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If I am running my Beast at the track, and I'm still running stock engine management (unchipped), will the stock ECU detect that I am running higher octane fuel (100octane unleaded) and advance the timing for me, thus making a little more power? Or will running the higher octane have no effects at all without a Powerchip or tuning? :M5launch:
 

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I am editing my previous post. I don't think the engine will advance that much. I think it is mostly meant to adjust downward by sensing knock in lower octane gases. No knock, no upward adjustment over 93. There may be a slight improvement, but nothing to fully use 100 octane.
 

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Digi said:
I'd say that you will get more power than normal high octane fuel, because it will adjust somewhat. I wouldn't imagine it has enough adjustment range to make full use of 100 octane.
I'd agree with the above. I think these cars are really designed around 93-94 octane, but we're stuck with 91 in califonia. I think the car feels much better with a little 96 or 100 octane mixed in. I don't think you'd gain much over, say, 95 though.
mike
 

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I put 100 octane in my all motor M5 all the time. I would notice a smoother rev range and not as loud and crackely exhaust. It just sounded way smoother. At the drag strip, It made no difference in trap speed. Just felt and sounded smoother.

josh.
 

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phillym5 said:
I put 100 octane in my all motor M5 all the time. I would notice a smoother rev range and not as loud and crackely exhaust. It just sounded way smoother. At the drag strip, It made no difference in trap speed. Just felt and sounded smoother.

josh.
I've noticed the smoothness thing too. the engine did sound smoother, even quieter with higher octane fuel.

I suppose you could put that 100 octane to better use now... :M5launch:
Mike
 

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mottati said:
I'd agree with the above. I think these cars are really designed around 93-94 octane, but we're stuck with 91 in califonia. I think the car feels much better with a little 96 or 100 octane mixed in. I don't think you'd gain much over, say, 95 though.
mike
I also agree. When the car gets hot, a little extra octane will help. So 95 or maybe 96 is as much as you can use. Adding about a 1/3 tank of 100 should be enough (not including PhillyM5 and Abdullah!!).
Regards,
Jerry
 

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On a stock program, higher octane fuel should give you marginal extra HP! Apart from making your engine smoother and more efficient!

I would rather view it as " bringing back lost HP " rather than "gaining"!
 

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Higher Octane fuels generally have marginally lower calorific values... so if the ECU doesnt adjust for better fuels than 95 Octane then it's unlikeley to have any positive affect.

Dave
 

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mottati said:
I think the car feels much better with a little 96 or 100 octane mixed in.
Hello Mike,
mixing in high octane fuel usually has no effect. As long as there is lower octane fuel left in the mixture, it will ignite too early and cause the high octane part to ignite as well. So a mixture is basically not suitable to gain any timing advantages, because ignition timing is relatet to the lowest octane fraction of the mixture. You need to run nearly 100% high octane to have the effect, wich should be achieved after 2 or 3 complete fillings.
 

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hydreliox said:
...mixing in high octane fuel usually has no effect. As long as there is lower octane fuel left in the mixture, it will ignite too early and cause the high octane part to ignite as well. So a mixture is basically not suitable to gain any timing advantages, because ignition timing is relatet to the lowest octane fraction of the mixture. You need to run nearly 100% high octane to have the effect...
I'm sorry, but I couldn't disagree more. Toluene is an excellent blend stock that is widely used in both retail fuels and racing gasoline alike. Tetraethyl lead is another good example. I'm a chemist, not a petroleum engineer, but there's no question blending fuels is an effective way to change octane numbers.

Adding racing fuel (100 or 110 octane) to a partial tank of pump gas is common at the drag strip, and I can tell you first-hand that the effect on trap speeds are real. No dramatic, but real.
:flag:
 

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ELEVENS said:
I'm sorry, but I couldn't disagree more. Toluene is an excellent blend stock that is widely used in both retail fuels and racing gasoline alike. Tetraethyl lead is another good example. I'm a chemist, not a petroleum engineer, but there's no question blending fuels is an effective way to change octane numbers.

Adding racing fuel (100 or 110 octane) to a partial tank of pump gas is common at the drag strip, and I can tell you first-hand that the effect on trap speeds are real. No dramatic, but real.
:flag:
I agree. Toluene is very noticable in forced induction car. It raised the octane of all the fuel in the tank as it mixes. Toluene is cheaper than 100 octane (I believe it is closer to 110), but it must be handled VERY CAREFULLY.
Regards,
Jerry
 

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Hello!

I get the impression we are talking about two different things. I thought the post was about mixing normal gas of different octane numbers. Toluene sounds like a dedicated racing fuel :confused: , which is something I have no experience with.

In Europe major petrol companies offer three different grades of fuel: Normal (91 octane), Super (95 octane) and SuperPlus (98 - 100 octane). If you usually fill up with 95 and then mix in some of the 100 octane stuff, there will not be a noticeable effect. Even the petrol companies are stating this in their numerous brochures (eg, Shell / BP).
But I just recognized that octane-numbers in the US are not the same as in Europe, where the research octane number (ROZ) is used. This means: Your 100 octane are not the same as our 100 octane. So maybe this is why we come to different experiences and recommendations?

I have no cause to doubt the effectivity of your toluene blend and your first hand experience, I can only report my experiences with the fuel available here. :cheers:
 
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