Being a Mazda tech for the past 6months, I've learned a few things bout the rotary engine that a good majority of the members on the forums don't think about or just don't want to comprehend. These motors are designed for abuse (high rpm, high compression). What kills these motors are driving them like they are piston engines and heat. Keeping the the oil cool is a major factor. The apex seals although they have spring tension the inertia from the rotors spinning is also what seals and keeps the compression up. Stay up on the oil changes and at least once a month get a fuel system service to keep the carbon build up down. I get bout 230-250 miles on one tank of gas not cuz I baby the car I drive it the way it was designed to be with out making an *** of myself on the streets.

 

What fuel system service do you suggest? And any thoughts about BG 44K?

 

BG 44K works well mainly for cleaning lines and combustion chambers, we use optimizer (its like seafoam) this is injected in the intake manifold or throttle body while the vehicle is running at operating temp it takes 2 people one keeping the rpms at about 2500-3000k and the other spraying in the motor the white foam expands in the intake breaking up oil and carbon build up also cleaning out the combustion chamber, it's safe for cats and O2S and also can revive low compression.

 

well i was getting 14mpg, now im getting 21 mpg. All i did was remove my vfad. I guess it wasn't working. It also adds a ram air type effect.

 

Doesnt removing the vfad result in less hp at higher rpms? I was reading about in another thread saying the vfad helps the 6port retain hp when accessed at higher rpms...idk how much of this is true for I am just learning about the rx8...so if you have less hp does that mean better mpg?

 

not really. You see if my vfad was working improperly like i was suspecting it was then at higher speed i was running richer cuz i wasn't getting enough air. From all i read the vfad was for noise suppressing at low rpm. I noticed that im about 500 - 800 rpm lower at 70mph now as a result. and if it is lowering the hp at higher rpm;s than its so little i don't notice. It did seem to help a lil on my low end. Before since it was malfunctioning i had a hard time getting over 6500 rpm, and when i did i would get miac and a rough idle like it was choking out, which it was, basically it was flooded. Besides mine not working correctly, most of your aftermarket intakes require the removal of this device anyways to replace with theirs that has no vfad. Or do like most people who do free mods and remove the fvad, remove the flaps inside the air box, and add a high flow filter and you have a free version of the $300+ air intake kits.

 

Hmmm ill take a look at that because I came across a diy on removing it

 

Newbie - 2011 Sport, manual. I drive 90% freeway, and can't seem to hit 21 mpg. I keep car in 6th, 60 - 71 mph. Several times in the last few weeks, encountered a flow of traffic in the 76 - 81 mph range, and followed along (once following a CHP at 81 for miles). Oddly enough, the regular fill ups seemed to require less fuel - is this possible?

 

ya.. its possible if your gauge is wrong lol. most people don't hit over 21. check some basic things to be sure you couldn't do better. your usual plugs/wire/coils/oilchange/air filter/tire pressure/lead foot take offs and passing lol. also try premixing people who do that seem to have more reliable engines.

 

How are you calculating (estimating?) your fuel consumption?
What do you mean by "regular fillups require less fuel" ?
What is the ambient air temperature during these drives (the fuel consumption is quite sensitive to temp)?

I doubt a year old car needs plugs, wires, coils, MAF, etc. Is the car modified in any way?

 

In this case. no calculations. I drive the same set pattern every day, and fill up after the same segments to work and back - 225 miles. Normally takes over 11 gallons, after driving faster, it only took like 10.7 to refill. Thinking maybe engine changes >3800 RPM increase efficiency? temps are roughly the same - I travel at the same time every day.

 

My mpg increased (as well as power) around the 40K mark. I'm not sure if it was the mileage or maybe an ecu flash. This was back around 2004/2005 when I was at 40K.
I have 93K on my original engine and I average around 17mpg mixed driving. I still get around 20/21mpg on long 80mph highway drives. I redline it a least once a day, if not more ; )

 

I've had my 8 now for about 6 weeks. 2007 with Mazdaspeed CAI, 59K miles. I average about 20 MPG, which based on what I have read is pretty good. One thing I did notice is that I've varied the Octane just to see what the results were and I'm getting about the same on reg or premium.

 

somewhere I read that extra ports open at 3850 RPM. (about 72 mph) - wondering if efficiency increases above 72 mph resulting in better mpg

 

Hard to say on the M/T models (it is 3750 rpm, by the way), but I would guess that air resistence would override any efficiency increase. Also, don't the secondary injectors come online at about the same RPM?

This certainly is not the case with the much higher geared A/T models. To cruise at 3750 rpm in 6th gear, the car would be going over 112 mph. Not very economical, according to my scangauge !

 

Great article with excellent idea! I appreciate your post. Thanks so much and let keep on sharing your stuffs.

 

Bought a '04 GT 6 speed with 42k back in Jan. of this year. I was getting 20 mpg highway (75mph average) and 13 mpg city. None of the previous owners did any maintenance from what I could gather, and that means the coils had 42k miles too. Plus, I was having misfiring issues from 7000 to 9000 rpm. After new coils, wires, and plugs, no more misfiring problems, and I am averaging 17 mpg combined with 21 pure highway and 14 when I drive her like I stole it. Also, highly recommend the K&N Typhoon short ram. It sounds amazing with zero mpg lost from what I can tell.

 

I get 15l/100km in 170km/h.... but at high way

 

I got about 24 mpg when I bought the car with a mostly highway trip, with some spirited acceleration in the mix.

