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Originally Posted by SupraTT/Iceland
well what about 18 psi on pump gas? is that ok? the Gas that you can get here from pumps is 95 oct, 98 oct and Shell V-Power 99 octane
compared to America 99 octane here is like 95 octane in the Usa
I think you use PON(Pump Octane Number)
And we use RON(Research Octane Number)
So would it be ok to Use 93-94 octane(PON) at 18 psi ?
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The short answer to your question is no. For more detail, read on:
Ime, both RON and PON are useless figures. The only number that matters when you're taking about preventing detonation in a turbocharged engine is MON.
According to these links (and others):
http://www.btinternet.com/~madmole/R...RONMONPON.html
http://www.zeltex.com/eval.html
...the MON of what's referred to as 'premium' '93 octane pump gas' in the US is approximately 88. Ime on 88 MON 'premium' "pump" gas, you can boost to about 14psi without the Mkiv Supra Turbo's oem (unmodified) ecu detecting knock and retarding timing. 15psi is boarderline; at 16psi knock is clearly detectable and timing retard starts to occur. Every time you boost over 16psi (without some form of
effective octane suppliment, as listed in my previous post), you risk engine damage.