally Posted by robbo mcs

or 20% E85

Toluene has better knock resistance in 98 than E85, it's 124 Ron and 112 Mon. Ethanol's methylated spirits and the metho you buy at the shop is 98% Ethanol and 2% Methanol and you could use that added to 98 instead of E85. Xylene is another octane booster just under Toluene you can buy at Bunnings and it's not too hard to mix a brew if you're keen.

Hydrocarbons (Toluene/Xylene) won't lean the mixture out like alcohol and I'd make sure with an aftermarket tune that the mixture corrections function properly to accommodate for the oxygen content of alcohol additives.

[robbo mcs]

Originally Posted by RevNev

Toluene has better knock resistance in 98 than E85, it's 124 Ron and 112 Mon. Ethanol's methylated spirits and the metho you buy at the shop is 98% Ethanol and 2% Methanol and you could use that added to 98 instead of E85. Xylene is another octane booster just under Toluene you can buy at Bunnings and it's not too hard to mix a brew if you're keen.

Hydrocarbons (Toluene/Xylene) won't lean the mixture out like alcohol and I'd make sure with an aftermarket tune that the mixture corrections function properly to accommodate for the oxygen content of alcohol additives.

I have run both toluene and E85 blends in my racecars (not F80/82). Both do the job for knock resistance. E85 blends have the advantage that everything runs cooler as well. Also has the convenience that you can buy it at the pump, whereas toluene you have to buy in 20l cans.

I think most F80/82 users are going to find it easier to use E85 blends. Just fill it to 90% with pump 98 and then top up the last 7l with E85 from the pump. Easier than messing around with jerry cans or fuel jigglers trying to measure the toluene dilution.

If anyone is looking for toluene, when I was buying toluene (toluol) I bought it from these guys in Clyde (Sydney). http://www.greengoanna.com.au/

[RevNev]

Originally Posted by robbo mcs

Both do the job for knock resistance. E85 blends have the advantage that everything runs cooler as well.

Alcohol's fine providing the mapping accommodates the richness required to avoid pre-ignition. Whilst it's detonation resistant, alcohol has poor pre-ignition resistance with lean mixtures and high turbo boost pressure. Toluene has the advantage of being a hydrocarbon, it doesn't lean the mixture and maintains pre-ignition resistance.

It's just that flashing tunes unbeknown to us how they're configured, we need to make sure we're not running lean with addition of alcohol (E85).

[drgmt]

Originally Posted by RevNev

Alcohol's fine providing the mapping accommodates the richness required to avoid pre-ignition. Whilst it's detonation resistant, alcohol has poor pre-ignition resistance with lean mixtures and high turbo boost pressure. Toluene has the advantage of being a hydrocarbon, it doesn't lean the mixture and maintains pre-ignition resistance.

It's just that flashing tunes unbeknown to us how they're configured, we need to make sure we're not running lean with addition of alcohol (E85).

The other advantage of toluene is its carcinogenic.

[RevNev]

Originally Posted by drgmt

The other advantage of toluene is its carcinogenic.

Toluene and Xylene are primary octane boosters added to regular unleaded to result in 95 and 98 octane fuels. Hydrocarbons, MTBE and alcohol aside from tetraethyl lead are primarily the only octane boosting additives added to a base fuel. It's just that they don't add enough to result in a decent pump fuel to best accommodate performance engines that develop high cylinder pressures and remain detonation free.