Octane?

[fishbone]

You would need bigger injectors, a bigger fuel pump and especially a tune to be able to run E85

[cortman]

No I think he is talking about 85 octane gas, not E85(which is a dumb idea in any car).

 

In the western US you can buy 85 octane gas, for some reason.

If the 2.5i has a knock sensor you can dump it in. The only drawback will be lost power, and possibly worse fuel economy. The knock sensor will tell the ecm to back off the timing until it stops pinging.

[ripemeat]

putting a lower octane gas than what the car was designed to run at is a retarded(no pun intended) idea. The ECU will pull timing like a mother, power will decrease, efficiency will decrease. Ignition advance multiplier will drop when it detects widespread knock (usually the case when crappy gas or lower oct gas is put into any 2002+ subaru). This means the total ignition timing is decreased, meaning less power, less efficiency.

 

You do not want knock, it is harmful to the pistons. put 87 or better in. subarus DO run more efficiently with higher than 87 in, depending on how bad the knock correction looks while on 87 in your particular car. Subaru factory tunes in general suck, so a 2.5i is likely to still have some knock even on 87. therefore putting higher octane in should eliminate and/or reduce that knock, meaning, more timing is able to be utilized (to the limits of the knock correction advance timing table). What I'm saying is, it's very likely that running 89+ octane will maximize the efficiency of the engine, reduce knock, and very slightly increase power/response.

[GEE-OTTO]

I was recently in Denver and saw 85 OCT for the first time ( i live in VA) I typically run 93 OCT (tuned for it) now I know if I ever go across country to re-flash to the 87 map !

[awdG35killer]

Denver has 85 octane. I've been running 85 in my 2010 civic auto for 36k miles and still average 30mpg 90% city. I've run 87 for the first few tanks and for the same average. Manual says it requires 87 Oct.

 

Nothing retarded about that. I understand using the recommended in turbo or bigger engine cars but there hasn't been loss in mpg or knock here .

 

I was just wondering if anyone has tried 85 in the na legacy and what results were.

[fishbone]

Elevation makes the car less prone to knock. 85 in Colorado is fine.

[ripemeat]

Denver has 85 octane. I've been running 85 in my 2010 civic auto for 36k miles and still average 30mpg 90% city. I've run 87 for the first few tanks and for the same average. Manual says it requires 87 Oct.

 

Nothing retarded about that. I understand using the recommended in turbo or bigger engine cars but there hasn't been loss in mpg or knock here .

 

I was just wondering if anyone has tried 85 in the na legacy and what results were.

 

You have no idea if your civic is/has knocked. And don't say because you haven't heard it ping. In general, forced induction + knock = bad, but knock even in an N/A is still bad, adding boost to the equation makes the damage a lot worse. Results may not be noticeable on paper, but the engine will like you a lot more if you just used the recommended god damn octane.

[awdG35killer]

You have no idea if your civic is/has knocked. And don't say because you haven't heard it ping. In general, forced induction + knock = bad, but knock even in an N/A is still bad, adding boost to the equation makes the damage a lot worse. Results may not be noticeable on paper, but the engine will like you a lot more if you just used the recommended god damn octane.

 

Understood and I'm all for using the recommended. Just that I know people that have lived here for 15+ years and still use 85 oct in all their vehicles with no issues. But all vehicles are different so was just checking.