Suparslinc

I've been around the RX-7 community long enough to know that these cars don't get 30 mpg. However, I see several members getting 20-24 on a tank, and am at my wits end on this.
I have consistently been calculating ~16 mpg. Here are the obvious things I have replaced and considered:
-all filters, including air, oil, and fuel are clean.
-compression is good. I had it tested about 2 years ago and only one chamber registered on the low side, and it was still well within specs.
-carburator is recently rebuilt. I have larger primaries and mech. secondaries, and a slightly larger accellerator pump shot.. I'd say I run on the primaries 95% of the time. Not enough hard driving to warrant this kind of mileage.
-ignition timing seems good. The car starts on the first or second crank when its warm. When the engine is cold it will stall out at first, then fire and sometimes blow a little smoke. I recently restored the vacuum timing advance hoping for some improvement but got none.
-good NGK plugs and NGK wires.
-RB cat replacement pipe, so a clogged convertor is not the problem.
-Blocked off shutter valve.
-Removed A/C and PS. No rear carpet or spare tire.

If you can help me save a couple bucks I'd be grateful. I drive around town alot, short trips. But no matter how long or hard I drive I still get the same results!

RotorMotorDriver

iTrader: (1)

I get 14 MPG from my car in my sig .

~T.J.

Suparslinc

I'm frustated dammit!

RotorMotorDriver

iTrader: (1)

I'm sorry dammit!

~T.J.

bliffle

I share your pain. I bought the 83 new in 82 and I am the only driver for 115k miles. It still runs like new. BUT my gas mileage has dropped from 22 to 16. The only thing non-stock is the shutter valve, which went out 2 yrs ao, so I blocked the hole in the air box to promote smooth running. I do not know how this could effect mileage or if my poor mileage started just then. My ignition replaceables are new, and I have no reason to suspect fuel feed, as it still starts like the day I bought it: I seldom need to even touch the choke.

B

snake eyes<l><l>

well, you also need to think about how you drive, if you run it to redline once a day, its not goin to be that high, ditto if you spend most of the time stop and go. mine got 16-18 to the gallon mosltly cause i would drive it around town, but when i jumped on the highway (and actually moved on i-10 hehe) i got about 20 mpg

my .02

<l><l>

Suparslinc

I've been playing with the carb a little; tomorrow I'm going to do a search on the correct settings for the mixture/ air bleed screws and try and set it to stock. But I think I did this once before and the engine went lean; I'm curious, how much does your idle speed and mixture affect gas mileage?

MosesX605

Losing the shutter valve will decrease gas mileage methinks. The 79-80 models didn't have the shutter valve, and they were rated less than the later models that had it equipped. The idle circuit shouldn't effect gas mileage a ton, but it may make some impact. I would say that your difficulties lie in the larger accell pump shot and the mech secondaries.

NanaimoRx-7

I think Mech Secondaires increased my gas mileage. Less bogging on hills and comfortable cruising on the highway without the vaccum secondaries tryng to come on at every tap of the gas. I also get 20-24 on combined city/highway/race tanks. Less in winter and less if it's always short trips around town.

RotorMotorDriver

iTrader: (1)

I think the stock mixture setting for the Nikki was like 3 or 3.5 turns out from a soft seat or something like that...

~T.J.

racermike

"""I have larger primaries and mech. secondaries, and a slightly larger accellerator pump shot.. ,,,,,,,I drive around town alot, ,,,,,,1984 GSL
modded carb,,,,"""

I'm betting you're getting "about" expected milage.........Go on a LONG, highway, drive a couple of times @ 55mph (without passing everything on the road) and see what you get. Or maybe put an uncooked egg under your right foot ..........

branca

iTrader: (1)

you might consider replacing the rest of your exhaust.

the gas mileage on my 83 (96k mi) went from 16 to 21mpg (and even better on all highway driving) after the entire exhaust system was replaced with a RB collected header, high flow cat and RB muffler

wwilliam54

put a 302 in it

^__^

Mr. ImportGuy

My racecar gets like 10mpg lol, sports cars arn't suposed to get good mpg are they??

vipernicus42

iTrader: (4)

And these rotaries don't like "short drives"... The car runs best when warmed up and driven for longer periods, especially on highway driving. "Around Town" driving is not what this car is meant for, and is probably one of the many causes of your low gas milage. More highway driving, or more driving when it's warm will hopefully help you out.

*hopes shutter valve doesn't drop gas milage*... I just blocked mine off!

Jon

gamble302

my car is a freak of nature i think. streetport 12a with rb holley kit and rb exhaust and i get 24 mpg on a regular basis, 17 or so if i romp on it for the entire tank. got 27 mpg on the way to new orleans once :O

851stgen12a

I get about 7MPG at the racetrack,
12mpg in the city,
About 16-18 average for just regular driving (to and from work and Kung Fu)
And about 28MPG on a long highway cruise, with speeds vairying between 70 and 90 the entire way. Average MPH is about 80.

I have noticed about a 1 or 2 MPG increase since I started running 6oz of 2cycle oil, and 2oz MMO.


Micah

ZoomZoom

iTrader: (2)

Wow that sux guys. I get 19-20 mpg and I have over 400HP at the wheels!

851stgen12a

The torbo actually helps the motor run more efficeantly, so at low boost levels you will probobly get better milage.

WackyRotary

Yeah, rotary and mpg are a love hate relationship.

Stock 12a with 55mph driving ONLY will yield near 30mpg.

Stock 12a driven our furum's "norm" would be more like 17mpg.

mildport 12a for me gets only ~10%less mpg overall

12a Bridgeport driven "normally" for me at least yields 14mpg, but I managed 19mpg once on a "highway only" drive.

12a Bridgeport driven on track yields me ~7mpg. Same with the turbo on it on the track.

I have found, SO FAR, that a stockport+turbo driven "our" normal is about 17mpg, not bad huh?
Mildport with the same setup gets about the same too. SO the turbo myth is going to get you much worse mpg is only myth unless you drive it VERY hard all the time.

MRGSL-SE

if you really wanna save on gas... go fuel injected... and get like the motec ecu or a HKS fuel/air controller and a 120cc fuel injectors or smaller if you can find one... a really huge AIR FLOW METER and run the damn thing lean... not too lean to cause it to detonate, but a 16.5:1 ratio as to 14.7:1 stoic ratio... and put a high flow cat to give some restrictions.... you can't drive it hard... its my theory on saving gas to the extreme...

racermike

Feel better Suparslinc ?? And we haven't even touched on tire size yet! Here is one tip though, put Amsoil 75w90 in the tranny and diff.....