Nopstnz8

iTrader: (6)

Learn how to drive and use this car how it's meant to be driven. Carry speed into corners and know your lines. That saves a lot of unnecessary braking and accelerating which increases your mpg and the grin on your face after =D

Grace_Excel

iTrader: (5)

This should be retitled: "How to get at least 20 mpg on RX8", that will eliminate all the attempts of going beyond that range since most average between 15 and 19 mpg, correct? Thus, stops all the nonsense posts and keep this thread dormant as it was just a few days ago.

zoomzoomlover

So let me restate my question. I've been getting 15 mpg average and I've read that decreasing mpg could be a sign of something wrong with the engine. I redline it everyday (how could you not in this beautiful beast?) I basically drive it like you all have said to drive it. BUT I'm never first off the line when messing around with my friends and racing their old beater cars. I don't have enough money for a turbo kit so I was thinking about getting a typhoon air intake for a little more torque and horsepower. I guess I was just hoping it would give me a little more mpg and that was my question to alllll you smart rx8 men, haha it was a yes or no question. With gas prices going up I just wanna know if itll help and if it doesn't I'm still getting the damn air intake anyways. Wasn't just getting it so I'd get better gas mileage, I'm not retarded.

RXeckless

iTrader: (5)

nycgps, it looks like you just got bitch slapped. You tell him girl!
I too get shitty MPG, it just part of owning a 8. My 20 year old FD gets better MPG than my 8. Both cars have about the same kilometers on their engines, go figure?

Just order new coils, plugs & wires, and hopefully I'll get back over 16 MPG but I doubt it.

wcs

iTrader: (2)

The problem you don't understand is it's not a simple question with a simple answer. If it was you wouldn't be here asking.
Lot's of people have been trying to get better fuel mileage out of the Rotary engine and it's just not easy.

Here's a quote from a great guy RIWWP in this thread https://www.rx8club.com/rx-8-discuss...thread-242295/
You should read the entire first 10 posts

Gas Mileage:
If you are considering, or have purchased, an 8, you will likely have one of 3 opinions on gas mileage:
1) I am buying a sports car, or won't be driving this regularly, so I really don't care about mileage
2) I care a bit about mileage, but I think what I get is fairly reasonable
3) WTF, I am getting terrible mileage, these car's suck! All RX-8's are gas guzzlers.

If you have the first or second opinion, then congratulations and join the club. If you have the 3rd, then keep it to yourself, we aren't interested in listening to it. Gas mileage has been discussed, killed, resurrected, killed again, reincarnated, burned alive at the stake, beheaded, cremated, and BURIED AT SEA. Please leave it there.

The reality is, a healthy RX-8 will get 17-18mpg city, 22+mpg highway. But 'healthy' means completely healthy: healthy coils, wires, plugs, O2 sensors, carbon free engine, good compression, healthy cat (or no cat), good transmission/diff fluid, no vacuum leaks, clean MAF, clean ESS. Let even one of these slide, and your mileage WILL drop, and it will drop fast. If you believe that RX-8s simply can not get this mileage because you have never seen it, then there is only 1 person to blame, and that is YOU. If you don't get this mileage, then there is something wrong with one of the above points. Or with your foot. Your right foot can make the mileage drop quite a bit as well. And I don't mean granny driving as the answer to good gas mileage. Smoothness is more important than speed. Smooth and fast is better mileage than unstable and slow.

People also tend to point at it being a 1.3L engine, and assume that a 240/238/232 hp rotary "2-stroke" engine is as efficient as a 1.3L 4-stroke piston engine (which is probably in the 70-90hp range). This simply is NOT the case.

So if you can't get this mileage, start poking around for what is wrong.

For reference, here is 8,330 miles of mileage data from my Sevenstock trip around the country in September 2010. The lowest tank was 13.99mpg (14mpg basically), and that was in non-stop tight curves on the Pacific Coast Highway where I was having fun blasting along. Note the 4 tanks over 23mpg, 11 tanks over 20.00mpg. Also note how the highway mileage drops as speeds go up. Once you cross the ~70mph range, the wind resistance does start stacking against you more and more. It's easily a several MPG drop going from a cruise of 70 to a cruise of 80+. And those were probably closer to 85-90. The 18mpg in northern NV wasn't really highway, but it was alot of really straight empty terrain, and speeds that I won't talk about publicly
Click this bar to view the full image.




Yes it can be a sign of failing ignition, poor compression, even a clogged catalytic (just to start with)

Hmmmm the redline a day thing is rather questionable.
There is some serious tech info by race teams that suggest otherwise. However without getting in to a holy war (like the oil discussion threads), you'll just have to decide on your own.

You should delete (edit) this from your post.
Any mention of street racing and you'll be banned.
It's against the forum rulz

It won't do either, actually you may loose HP and Torque.
This intake is a hot air intake.

The RX8 stock comes with a cold air intake, and it is quite good.

IMO no it won't and if it does it would be by such a small amount it wouldn't be impossible to rule out that other factors that may have impacted your fuel mileage.


