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Most racing fuels can be used i standard engines, MON rating over 100 is common. But to get the extra horsepower some new maps will do the trick.
Like texan says, it doesn't mean that a higher octane fuel will burn slower. That is true, and it's only high octane not nitromethane we are talking about. If you use a fuel that burn slower, it will burn when it leave the combustion chamber.
The combustion in an engine (gas or diesel) are done very fast, it is done before the crankshaft have rotated 90 degrees. In engines that are using nitromethane (which burn slow and is hard to ignite) like top fuels the fuel is burning while leaving the cylinder. (but in these engines the exhaust valves also opens very early)
I know that there is a limit to what the ECU can control, let take the lambda sensor for an example, it can control around 10% of the fuel flow. If a turbocharged engine is used it can control much more. An example: The compression ratio is 9, maximum boost pressure is 1,4 bars. The total compression ratio can now go from under 9:1 up to 21.6:1.
If knock occurs, this is done:
1, More fuel to the engine
2, Ignition timing set a little later
3, decrease boost pressure
If no knocking occurs it will do the opposite.
In a racing engine the compression can be 6:1 and maximum boost pressure can be 4 bar, this mean that the total compression ratio can be 6:1-30:1. These engines use high octane, but they must also run well during no boost.
Engines today are built so the can run lambda 1 (with gasoline SAFR 14,7). This can only be done up to around 66% of the total rpm range and it can't be done during heavy load. This is because otherwise knocking will occur (fuel is a good cooling).
If unburnt fuel leave the cylinder it will damage the cat, but I have never heard anyone who had ruined it by using too high octane. This is mostly done because of misfires or if the engine gets to much fuel.
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