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So a question followed by a possible warning...

United now have there "race" e85 at the pump (107 octane).

Question being what happens if your tuned on regular e85, and use the 107 e85?

The warning, IF the above can have adverse effects.

Filling up regular e85 from united, normally pink, this time was green.

United website and facebook page state that green dye is an indicator of the 107 e85.

Again, this was from the regular e85 pump.

I usually check every couple of weeks for ethanol content (usually 90%) and thought i would share. United claim that keep a constant 85% ethanol, and do not change consistency seasonally.

Maybe its nothing, but now im curious....

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If you had a wideband sensor you could monitor afrs to see if its running differently, though I suspect there wouldn't be much difference so long as the ethanol content is much the same as before.

We just filled up the race car with some of the new blend and the green colour was the first thing I noticed also. The bowser didn't have the new stickering or signage to indicate it was the new race blend either. Car ran fine at the track this morning, though my engine is a NA LS1 which isn't as critical with afrs as a turbo'd car.

Do an ethanol content test on the new stuff and see what it comes up at maybe??

The ethanol content is the same, the difference is the 15% petrol used is now premium 98 octane petrol over the lower grade they used to use. Raising the octane rating from 105 to 107.

Theoretically even more knock resistance which is a bit redundant on E85 :P

The ethanol content is the same, the difference is the 15% petrol used is now premium 98 octane petrol over the lower grade they used to use. Raising the octane rating from 105 to 107.

Theoretically even more knock resistance which is a bit redundant on E85 :P

more knock resistance is ALWAYS good as long as it doesn't cost you power.

Beyond that it also means you can tune it harder. Also a good thing.

  • Like 1

Yeh i thought as much.

Higher octane= more knock resistance (theoretically and if the ethanol content is of the same consistency, which it is).

Glad to hear we share the same thought process though.

Ive messaged united just to see if they can shed some light as to whats going on.

Ill run the green stuff and keep my ears out and get back to everyone with results if any.

Cheers for the response guys.

Yeh i thought as much.

Higher octane= more knock resistance (theoretically and if the ethanol content is of the same consistency, which it is).

Glad to hear we share the same thought process though.

Ive messaged united just to see if they can shed some light as to whats going on.

Ill run the green stuff and keep my ears out and get back to everyone with results if any.

Cheers for the response guys.

Woftam.

Ethanol blends don't gain much knock resistance with increases in eth % above 40% anyway. You pretty much have to stop adding timing before the engine will knock for other reasons anyway. Ergo, adding 98 instead of the normal sheep dip won't mean you can tune it harder at all.

  • Like 3

Woftam.

Ethanol blends don't gain much knock resistance with increases in eth % above 40% anyway. You pretty much have to stop adding timing before the engine will knock for other reasons anyway. Ergo, adding 98 instead of the normal sheep dip won't mean you can tune it harder at all.

Ah, interesting. Cheers for clarifying that.

Loving the sheep dip call :P

So what is it that racers are utilising when using the very high octane race fuels? IS that when they have mad compression ratios? or is this the whole 'highly oxygenated' thing mentioned above?

mad compression ratios and heaps of boost will get some use out of the extra octane. But im talking like 2 Bar of boost which is more drag/VL territory these days. 2 bar in a skyline would be mental on the track

Edited by Blackkers
  • Like 1

Even at 2 bar the extra octane won't make much difference, mine peaks at 30psi

Like already stated it would need to be mega boost and compression to notice the difference

Something more the. 9.5 compression is where it would start to really be needed, 99% of rbs are no where near that

Something else to think about is what takes an engine closer to detonation ie heat and pressure .

If you choose to run an engine lean for any reason a few extra points of octane may make the difference between detonating or not . Granted if you ran it really lean it would lose power but detonation is generally the biggest baddest wolf .

When I was doing 50/50 E85/7Eleven 98 I screwed it up once with too much E85 and while it carried on a bit it still ran and showed some out there Lamda numbers .

From what I read leaded Avgas was designed to be run in aircraft cruising with lean mixtures for economy - range . The slow burning high octane characteristics suit lean running without detonation though they have heat temperature measurement so they don't seize valves in guides and fall out of the sky .

Just on E85 I get it from near Potts Hill but occasionally from Ingleburn , I noticed the latter stuff looked different but I was topping up because the price cycle lunge is due any day . I think the petrol octane number becomes more important as the ethanol content drops so 98E30 should work better than 91E30 .

No doubt the fuel suppliers will do what earns them the best returns so 98E85 is probably dearer than 91E85 . If the ethanol content floats around 90% then anything that's flammable with no water would probably do .

We really need an octane/ethanol blend standard to sort out the mess because with alcohol percentage on one hand and petrol octane on the other it's BS .

A .

mad compression ratios and heaps of boost will get some use out of the extra octane. But im talking like 2 Bar of boost which is more drag/VL territory these days. 2 bar in a skyline would be mental on the track

more like 40-50psi +..1000Hp+,

most people setups don't even need half of the e85s octane atm

cheers

darren

Edited by jet_r31

The problem with flex tuning is having no way to measure the petrol parts octane . To be totally "safe" you'd have to start off with E85 and increase the 91 ULP content until it was all 91 .

You could imagine what would happen if you flex tuned using only 98PULP blends , some goose gasses it up with straight 91 or 95 and rattle rattle bang - DOH .

A .

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