That's actually true and does apply here as well. You will produce more hp for same gas consumed after most mods. The problem is your boost will climb faster, have a high overall level meaning more fuel injected. For the same power levels you will get better fuel economy after the mods. How do you dial the hp back though. Lower the boost.

 

thank you all.

until i save up for the bonez cat, what should i do, not take it past 5psi and not pask 300rpm? the stock cat was blown and needed to be replaces because it has 90000miles on it. this is the whole reasoning behind me going all out on this :-/

again, thank you for helping me with all this.

 

FWIW, I can get 27mpg on the highway while still having a bit of fun on on-ramps and WOT passing occasionally. I usually cruise around 75-80 mph. Someday I want to try and hit 30mpg, I'll need an interstate with no hills though lol.

Relevant mods: Full 3" exhaust, intake, SMIC, RX7.com ECU

Gas mileage under spirited driving is... uhhh... not so great. But the fun is worth the gas money.

 

well if you can get steve kan to tune your car he can net you 20mpg on a highway tune with 93 yeilding around 380hp....dont remember the setup my friend gabe an i saw him do this on his fd....we were ecstatic!

 

With a full exhaust and a non-ported wastegate, you should be.

Dave

 

I get around 27-29 mpg combination of highway and street driving. Non-Sequential and a few new parts and pieces help that. I was amazed how it has changed from when I had first got the car. The gas mileage was around 15-20 mpg. It is amazing what a rebuild, fuel filter, plugs and wires, and turning can do for you.

 

Certainly I wouldn't expect to see much improvment on the stock ECU.

Can anyone attest that they saw an improvement between:
- Well-tuned PFC, mild or no mods
- Well-tuned PFC, moderate or heavy mods

I'm really curious about that - whether the additional mods made a measurable change in highway fuel economy.

Dave

 

I'm only seeing 18+ MPG in combined street/freeway driving. But that's beacuase I like boosting everywhere I can.

 

LOL! MPG on an FD solely depend on your driving behavior. If you like to boost and drive like a mad man on the road, you'll get 8 MPG. If you like to drive like a granny, you'll get 25 MPG.
I've done all in between and thats what I got.

If you truely want to save gas, go buy a hybrid as a daily. It will balance it out in term of gas and environment

 

11 mpg city with no boosting, ******* the **** out of it only drops me to around 9.5 mpg (traffic limited). Around 24 mpg highway normal driving.

 

Keeping the plugs and O2 sensor fresh will help mileage around town. The stock ecu only looks at the O2 sensor under idle and light engine loads. You won't notice any real drivability difference if it needs replacing but you'll notice the mileage dropping.

 

I wonder what gives if you run your motor real lean at highway speeds/rpm with low throttle? Doesn't the egt go way high? If so, what happens in the long run??