I was told if you run 91 octane on a jdm itr with the p73 ecu that it pulls the timing back so the motor will not detonate since its running a more aggresive tune. My question is how much power am I losing while running 91 instead of running 100+91? Also would it be better to get it tuned with a chipped p28 to run 91? Any input would be greatly appreciated. sorry if this was brought up before I am still a noob =(

 

Octanes are rated differently in other parts of the world. For example, our premium, using the octane rating formula in North America - (RON+MON)/2 - is considered 91-93 octane, so that is what's specified. The exact same fuel, using the octane rating formula in most countries, is considered 96-98 octane using the RON formula, so that's the number required over there. When they say that 91 octane isn't good enough, they are referring to regular gasoline that would be considered 87 or less octane over here. You should be fine using our premium fuel.

 

Thank you very much for your response.

 

JDM P73 uses a knock sensor. This means if the sensor hears knock, it will retard the timing no matter what fuel you use. Weather or not the sensor hears knock will depend on how you wire up your knock sensor. The OEM manual specifically shows that the knock sensor uses sheilded wire grounded in a very specific way. Without sheilded wire, it is possible that electrical interference could trigger the knock sensor. If you do not set it up the same as OEM, I would not expect it function as OEM...

If you don't want to bother with knock sensors and worry about knock retard, then use a custom P28 (or upgraded P06).