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Al Eckstadt
Al Eckstadt
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And just a silly note
A friend tried avgas in his B50
It dissolved the nylon fuel strainer in the banjo.

Another member used Flash lube in his bikes.
Because he had a bad ticker he always tipped out whatever fuel was left after a run & bought new for the next ride.
He put the unused fuel in his truck.
The flashlube prevented it from knocking so the knock sensor never triggered and kept on advancing the spark.
His ECU simply advanced the spark till the engine knocked then backed off a little


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did that cause a problem?

most engines are knock limited


i'm old enough to remember when patriotism meant not trying to overthrow the government.
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knuckle head
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knuckle head
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Many new US market high performance engines ,auto and bike, are designed to make advertised power on 91 octane fuel. If you use lower octane the knock sensors ,if detonation is sensed, will pull back timing and may also adjust fuel trims usually reducing power...I don't know what goes on with higher octane fuel...As you know.on many engines increasing timing beyond what's required can reduce power. It may take the ECU a few tries to adjust so the engine could knock for a second or two...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
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DOPE
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i dont know. surely the typical tuning map doesnt set total advance bazed only on knock. do any systems uze exhaust gas temperature rather than a knock sensor?

advance would have tobe limited somehow based o. n other parameters


i'm old enough to remember when patriotism meant not trying to overthrow the government.
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Quote
The flashlube prevented it from knocking so the knock sensor never triggered and kept on advancing the spark.
His ECU simply advanced the spark till the engine knocked then backed off a little

ECU's have a base map which has the full advance figures for using best available fuel, the knock sensor is used to find the knock point and the ECU reduces the advance until the knocking stops, it then stores it in modified ignition table and works to this table. With my Turbo SAAB 9000 if you got a fresh tank full of 5 star fuel then you pulled fuse no 5 for 30 secs so the ECU lost its modified table and reverted to the factory table and enjoyed higher performance as the fresh fuel would not knock until a higher advance.

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knuckle head
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Some vehicles have timing and fuel trims on the conservative side to limit warranty claims...Let's say an engine has 32 degrees total advance for rated power on 91 octane US gas....if you use 100 octane unleaded race fuel it will advance it a bit. Or not depending on what the maximum advance is where the engine starts to lose power.. this is determined primarily by combustion chamber design.....And on a stock engine, dyno and road testing by engineers...


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Aug 2001
Posts: 776
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Well, after over 30 elaborate responses, we have an answer to a simply question.
Do our BSA engine require an additive?
The answer is no! 91 octane works fine.

The wizards have spoken.

2 members like this: Gary E, gavin eisler
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