There's a few things I'd like to see done that would improve economy and all around performance. Unfortunately to do them would mean you no longer would have an RX-8. Maybe for another car though such as one based on the Kabura.

I'd like to see a car weigh no more than 2500 lbs max fully fueled. The lighter the better.

Better aerodynamics with careful underbody attention as has been mentioned. A lower drag coefficient helps at highways speeds.

I want Mazda to dump the damn 4.44:1 rear end ratio for something more real world. It's way too high. At the very least take it back to a 4.10:1 which is more than enough.

A smaller turbocharged rotary such as a 1 rotor turbo Renesis that puts out 200 hp. In a 2500 lb car it would be a lot of fun. This setup would also be more fuel efficient.

Those are a few things on my wish list. They should easily make for a car that car keep up if not beat an RX-8 in terms of acceleration and potentially handling depending on the car design. It should also yield a consistent 20+ mpg city and 30+ mpg highway. That's how I'd do it. Sorry guys. It won't happen on an RX-8. The first gen RX-7 idea is a good one though. I've got one. It's already under my target weight and already has a 4.10 rear end in it. Now if I could just afford a Renesis...

^ I'm wondering how much a 4.10 ratio would affect acceleration?

and as flexible as a rubber band.



But back on Topic... why would we even bother to look for better mileage???

what is wrong with the mileage of the RX-8? I typically get just a hair under 18 in mixed driving.

What is wrong with that??? That is the nearly the same or better than any other 200+ Hp modern sports car out there.

My 07 328i gets the same gas mileage with its 230hp motor. Yep, state of the art BMW motor gets the same mileage as the State of the art rotary motor in my 06 RX-8.

Heck, at least the mileage is better than my X5 which only gets 13 city and 20 highway.

I do have a suggestion that could work without spending any money .

I note with interest that some people get quite good freeway cruising MPG while most are 20 or below . Rather than blame the car , I would lay odds that those who get good mileage have have a slightly different driving style and here is why it makes such a big difference .
When you go from closed to open loop on the ECU the fuel consumption increases considerably .
The trick is to drive in such a way that you stay in closed loop as much as possible.

How do you do that ?
When you are at around 3700 rpm in 6th any slight acceleration will take you into open loop . The trick is smooth driving & no speeding up and slowing down at freeway cruising speeds .
For me this is impossible because this is boring but for many of you it would not take much of a change in driving habits to improve mileage .

trade it in for a Honduh ...

IMO, I think that the 6th gear is about as tall as it should be. With the low amounts of torque, I would think that making 6th any taller would bog the engine down terribly. It already has minimal pull in 6th.

I understand the thought process behind it, and as nice as it would be, I think that it's just not practical with a Renesis. I too thought it sat a little high in the RPMs when cruising at 70, but if hooked up with a taller gear, it would be about equivalent to mashing the gas in 6th going 45. Except you would be going 70...and likely would need the speed a little quicker.

Hydrogen Electrolysis
 

www.savefuel.ca
Too lengthy to explain here, but I have one of these units currently and I am getting twenty four miles to the gallon. And actually anyone can make one of these (high school science class, anyone? anyone?). All that you're basically doing is breaking water down into its elemental components (hydrogen/oxygen) and burning the hydrogen with the air and fuel instead of just burning the air and the fuel. All that I can say is..It works and pays for itself in about a year.
Otherwise, here are some options:
http://waterpoweredcar.com/hydrobooster2.html
http://www.thesietch.org/projects/Hy...aker/index.htm

hmmmmmmm

What type of snake was this oil extracted from?

AT 12 mpg, I'M LOOKING!

The 8 gets inconsistent mpg among its owners...some, like Raptor, gets horrendous mpgs, while others get 20+. Myself, I noticed that between city and highway, there isn't much change: 19-20 mpg. As for the driving style, I recently added some Chevron Fuel Injector cleaner with the V-power from Shell and am redlining it 2 times/day on a consistent basis and am noticing that the mpg isn't affected yet (150 miles at slightly under half-a-tank): carb-cleaning run @10K. I'm assuming when I fill up that my mpg is @17 or so. Not that much, considering I've been redlining it twice/day....wish my highway miles were better...but since I get such good in city mpg, I'm not complaining :) Just noting that mine is different from others out there...