This intake may cause other issues like poor idle, hesitation and stalling.
Save your money.
This is a very expensive car to own and operate there is no magic bullet.

Other threads you should be aware of:
https://www.rx8club.com/rx-8-discuss...thread-242295/
https://www.rx8club.com/rx-8-discuss...llowed-208221/
https://www.rx8club.com/rx-8-discuss...rx-8-a-233937/



Happy now?
Bye-bye

04Green

iTrader: (1)

Hm,

Someone who shares our views, saved to buy the car, is new to our group, actually searches searches to make sure they post in the right area, posts in the correct area, asks for help, and gets motives, intelligence and decisions attacked.

Must be RX8Club.com...

zoomzoomlover, the data from WCS and RX is good. You can decide on the rest. With an 04, the stuff in the First $100 thread below is a good place to start. It worked well on mine.

And, welcome.

zoomzoomlover

Thanks to those who gave me actual suggestions! I am most definitely asking questions about my car on another site next time!

MikeTyson8MyKids

iTrader: (1)

This is the best one for this car.

Lots of good info on here, a lot of it disorganized and threads ending in death spirals...lol. Just check out the sticky threads, and ignore the trolls.

RIWWP

iTrader: (2)

Moderator note:
I've deleted many of the recent posts in this thread rather than closing it. The thread has value for new owners that are trying to figure out why they aren't getting acceptable mileage. If someone posts a question relating to this very specific topic with mileage numbers that indicate something is wrong, bashing them for asking isn't kosher in my book. Yes, there is reading that can be done by the poster, but that does NOT excuse the responses I've deleted.

If you look down on other members so severely and are incapable of restraining yourself then maybe you should reconsider your membership in a community of human beings.




Zoomzoomlover,

Just like any community out there, we have all personalities, all types. This really is the best source of information about the RX-8. Unfortunately you sometimes have to wade through individuals that are incapable of providing opinions, suggestions, or facts with any level of civility. We try to crop such behavior when we see it, and encourage people to bring such to our attention. We can't change who people are though, and some people just don't like other humans.

Beodude

iTrader: (3)

From my experience, I've gotten a very consistent 18-19 mpg, no matter how I drive. I took out the cat, got a reman engine under warranty, BHR ignition, clean MAF... Pretty much everything I could think of. No matter what happens, it never seems to change. Within 1 mpg per tank, even on 100% highway. I got AccessPORT now, so we'll see how that does.

But do I care? Nope!

ASH8

SO many other variables which owners usually fail to think about when comparing MPG.

Taking we give it as a given that the RX-8 or your RX-8's Engine is in 'Good' running condition.
Ignition is fine, a good grade of fuel is used, pre-mix even.

Then something which is always overlooked when comparing MPG to other RX-8's is your cars Power To Weight, put simply a driver weighing in @ 78 KG's is going to get better mileage than a driver who weighs 110 KG.

Or take a look at what you are hauling around (more weight), like tools (in Trunk), what is on the back or passenger seat or floor?.

Tyre pressures and tyre condition?

And last the weather, wet roads will always create extra drag, like having another 40 KG in the Trunk, or hight humidity, re intake temps or air temps.

Using your Air Conditioner?

So many variables, is it any wonder some don't get the same MPG results as others.

RIWWP

iTrader: (2)

Nope, not really


Tire diameter can matter too. Not so much the actual mileage you get, although it will still vary slightly. But say if you have tires that are 5% smaller overall diameter, your odometer will rack up 5% more miles between fillups, inflating the amount. On the flip side, larger diameters will reflect a drop in perceived mileage

sd1611

I am more concerned with a considerable change in mpg, assuming normal driving habits. That can indicate something is not right. Other than that I just drive it and not worry too much about MPG.

paimon.soror

iTrader: (15)

fyi when driving a standard transmission, the left foot is more important than the right foot when trying to save some gas ...

i.e. not leveraging off of engine braking is the most common cause of $hitty gas mileage amongst 'newb' standard transmission drivers.

HiFlite999

iTrader: (2)

Goods and Bads for better mpgs:

Fresh coils and plugs = good
Coils wired to wrong plugs = (very) bad
Tires inflated to 35 psi or higher = good
Performance summer tires = bad
Tire life ratings over 300 = good
Wider than stock tires = bad
High rpm = bad
High speeds = bad
Steady throttle/speed = good
Gentle acceleration, skip shifting when possible = good
Gentle braking (in gear) = good
Higher final gearing = good
Stock "bannana" spoiler = good
Big wing or other downforce mods = bad
Side skirts = (theoretically) good
High altitude = good
Cobb "Economy" tune = good
Lowering "enrichment" mode temps to come off colder = good
Cold weather = bad
Higher viscosity oil = bad
Too cold water or oil temps = bad
Mod for higher oil pressure = bad
Highest outside temp one can run without A/C or open windows = good
Open sunroof = bad
Lowered suspension = good
Coasting in neutral (manual transmission) = bad
Correct stock alignment = good
Modified exhaust = mixed

Gas engines putting out a low percentage of their rated power have sigificant efficiency losses due to sucking against a nearly-closed throttle plate. Thin, hot air requires the throttle to be more open for a given modest output (though max output will be reduced). In that sense, CAI and bypassing the throttle-body heat is bad for mpg's.

