Timing and high octane fuel
 

FC TII streetported rebuilt motor
1990 JDM
HKS GT3037
550/1680 (with resistors)
AP Engineering PFC

I have the datalogit and although I am using a map sourced from BDC I was wondering just how much different my map should be using 97 RON and higher fuel. We are blessed in the UK to get 99RON which has been proven to have just that octane level, now you chaps in the US use 93RON and lower so the question is how will this affect my map timings if I use a map for 93RON using 97RON and higher.

The maps will come in handy as we can use regular 95RON fuel which is cheaper but then when you have an RX7 that only does 4K miles a year- then when it does hit the roads its at full throttle so I would much rather have a map for high octane fuel.

In the US we use a different rating system for gasoline. Your 98RON is equal to our 93OCT fuel. 95RON = 91OCT. BDC's map is more than likely based off of a 93OCT (though you may double check with Brian) and if you are using 98/99RON fuel it should be very close.

I would keep it the same but that's my opinion. I tend towards erring on the side of conservatism.

B

the closest thing to US 93 octane (93 Anti Knock Index, or RON + MON / 2 ) is 98 RON.