I always figured that with the handbuilt Renesis engine, there must be some variables from engine to engine and that those that were getting better mileage must have a leaner air:fuel ratio helping them out (maybe differences in the MAF). But, when Racing Beat couldn't improve the mileage with a cracked computer, it really became a mystery to me how some people get such good mileage. I mean, if I drive on the freeway using cruise control, shouldn't I be able to match the high mileage some people get? There's something not connecting, but I don't know what it is.

Yep. Don't understand either..when I'm on the highway and set it to cruise, I don't seem to be getting as good as other 8 owners who says they had up to 25 mpg...I be lucky to break 21..but..like I said earlier, at least I'm getting somewhat decent mpg on both city & highway drives..when my mpg drops drastically..that is when I'll check out the MAF, air filter, plugs, etc...

I know it's not an RX-8 but my Honda has the same issues with cruise control. I can get better freeway mileage without it. This is due to hills and overpasses. Unless you are a completely flat road for miles on end, you should be able to beat the cruise control. When going up hills, even small ones like an overpass, the cruise control gives it more gas to hold the same speed. On larger hills (and I'm not talking about mountains) it may even floor it. I on the other hand may just let speed fall off a few mph or so. This actually saves alot of gas and your drive time doesn't suffer appreciably for it.

RG..does this applies to manual as well? I know this applies to automatic, since the computer isn't smart enough to know what gear to put itself in for the best performance (usually, it just floors it vs. gradual gas increase)...I'll have to drive it next time without cruise to see if it makes any difference..not that I'm complaining..but..it is weird..

I am a big cruise control user and I average only 19MPG on long road trips and there are not many big hills on the highways I frequent.

I've never owned an automatic.

Interesting take. I EXPECT my cruise to hold the speed I set it at. The 8 has been my best cruise control yet. Mainly because I set my cruise at the speed where I hope I won't get a ticket.......

When driving manually I don't let speed drop on purpose, however it probably does. On the same note, it climbs much higher when on manual as well....

I think a possible answer to better milage, at least on the freeways, would be some sort of rotor deactivation system (like Dodge has on their Hemi's).

We could program the ECU to run on one of the rotors while on the freeway just cruising and have both rotors kick in when we punch the gas or for normal driving (Manual override should be available of course :) ).

Either that or just have the motor alternate every other combustion cycle to deliver a charge. I like this idea best so it doesn't upset the balance of heat in the ngine too much or cause uneven wear.

Sounds simple enough........right? :Freak_ani


:dunno:

The only way to get it to alternate every other combustion cycle would call for a serious fuel delivery system redesign. It would have to include a direct chamber injection system due to the length of the runners and the number of intake ports.

Has anyone had any success running standalones on a Renesis yet?

hey, rotor deactivation. Great idea if it could be done.

I'm using four of these in my RX-8, and I've been running on the same gallon of gas for 2 years. Plus I use the surplus Hydrogen to heat my house. :lol:

I played with deactivating one rotor on my RX-7. I had to floor it to hold abour 45-50 mph in 1 rotor mode. It was quite lethargic and vibrated very badly. Admittedly it probably wasn't anywhere near an optimal setup but the first results weren't too promising. I'm sure it could have been improved upon in some way.

Well if Mazda is working on Direct Injection for the Renesis, then we just might have a solution. That way we can run both rotors and just alternate every other combustion cycle and not have the vibration associated with rotor deactivation that RotaryGod experienced with his experiment. :)

Your best bet to max mileage for minimum cost would be too:

1. Properly inflate tires
2. switch to synthetic tranny and diff fluid / synthetic motor oil
3. frequent clean MAF and filter
4. Racing Beat Intake system
5. Use 6th gear when ever possible

doing the above I average about 16.5mpg city and 24 / 25 HWY