RIWWP

iTrader: (2)

Good list.
Open windows = bad


Hmm, I wonder...

I know the 8's intake is already complicated enough, and a simplification is the direction Mazda is going, but I wonder about "2 intake path" setup. The theory that is churning in my brain is that in closed loop under a certain airflow cap, the engine is pulling air through a separate intake track that is smaller diameter, lower peak flow, but essentially "wide open" for that track. Climb above the threshhold and it either flips back to the main intake or opens up the main intake as well.

I know that this is largely what is being targeted by the various intake valving we have, but none of that really affects the throttle body itself, which as you state is still nearly closed. Mazda tuned the intake for power, but I could see the same method adopted for minimum pumping losses at cruise airflow levels, but taking it the whole way to the throttle body.

Especially with a drive by wire throttle, I could easily see programming to hold the primary throttle closed and only open a smaller secondary throttle for the smaller intake line up to a demand point, and then open the main as needed.

I'm sure someone out there has tried such a thing.

thomthoms3

iTrader: (1)

The point of having an RX-8 is not to get good gas mileage. This is kinda what you signed up for when you purchased it. Rotary engines need gasoline, much more than piston engines would. If you are willing to drive under 3k rpm just to attempt to save gas, then buy an MX-5.

RIWWP

iTrader: (2)

Yes, it is foolish to hope you will get 30+mpg out of your RX-8. However that doesn't mean that only getting 9-15 with 100% highway is normal.

Gas mileage is a VERY good indicator of the condition of the drivetrain. It should be within an expected range, and if not there is something wrong that needs to be fixed. Everything mechanical that can cause your mileage to drop will lead to cascading failures of other components if not addressed.

There is still value in paying attention to the mileage you are getting.


(and I did actually buy an MX-5 too. Two of them even ... one with a turbo attached )

thomthoms3

iTrader: (1)

Right, if someone is getting extremely bad gas mileage then it definitely is important to look into. I've just read one too many posts about someone who is unhappy about their 17 mpg and trash the RX-8 because of it. I know that's not the case here, but expecting 20-22 city is just unrealistic. I drive about 200 miles per fill up (roughly 15mpg) and that's with the factors of redline a day, lots of hill driving, and what not included. Even on the highway which I rarely take, I get about 18 mpg (but that's probably because I'm always well above 4k rpm when I'm in sixth).

How do you like your MX-5(s)? I heard those things are monsters with turbos (then again, what isn't?). I almost got one instead of my 8, but wanted it because insurance was way cheaper and I wanted to experience the rotary engine (and it was a good choice of course!)
-T

RIWWP

iTrader: (2)

I'll send a PM to answer that to avoid derailing the thread.

DinSum

iTrader: (7)

Very nice! I agree with all of it except coasting in neutral. For sure coasting in neutral helps mileage, I can coast a full kilometer when doing 100km/h and I find coasting at the right times helps mileage quite a lot, I dont see how its bad for mileage :/

HiFlite999

iTrader: (2)

Simple, with our (MT) cars, the fuel is completely shut off when the gas pedal is released (which also enhances engine braking). With the clutch in, fuel is supplied to keep the engine running. To avoid the engine braking, just be in a relatively high gear.

paimon.soror

iTrader: (15)

Coasting neutral uses far more gas than using engine braking ... watch afr's for confirmation.... hence what i meant when i said the left foot is more important than the right foot for MT drivers.

DinSum

iTrader: (7)

Im going to have to disagree

when you leave the car in gear yes it uses no gas, but it will slow your car down three times as fast as being in Neutral so the only time its more benifitial to leave it in gear is if you are doing city driving and you have to stop a lot without much warning. So try this, go 60mph then let go of the gas and see how far you get before it stops, you wont get nearly as far as being in neutral especially if the road has a slight decline.but the disadvantage of being in neutral is your engine uses a little bit of fuel to idle, but it uses very little fuel when idling compaired to actually driving so after much testing and compairing with torque mpg readings its better to pop in neutral when going fast and you see the red light far ahead of you, then pop it in 6th gear right before getting to the red light to save a little more fuel.

I personally do both, but I know the right times where each has its advantage

So yeah being in neutral and leaving in gear both have their advantages, but saying that coasting in neutral is "bad" for mpg i think is off

get torque or a scanguage to get mpg readings and prove it for yourself, ive spent the last two months compairing

paimon.soror

iTrader: (15)

Why else would you coast? Are you telling me that you coast on the highway in neutral? Are you stupid?

Btw, go to skip barber and take a lesson ... you will be surprised how many times you actually make use of (or lack there of) the neutral gear.