Mostly city driving, with no respect to idling, temps, etc. and I consistently get between 17-19 mpg, depending on the % of aggressive vs mild driving it gets during that time.

Once I can get her running (starter not responding), and do the tune-up stuff I wish to do, I plan to 'hypermile' a tank city, and a tank highway ... and give some results.

I've owned a 05 civic hybrid (avg 58 mpg), an 07 prius (avg 52 mpg), and a 12 cr-z (avg 42 mpg) ... so plenty of experience with getting excellent fuel efficiency, including getting >40 mpg out of a 99 accord sedan that was grossly overloaded, and >30 mpg out of my FC 7s highway low 20s city.

gas mileage relies on 1) vehicle in good repair 2) conditions driven 3) driver ability to drive slow and smooth. 3 is the reason people can't meet sticker, if you drive it like you stole it, let it idle, don't conserve momentum, drive at excessive speeds (even 70 mph there is a **** ton of air resistance), drive up and down hills/mountains, drive in extreme heat/cold/weather, drive short trips, drive in congested traffic, stop and go traffic, and never perform proper maintenance ... you should never expect to see anything close to the EPA numbers, in ANY vehicle. If you drive with conservation in mind, plan your routes, have perfect conditions, you can slaughter the EPA figures with minimal effort. The EPA there is for COMPARISON to other cars only, not to tell you what you should get ... and if you don't, blame the manufacturer. The opposite is true. Blame your conditions and yourself (for not having discipline). This is why you see people bitch and whine about hybrids getting 30 mpg ... while in the same vehicle, I've pulled >90 mpg on a highway trip (nearly 1000 miles on one <11 gal tank). The same car will get 30 mpg in a snow winter with idling to warm up the (inside) car, or less if you don't drive far ... or if you constantly fight mountains, you should still see a lot less efficiency, because you can never fully recover the uphill cost from the downhill run.

Remember, because of gearing, wind resistance ... the optimum speeds for most cars will be between 40-60 mph, anything above 60 the force to cut the air become a detriment to your efficiency.

In my future experiment, I'd like to see 21-24 mpg city, 30-33+ mpg highway (3-500 miles/tank). I think that is a good start, and the only people that could milk more out of it take efficiency extremely seriously, while for me it is just a part time game I've picked up over the years to see how disciplined I can be, and what a car can really do at BOTH ends of the spectrum.


p.s. I wish the U.S. would switch to metric ... it'd be nice to have the whole world on the same measuring system, metric being more accurate and easier to work with (base 10 vs fractions and uneven numbers of measurement 5280 ft = mile vs 1000 m = 1 km).

 

Wow you guys actually have it pretty damn good! I AVG 14-18mpg at best, No highways where i live in the uk just winding B roads. When i went to Japfest i covered 160 miles and it cost me about £80 all motorway driving.

Looking online your fuel is about $3.50 per gallon which is about 3.8 litres (we buy metric...gay) Fuel atm near me is £1.36 per litre, That makes it about £5.20 per gallon which is about $8!! Thats more than double what you pay! How is that bloody fair lol Wish i could pay £2.20 per gallon :'( Working more out our fuel prices in 2002 were slightly worse than yours are now. The only good side is Tesco do 99 Octane for £1.40 per litre (The 8 lurves it)

I really cant afford my car but i love it sooo much i'd sell my wife/sister/mum/nan to be able to run it 365 days a year would love some fuel delivered in barrels

Sorry its a little off topic,just thought i'd share my $0.02

 

My 04 has a newly installed, reman engine (at 65k miles). This time I am premixing with Idemitsu and noticed an additional 50 miles on a tank. Is that normal anybody?

 

Got a reman in my car 2 weeks ago. Gas mileage sky rocketed. i used to do about 230 miles per tank.

My first tank of gas got me 274 miles, I thought something was wrong. I filled up 12.6 gallons to the top at costco. 2nd tank got me 272 miles to the light.

Now im on pace for about the same mileage again on my 3rd tank. 100 miles and still above halfway.

I didnt know this car could be fuel efficient!

 

Figured I'd post this here as I have no clue whats going on, recently did a clutch and flywheel instal with the ACT street disk and lighter flywheel. Since I got the car back my MPG has decreased significantly. Any thoughts I was at around 18mpg, now im getting around 13mpg. Everything runs fine no signs of a bad instal car drives perfectly. Any thoughts. History on car is 2004 M/T 6port with 28K miles. besides clutch full engine back exhaust other than that stock car. Any thoughts on my suffering mpg i kinda miss getting 200 miles out of a tank

 

djfa:
Yeah, people that don't believe it usually have something wrong with their car.

r24:
Coils, plugs, wires, vacuum leak, both O2 sensors, compression, MAF, air filter, cat, etc...

You had to remove the cat for the install, and it's possible that it got damaged (not likely, but possibly depending on how it was handled). Also the transmission could have crimped or pinched the wiring harness that runs to the O2 sensors.

Or you just have a failure unrelated to the clutch/flywheel replacement.

 

I already have a P0420 code for my midepipe that has been present for months I don't think thats the problem since it just started happening. Out of laziness for now ill sum it up to more spirited driving since i really haven't put many miles on and ive been driving her pretty hard since she goes in the garage for the winter soon. so we will see if i calm down. I just wanted to make sure that a lightweight flywheel shouldn't result in an mpg decrease, i would assume i should expect a small increase in mpg due to the decreased weight. Time will tell.