What fuel in a Forester STI in various states of tune?

What fuel in a Forester STI in various states of tune?

Author
Discussion

Ryvita

Original Poster:

716 posts

216 months

Monday 10th March 2014
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Simple question really:

Will a standard imported Forester STI (fresh off the boat) run off standard petrol?
Same question for a Litchfield one?

If not, is it something that would usually be deal with via a remap, or are there some that just have to be run religiously on an Optimax diet?

rb5er

11,657 posts

178 months

Monday 10th March 2014
quotequote all
Standard Japanese fuel is 99ron. You want to get as close to that as possible so best to use super/v-power etc.

Uk standard cheap stuff is 95ron and not a great idea to use on these engines.

Edited by rb5er on Monday 10th March 17:12

arfur

3,887 posts

220 months

Monday 10th March 2014
quotequote all
Mine only ran on Tesco 99 or Shell VPower for 160k miles

MikeyLCR

501 posts

187 months

Monday 10th March 2014
quotequote all
arfur said:
Mine only ran on Tesco 99 or Shell VPower for 160k miles
+1 for the 87k that mines done.

bonesX

902 posts

186 months

Thursday 13th March 2014
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Japanese petrol is 100 RON

If fresh off the boat, I would fully decat, fit a high capacity fuel pump and get it remapped. Should see ~330BHP and improved low end grunt - nice smile

Fleetwood

28 posts

148 months

Friday 14th March 2014
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When I got my FSTI I took it to Surrey Rolling Road with the standard map and dynoed it on VPOWER and it had a clean bill of health (no pulled timing or hesitation on WOT).
When I pull the ECU stored values I am getting IAM=1 (full advance timing applied to ignition) and little or no timing pulled with fine learning knock correction so...
I think you will be OK on VPOWER without a remap.

The odd time that I have had to run 97RON Texaco or other brand the car felt fine and although you might get slightly more fine learning knock correction IAM still =1

US Subarus have a good and bad fuel map and the ECU adjusts the ratio between them depending upon the quality. The JDM forester STI only has a single ignition map but still gradually applies the advance map on top which adds timing depending upon the fuel quality so it can handle poor fuel, you just don't want to run it on cr*p all the time.

Hope this helps!

Fleetwood

28 posts

148 months

Friday 14th March 2014
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If you do the things suggested by BonesX you will get more power obviously, but if you run on VPOWER you will be fine for now and can decide later what you want to do about a remap or new performance parts.