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Octane vs Altitude

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Old 27 August 2003, 08:31 AM   #1
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Is it still relative for me to run 100 RON while living at an altitude of between 4000 and 5000 feet above sea level.
Does the turbo compensate for this surely 1 bar manifold pressure at sea level and 1 bar at 4000 feet above is the same thing.
The only thing i can see that may be different is the density so would 95 RON on a JDM ECU ( Mine's ) be ok or am I barking up the wrong tree here.
A friend of mine here has a Nissan Pulsar 4x4 pushing 300 and when he fills racing fuel of approx 103RON he gets knock do you think that there may be a happy medium and what would that be??

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Old 29 August 2003, 05:57 PM   #2
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If the pressure is the same, only the temperature will affect the density of the charge. Maybe the air temperature at 4,000 feet is low enough that the density will be higher than for the same boost at sea level. In that case you would get more power for the same boost pressure. It is a moot point whether the higher power at higher density will cause more chance of detonation than the effect of a higher charge temperature with a lower power output at the same boost levels.

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alt, altitude, density, elevation, octane, rating, sea, verses, versus

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