Jump to content
Ultimate Subaru Message Board

EJ18 exhaust redcommendations for best gas mileage?


Recommended Posts

I dropped an EJ18 into my Legacy LSi.

 

Does anyone have a clue as to what exhaust mod's might beef up the gas mileage for highway type driving?

 

Should I be looking at the headers all the way back or just the muffler?

I don't mind a little louder but my goal has nothing to do with sound either.

 

I'll probably go with a Dynomax muffler since that sounded and performed well on the XT6.

Link to comment
Share on other sites

The stock EJ22 exhaust is probably pretty decent in terms of flow for the EJ18 engine. I don't really see you getting a huge gain in gas mileage by doing anything to the exhaust. If you want to try something, I'd start with the muffler since it's the cheapest. Anything else IMO the benefit doesn't outweigh the cost....if you're just looking for gas savings.

Link to comment
Share on other sites

if you're just looking for gas savings.
that was kind of the goal with this car...see how well it can do on the highway. a friend needs an exhaust (midpipe/converter) for his legacy so i could donate mine while he gets a free exhaust if there was a good option for mine.

 

i tried poking around at NASIOC but didn't find much. found enough gas mileage threads but nothing substantial.

 

for the XT6 replacing the stock muffler is about the best you can do for highway gas mileage. high flow converters, headers (though that is only with a stock exhaust), straight pipes, removing the converters, etc make no noticeable difference in mileage. i was hoping someone might have similar experience with EJ stuff.

 

thanks for the notes.

Link to comment
Share on other sites

what you'll generally find is that the engine uses the same amount of fuel (FI, of course) no matter what the exhaust is doing unless it's REALLY stopped up. You might get better POWER but no real increase in fuel economy. In the old days, we used to "tune" exhausts to a resonance frequency to attain max power, but "today" it doesn't seem to matter much

Link to comment
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
 Share

×
×
  • Create New...