You bought the wrong car, bro.

 

Why is it that maximizing handling and engine performance is OK but working on fuel consumption makes you a *****?
Vasily never said he wanted Prius level mpg, he just wants to know how to make his car as efficient as possible, which seems reasonable to me.

 

No one said he was a *****, thats how rumors get started

 

Well u are what u eat so I never take that as an insult. Maybe OP is the same? Just do the maintenance stuff and be easy on the gas. But not to the point where u don't enjoy the car Lol.

 

I think a lot of people take that approach becasue they can then internally justify the fact their car is poorly tuned, way too rich and quite possibly a hacked up mess. They just say "It's a sports car...I don't care about mileage!" without realizing that not only is that money out the tailpipe, but horsepowers as well.

Reminds me years ago of when I bought my Insight and the car was made fun of for many of the things that RX-7 people love. Unique, light weight, distinctive drivetrain, etc. Odd how these characterists are a good thing when applied to a performance car, but strangely a bad thing when used for efficiency.

With a standalone, assuming no radical porting (bridgeports need not apply), there's no reason at all why factory fuel economy numbers can't be beaten. Case in point, this past summer I tuned a single turbo FD w/street port that gets above 30 highway MPG, city MPGs in the mid 20s, makes about 350HP and passes emissions.

And then people forget how 12A 1st gens were EPA rated at just above 30 highway MPG.

 

Have a professional tuner install and tune a standalone EMS, preferably one with SFI and individual injector trim. This will cost around $1,500 to $10,000, but as stated by Aaron Cake the car will get about 30 mpg highway if it is in good condition. However, if your goal is to save money, then this may not be the best option.

If the goal is to save money, then I have found that the best way to do this is to plan well. Use the telephone rather than driving around town shopping, and a GPS (Googlemaps if you don't have a GPS) helps make trips more efficient. Carpooling is good too, as is walking.

Keep in mind that super unleaded fuel is only for resistance to detonation, so if you don't need it then use regular unleaded fuel. Top Tier gas has extra detergent that will keep your fuel system cleaner without needing to use that overpriced additive crap that the auto parts store tries to sell you.
Top Tier Gasoline

The EPA estimated gas mileage for an 1989 RX-7 TII was 16mpg city and 24mpg highway. The current revised numbers are 15mpg city and 22mpg highway.

Things that cause bad gas mileage:
- Tires not inflated correctly or tires wider than stock.
- Steering not aligned or other suspension problems.
- Carrying a lot of weight.
- Engine worn.
- O2 sensor bad.
- Leaky fuel injectors.
- Using ethanol-enriched fuel or "winter" fuel.
- Driving with the AC on or the windows down.
- Rapid acceleration.
- Driving over 55mph.
- Excessive idling (for example, getting stuck in traffic).

If the engine does not go past 3800rpm on a somewhat regular basis, the secondary injectors will clog up with sludge, and then on that one day that you do need to accelerate your engine will blow up. I have seen it happen, and it isn't pretty. DO NOT DO THIS! You can drive the car past 3800rpm with gentle acceleration if you like. The other option is to regularly clean the secondary fuel injectors and air bleeds so they don't clog up from lack of use.

At the bottom of the tachometer there is an amber "^ Shift Up" light that comes on as you are driving. Yes, the annoying one that you have been ignoring all this time. That is the ECU telling you when to upshift for best fuel economy. It works best under slow acceleration, and it is for upshifting so it will show false indications when downshifting.

 

the 85 brochure says 23/17 for the 12A, 23/16 for the GSL-SE

 

to me, running one of these engines in economy mode poses other issues. sticking intake sleeves and carboned up rotors.


sure, economy on a lambo V12 could be improved upon but it won't like it. yes, i just compared a V12 to a 13B.... haha.

the main problem i see is money dumped into the car to usually not affect mileage to a large benefit. problems usually arise outside of tune up components and the system is a closed loop non learning/adjusting management system so it relies on everything mounted to the engine to be working perfectly to get the ideal mileage or chuck the standalone at it, tune it and be out $1500 to save a few hundred a year in additional gas.

if you get 14+ city and 20+ highway you probably shouldn't expect much more. the 30 mpg figures are extreme examples, something i have never seen on a rotary regardless that people claim it to be possible.

 

my TII with haltech e6k regulary got 28 mpg on interstate trips. keeping headlights down and a/c off helped. im sure if it was non-turbo and higher diff gearing, it would break 30mpg

another interesting factor is keeping secondary throttle plates closed. i noticed that would get you another 2-3 mpg, it keeps air flow velocity up, since its only using your primary ports

 

I was referring to the earlier thermal reactor 1st gens. The later 12As had to run richer for the cats. I believe the earlier engines were the "lean burn" 12As.

