First, to even have a reasonable estimate of fuel mileage, you must track it, not guess. Write down you odometer reading and fill up atthe same station to the same level several times, then do the math.

Second, one can drive for fun and pay at the pump, or one can drive for milege. Try driving both ways and compare the differences.

 

I dont know if I could do that scott...lol. I ust love hearing my engine, plus with the rb carb hat, its awesome. I can, just will be hard.

 

LOL, even at my age I have the same problem.

 

I get 400 - 600KM on a full tank. All city driving. http://www.rx7.org/public/1st-gen.html states that it is a 16.4 gal tank, which is roughly 62 litres. It all depends on how your driving. If your getting 150Miles/tank, that converts to 241 km. I beat the crap out of my car, and I almost always fill at 1/4 tank. I still have never gotten less than 350 km out of that. Even the last long drive I took I was doing about 150KMH (90MPH) on the freeway for about 150km one way, and didnt have to fill up til I got back. Of course my car won't go over 170KMH for some reason. If it could I bet my mileage would be much worse. It just sits at 4500 RPM and won't budge. Even downhill. Anyone know why this is? I was thinking at that speed the airflow isn't reaching the intake snorkel or is too turbulent. But I'm no physicist so I won't pretend to know for sure.

 

If my math is right, that's about 105 mph, it should top out a little higher, even with wind resistance. State of tune and engine compression #s usually come into play at these speeds.

 

My my mileage isn't that bad afterall. I looked at the factory manual I have and it says that the gas tank can hold 16.4 gallons which is 63 liters. When I filled the tank up last night I saw that it only filled up ten gallons. So, I still had plenty of gas left(6 gallons left). I dont wont to take the chance to get so low then clog the screen with the debris.

 

I don't really trust my fuel guage, as it sometimes seems to work right, sometimes it seems to work backwards, and other times it would just stay at one point, or go back and forth between another... lol so all the worse sypstoms ... I usually go by how many miles I go. It gets hard to guess sometimes especailly when i feel like stomping on it ... I usually try to keep track but sometimes its just too hard.

 

Thanks Trochoid. I'll be doing a tuneup as soon as I get her back on the ground. For once I'm only waiting for one part. Actually it should be here today if your 4 day window for delivery was correct. Otherwise I finally have everything I need. Right after I will be getting the few parts for a proper tuneup.

 

i get about 17 mpg but that is off of 13 gallons, i have an 85 gs and it stops at 13 gallons when completely empty so if it is supposed to have 16 gallons then why would it stop. Does this happen to anyone else.

 

Did you run it completely empty before filling it? Theres a chance your gauge float bottoms out a little bit before your actually empty. Either that or someone before you swapped to an earlier model tank.

 

How big are the tanks on the 79? I've filled up mine with like 8 gallons or so and that was bone dry according to the gauge which seems to work but I still get about 300 miles on the tank with mostly city driving and last time I took a trip I saw around 350-360 to the tank- I always thought I had a 10 gallon tank? Granted my gas milage is better via the fact I hardly ever get the rpm's over 3k and drive like I have no where to be so I take my time haha,

 

The tanks on the 79, Idk. The 80 tanks are 55 liters, 14.5 us gallons....so probably the same with the 79.

 

stock porting on engine, newer plugs/dist. rotor/wires/fuel filter, kn filter, stock carb, rb road race header with straight pipes.

I average 250-60 range to the 16 gallon tank with 80% city driving, 20% highway being my normal driving schedule.

On the tank I got 292 (personal best) I had 180 miles highway 62% (mostly spent accelerating from 65-85) and the rest was 112 city miles 38%, the entire time I was giving it a lot more pedal then I had previously ever and the mpg went up somehow. btw I averaged it out to 19mpg.

 

i think thats the case cause the gauge only goes to three quarters full and no further but i know the tank is the same cause ived dropped it myself to clean it out.

 

has anyone ever seen a increase in mpg when their revs inrease from normal?

I get the feeling that my FB sees the best mpg if I could cruise at 3,300-3,800 rpm all day on the freeway. I was previously under the assumption that the mpg would be high-er if I kept the rpms down in the 2.5-3.0k range.

 

I get my 23-24 mpg at around 4,000 rpm, 80 mph for 80% of the driving. I suspect I'm getting a lot better gas mileage at 80 mph out on the highway than at 45 mph around town. Also I filled up the tank this morning from pretty much empty, it took just under 15 gallons for my 84 GSL and I will get 350 miles out of it.

 

My stock '84 GSL has a 16.4 gal tank got 25 mpg on the highyway avg around 70 mph and could go 400 miles before demanding a drink. At least it did before I had the stock carb replaced with a Holley. Now I'm lucky to get 16 mpg on the highway. I'm going back to stock.

 

17mpg delivering pizza and i drive around 500miles per week so i know thats accurate for my 83 gsl all stock

 

Well, I filled my Gas tank up, pressed the calculator thing(forgot the name) and went away driving non spirited, but a few times I did. Well, I got halfway filled up again, and wenoff again not driving crazy all the time. When I hit halfway again, I wrote down the miles I have gone and got around 242 miles. So, its not bad afterall.

I would appreciate it if the people that are asking questions could do that somewhere else cause then the thread gets off the topic..Thanks.

 

I don't have time to read this entire thread, but wanted to mention this; make sure that your vacuum advance is hooked up to the most forward nipple at the base of the carb...

 

How much do you guys think hooking up the vaccum advance will gain in MPG? I should mention then that my post above is with the vaccum advance not hooked up.

 

I've been averaging about 2 mpg increase, but that is with the Sterling carb. With a stock Nikki, the results might be even better. However, the best thing about this (vac advance hooked up to 1st nipple) is that the car feels soooo much stronger when using small adjustments of the throttle. You just nudge the pedal, and the car surges forward. Before, I could only feel that kind of power at high rpms. It's like the difference between driving a 4 cylinder, then moving up to a high torque straight six.

 

I get an average of 18mpg 75%highway/25%city driving in my gsl with RB muffler setup and a more open intake. Carb is in dire need of a tune and rebuild though.

 

Kentetsu, Can you post a pic of the vac adavance and where you have it hooked up??

 

I'm plugged in to the 1st nipple, which is the one farthest forward on the base of the carb. If you stand by the driver's side fender, it would be the one all the way to the left. Hope this helps, cause way too busy with work right now to get any pics, sorry...