4) I didn't search at all.

Cumulative Gas Mileage (Gas MPG) Thread
https://www.rx8club.com/showthread.p...t=MPG+Increase

 

the two biggest factors you want to consider:
1. you probably wont be able to change the fuel burning efficiency too much; a cobb accessport will help you tweak for better mpg a small bit. higher compression ratios = more efficient burn but that has to be balanced with octane, chamber geometry, etc and is not cheap to change lol.

2. weight. lower car weight = better mpg across the board. however this is also not cheap or practical in most cases. there are some things you can do.

the RX8 is not a gas miser, it's a sports car. its for zoom zoom. :D

you can look for tips on ecomodder.com but really your best bet is to get a civic or corolla for miser commuting, and enjoy your RX8 on weekends

 

fuel pressure, forget it. bigger injectors? nonsense. if you remap the control unit to run leaner, you'll destroy the cat with the increased egt's. weight is a rather minor issue when it comes to cruising mpg. reduce the rotor mass?? take an intro physics course.

 

i use fuelly.com to record my gas fill ups and miles ive driven and it calculates my mpg. for the past month ive been showing 17.6-18.0 mpg. if your getting 20 your not doing to bad.

 

What about gearing? 6th seems useless as a cruising gear on the highway. If you could get down to, say, 2500 RPM @ 120 Kph would that make a difference?

 

good luck with that .

Like Hiflite says - to get better mileage you could lose the cat and run a leaner mix via the AP .
Getting the diff out of an AT may help a little as well - but you would lose in other areas .

 

 

Trying thinking. At at steady 70 mph down the interstate, the 8 gets at most 25 mpg, which is totally crappy for a small, 3,000 lb car. The engine is producing power delivered to the rear wheels which is being used to overcome drag. Weight and rotational moments of inertia don't enter into direct consideration. A freakin 4,200 lb Sienna minivan gets 25 mpg under the same condition.

What gives better atomization, a 1/2" garden hose (high flow, low pressure) or a 1/2" garden hose with a nozzle (low flow, high pressure)? With 2 seconds thought, your proposal makes no sense. With some reading, you'd realize that the manufacturers for both gas and diesel engines are trending in exactly the opposite direction - smaller injectors running at much much higher pressures, like 100 psi going to 10000 psi.

There are plenty of 100 mpg carburetors and little magnet thingies attached to fuel lines that also promise "better vaporization".

You need a cat because it's, at minimum, legally required. If you run cat-less (and enjoy stinky exhaust) or go the route of getting a better cat which can stand higher EGT's, then redo the fuel maps to get rid of the extreme rich conditions, mpg's will improve, but I can't find anyone on the list to present numbers. It will never be as good as a piston engine equivalent.

Running a taller 6th gear (MT) would likely help some on highway, as the engine is turning ~3,700 @ 70 mph. Whether it's worth the money to modify, or causes even worse problems with carbon buildup is questionable.

One could go to a taller rear end ratio - and suffer even slower acceleration. One could also go to narrow-profile, low resistance tires and wheels - and cornering will suffer.

I rather suspect that if Mazda could deliver a 25/29 mpg RX-8 through some clever little change, they would have already done so. Or perhaps you are vastly more clever than they are, though from your comments and general inability to master the form of a complete sentence in English, I rather doubt it.

 

stop. there was already another current mpg thread. move this over there.