Funny, it's almost like Mazda knew what they were doing when they put all these "unnecessary" parts in the engine bay, eh?

Late opening the secondary throttles or keeping the vacuum secondaries is a trick I'm going to employ on my Cosmo to maximize economy and low end.

 

Mazda called the mid 70's engines "lean burn" but the SAE paper from 1981 explains how they leaned the engine out further so that they could use a cat.

of course it also looks like the EPA changed the way they rate MPG in the middle somewhere, the 84 brochure says the 12A will get 29 highway!

oh BTW it is interesting that a 20% improvement in fuel economy is only like 1mpg

 

without boost the car is slow, with boost fuel economy stinks

no boost- dull and boring

Having an optimal engine is awesome, but saving $5 a fill up and not enjoying the car makes no sense

leave the hypermilling to the prius guys

 

Stance it with herrafrush 0 offset 11" wide varstonnens on 195 tires (just a little camber and fender work, no biggie), get a 4" fart cannon out the back and a dryer hose/OBX filter for the intake. Now underlight it, chop the springs, and put some Illest stickers on the paintjob.

35mpg easy. Plastidip get you another 5mpg or 10rwhp, your choice.

 

the thermal reactor on the early engines required richer mixtures because the reaction required unburnt fuel versus what the cat relied upon which was less fuel.

honestly, mixtures do not need to be very rich for a catalyst to survive. too rich and the cat fails prematurely from the opposite end of the spectrum, contrary to the belief that the cat needs rich mixtures to live.

 

yes, the rotary catalyst SAE paper is kind of funny, they had to lower HC's at the engine before they COULD put a cat on it, so they had to improve a few things (spark plug placement, port air injection, apex seals) before they could run a cat.

 

you mean HAD to put a cat on it.

stupid regulations, the EGR system was a total joke and an unecessary failure point for absolutely no benefit until it failed, then the result was even more emissions. rotaries have a built in EGR inside the engine after all, but of course the EPA wouldn't listen.

external loads/creature comforts also reduce economy, if you want a few more mpg strip all the unecessary items off. even without the cat/smog pump you can squeeze out another 3-5mpg by increasing timing a few degrees and leaning out the mixture further.

 

lol, yes, that little snippet i posted form the paper almost literally says that. "to meet the stringent 1981 emissions requirements"

 

the OP will no doubt achieve much better fuel economy now

 

since i saw no note of what he was actually getting, of course there is no way to know how much it could be improved by lacking maintenance or an ECU going nuts from faulty inputs resulting in horrible economy.

who knows, he may have thrown a walbro in it like so many other n/a fools thinking that an upgrade is an upgrade.

 

I'm finding that the rotary engine likes to be driven a very particular way. City is bad. New plugs, oil, single piston calipers, and small rims help. Drive it extremely smooth, and never slow down. Use the cars dynamic to maintain speed and keep the gas pedal steady. Between shifts, take a long time, and let the car do the work, not the engine. Pretend it's a propeller plane, and try to keep the rpms fairly constant, like youre flying. Don't on off the throttle like a piston car. Drive 70 on the freeway and draft. When starting from a stop use first gear to get you into a good rpm for a moderate climb in second, abut 20mph. The fc's weighty, so be patient and enjoy the grand touring aspect in street driving. The more you enjoy the grand touring aspect, the better. I can't stress maintaining high speed during low speed maneuvering. What you lose off the line you'll make up on dive bombing 25mph zones and on decel. It's a strange game and driving style, driving a rotary. Leave your piston driving habits at the door. Glide.

 

Could you expand on the this? Is it safew to asume that the extra degress in timing would be in the entire vac map? And what are the cons of doing this?

 

EGTs can get too high and you start melting exhaust parts

 

I would assume thats under extreme conditions, to the point where the engine is bucking as its starves for fuel.

 

egt probably peaks before the engine will buck, bucking probably means the thing is too lean to run, so it'll be colder

i you do a little reading on the EGT subject, most of it relates to airplanes, and this is fine except the airplane engine basically sees a constant rpm the whole time, while a car is not. for example, take off is like 2500rpm, and cruise is 2400rpm

 

the EGTs would probably go up slightly with everything maximized but not enough to do any real damage(mainly due to the performance increase).

the cruising timing maps are somewhat retarded to keep emissions down in the low load areas, especially at curb idle(which is also to help smooth out engine operation).