hello eveyone. I am getting my 2.5 wrx a full de cat exhaust and remap done in a couple of weeks, and am wondering whether to fill it up with a high octane fuel can anyone tell me if its worth it and if it will run ok if i then switch back to normal 95 octane fuel.

 

Always use high octane fuel fella! V-power or Tesco super, the car will perform better at all times and you will notice the difference!

 

wot no v power dont wait for the remap go for it now look after your engine.......... give it the best...

 

As above, also once it's been mapped for v-power don't use anything except v-power or Tesco 99 (different to Tesco super). If you really get stuck then Esso Super and Total are the next best (avoid BP Ultimate at all costs) but you will need to add octane booster to be safe or drive like granny!

 

has the newer wrx ecu an option to run duel maps?could be an option to run both fuels.if not and you want to use 95ron then have it mapped on it.

 

AFAIK only the new age STI's (later models) have the option for 2 maps, wrx's dont.

Tony

 

Jim, the ECU will 'see' whatever fuel is in use, so will get mapped to that fuel's octane rating (resistance threshold to detonation). So it follows that the highest RON you put in, will be the best for potential peak bhp/torque capability and therefore performance. So 99 RON V-Power would be the best. But unless the ECU is capable of retarding ignition and lowering boost, then do not use lower octane fuel such as 95 RON after it's been mapped on the higher stuff.

What ECU do you have? The ESL daughterboad can adapt to different octanes, but the A'PEXi PFC cannot, for example.

I have a PFC and had it mapped on Esso 97... BUT use 99 RON, so as to give my motor a bit of protective headroom should the conditions for possible detonation arise.

 

^^^^^^ don't know why more people don't do that, map on 97 ron and run it on 99, for the sake of losing a few horses you will have a safer running engine.

- if you want to run it on 95, then get it mapped to that and you'll be fine! - but obviously the car wont be producing as much power as if it was mapped on vpower etc.

 

That all depends on how far you tune the ignition within the fuel threshold window, i you leave plenty of headroom on 99 or vpower (97 with additives) then a lower octane fuel within reason would be acceptable, with sensible use of course. Mapping to a lower octane fuel and then using higher octane would change your flamefront and ultimately increase egt temps. Its more about thermal management than power management.

@

 

you really think the octane between 97 and 99 will make that much difference???