i have a 2005 mazda rx8 straight piped with magnaflow resonators, i was wondering because of the terrible gas mileage i get with my rotary engine will the mpg increase even a small amount? And if it will what is your recommended system?

 

The factory intake IS a cold air intake. Only Racing Beat or AEM will net any gain, and it is in the range of 1-2hp. No intake will help mileage, but plenty can hurt it with MAF flow disruption.

Mileage is all based on the health of:
- Engine compression
- MAF
- Front O2
- Ignition Coils
- Plug Wires
- Plugs

Assuming you don't have something odd like sludge for transmission fluid or dragging brakes.

A healthy 8 driven by a smooth driver can get ~22mpg with 100% highway, and ~17-18mpg city. Or better. If you aren't getting this, something on your car is failing or you spend a lot of time at full throttle.

 

I recommend that you re read the new and potential owners thread, it's all right there for you.
Good luck

 

Thank You!

 

I got a couple additional highway mpg with my 2008 40th anniversary edition RX8 with the Mazdaspeed/AEM CAI and BHR coils, wires ,new plugs and diligent maintenance and care.

 

You really won't see help in the MPG department with an intake. the AEM system is really the only one to run. The AEM adds a crazy engine note and you could see possible small gains. All the others suffer from heat soak or other issues to not net any gains.

AEM CAI System

 

The Racing beat with duct is much better than the AEM IMO. Looks better, sounds better, equal performance,no water issues, etc. And of course there are the JDM options (Autoexe, Amemiya, etc). But I hate the look of the AEM in the engine bay.

But the only intake worth a damn on an RX-8 is one that is connected to a compressor housing.

 

Another common problem for other brands is that they didn't properly R+D the MAF housing, or airflow through the housing. Bends too close before or after with nothing to straighten them, even if they got the inner diameter correct that would maintain the proper MAF calibration.

 

Hands down in our RX8 club the most bought intake is the AEM/Mazdaspeed (same part whether it says AEM or Mazdaspeed). I like my Mazdaspeed intakes I have had on both my 2008 Mazdaspeed3 GT (much more gain here on this turbocharged, direct injection engine) and my 2008 RX8 (slight gain on rotary engine).

Racing Beat once did a cold air intake test on NA rotaries and calculated that you could gain up to 1 hp for any additional 10 degrees F cooler intake air, depending on atmospheric conditions. I will try to find this info in a link so I don't get doubted here. LOL

 

Suggestion...

Run through the things in the congrats thread below, then a tune up. Then worry about mods.

The singles cheapest mod I found for MPG was to drop the front an inch. Gas savings paid for the springs in a few years. I got a little out of a tune as well, but that was for performance.