I still get 17.5 mpg so I'm happy

My rx8 gets 17.5-18 so far all city, so *meh*

 

I'd like to see the proof of this "theory". The comon sense aproach here would be that your car at 40 is either bogging in 5th or riding comfortably in 4th, which means the engine is combusting more fuel per mile due to rpm conversion through the tranny or it's not close to it's peak performance. I would wager (knows little about characteristics of flame fronts and other neato things in the combustion process) that our peak torque (about 3500 rpms) in 5th will be the best possible gas milleage. This is backed up by everything said here. It could be possible, and i'll go out on a limb here, that you do know a severe amount of detail about engines and that you just forgot to mention the gear issue, probably the most important part and that what ur saying is refering to peak engine performance.

 

Welp, if you're happy, that's all that matters.
I've gotten *28* MPG driving almost all freeway.
That's a 400+ mile distance between gas fill-up's on a 16.6 gallon Zenki gas tank.
If you're happy with your 18mpg city, does this make me on cloud 9 with my 28mpg?


-Ted

 

Sounds about right to me!

As near as I can tell, the closer I can run to 3500 RPM, the better the fuel economy. The trips when I'm cruising slower due to police presence (quota time), I get worse economy.

However, the 3500 RPM point may actually be an artificial limit due to the stock ECU. The S4 NA ECU, at least, goes out of closed loop mode at right around 3500 RPM. It also will end up dropping out of closed loop mode on most hills at that speed, just due to the manifold pressure requirements to maintain speed.

The real test of the engine would be to get a nicely tuned standalone & do the mileage calculation. From talking to people with tuned standalones (usually running in open loop mode at cruise, just tuned with a wideband, and usually a bit lean of stoich), fuel economy doesn't begin to drop significantly until somewhere over 100mph. The engine efficiency apparently rises more or less proportional to air drag until that point.

... I'd love to find a place to test this. Anyone know somewhere in the US I can run 100+ for miles on end without getting pulled over?

The other interesting question is, "What kind of fuel economy do other cars get at 85-100mph?" I know I can do a bit more for economy (get the injectors cleaned, get a standalone), but I'm still pulling 23-25mpg cruising at 80-85. What does a typical Honda or Toyota get at those speeds? Suddenly a '7 doesn't look *quite* as bad...

-=Russ=-

 

My 89 CARBURATED toyota corolla SR5 pulls 44MPG at those speeds (80-90MPH) on the highway. :P

 

At 100 MPH, my Insight will do 55-60 MPG all day. At 85 MPH, around 70 MPG. Slow down to 65 MPH, and you're getting 85-95 MPG.

 

if I had an Insite I would spray paint the windows black and wear a bag over my head.

 

I'll keep that in mind the next time I drive 1000 miles on 10 gallons of gas...

 

and use the money you save to buy more **** for the RX-7

and i guess if you believe in equilibrium or whatever, the Insight balances out the inefficiency and emissions of the 7, hehe...

 

put a turbo on that Insight.............who needs 60+mpg jk

 

56mpg on my 1.6L non-turbo diesel jetta (1984) with a minor fuel leak - SUCKA - LOL
BTW - that was calculated at 130kms an hour on a trip to daytona beach for spring break last year
But bear in mind that that power plant only cranks out 52 bhp and 61ftlbs at the flywheel, so you damn well better get some good mileage!!

 

I drive 35 miles a day onFC3C n/a, 4 city, 31 hwy. Im reverse commute, so freeway is 75-100, top down on way home, paying 2.69 gallon, cant stand 3100 rpms, so about 15-18, but I dont work Fridays anymore, should improve there, so------who cares!!! I didnt buy my FC to drive like my mother. If I keep it where it is at, Im happy. I guess I could put in regular gas, yeah right. If I worried about mpg, I would have bought a tricycle.
Peace. RUF RUF RUF

 

u cant put a s-afc on a first gen to lean it out so how can u lean it out. would that be with that black dial in the engine compartment