Hot_Dog

I took the old RX7 on an 892 total mile road trip this past weekend to Charlotte's zMAX Dragway for the NHRA 4-Wide Nationals. I been going to the 4-Wide Nationals at CMS for the past 4 or 5 years. This was probably one of best competitions that I've ever seen. There was lots of action at the strip this past weekend.

A week prior to this road trip, I performed some minor maintenance to get the car in shape. I replaced my fuel filter, which IMO is always a PITA. Its been about 1-1/2 years or 16k-17k miles since I last changed the fuel filter. I replaced my reverse/5th gear switch. My backup lights stopped working probably sometime in January. The old switch had a closed circuit resistance of about 220 ohms. Not sure if this high resistance was also affecting the 5th gear switch. I replaced my O2 sensor with a Bosch universal O2 sensor. My CEL light would intermittently flash on/off while driving. This problem was going on for several months. Pulling error codes would give me a code 17. Well, a number of years ago I found that my O2 wire somehow had broken off near the harness. I reattached wire using mating 1/4" spade solderless wire connectors, which at the time was intended to be only a temporary fix. Well, I finally replaced this wire with mating 1-pin pigtail connectors that I soldered to the wire at the harness and the other end to the O2 sensor. This fix finally solved my CEL problem. Apparently, the high resistance at the old connector was causing this error code. Lastly, one of my tires was always losing a pound or two of air every couple weeks. It turned out that one the valve stem was slightly loose. These simple fixes lead to a noticeable improvement in throttle response, overall performance and gas mileage.

I gassed-up 5 times during this trip. I made sure that the tank was completely full with gas almost overflowing during fill-up. My gas mileage during this trip was:

Miles Gallons MPG Type driving
173 8.8 19.7 City/Hwy
341 14.8 23.0 Hwy
64 3.7 17.3 City/Hwy
334 13.5 24.7 Hwy
77 3.0 25.7 Hwy

Driving style: I was typically driving about 5 MPH or so over the limit while occasionally using cruse control. I would occasionally take her up to 80 or 85 MPH for a few minutes.

Weather: The temps were mostly cooler than normal with windy conditions.

During previous road trips, I've gotten 23 or 24 MPG but never 25.7 MPG. I'm not sure why this mileage was so high, but I'm not complaining

On another note, I did find an excellent brewery in Charlotte's North End. The brewery is called N.o.D.a. and is located in an old factory building on North Tryon Street. They must have had 20+ beers on tap. My preference is usually IPA type beers. I especially liked their Hop Drop 'N Roll 7.2% ABV IPA and Hope Cakes 10.2% ABV Imperial IPA. N.o.D.a.'s distribution is essentially limited to the Charlotte area. I made sure to bring several 16 oz. 4-packs back home with me for purely medicinal purposes. Actually, I'm drinking one now as I'm writing this report. Cheers!

mazdaverx713b

iTrader: (91)

Honestly, I'd say those mileage numbers are excellent! Sounds like it was a fun trip. Did you take any pictures during the trip?

clokker

iTrader: (2)

The variable that separates your best mileage from the other two highway runs is the distance covered.
It's likely that had you been able to go 300 plus miles instead of 77, the mileage would be more in line with the first two segments.

Hot_Dog

Yeah, that's probably the case. Yesterday, I managed to dig up my old '90 Mazda RX7 dealer brochure to check the EPA mileage estimates. They were listed as 17/25 (City/Hwy). I was surprised that I was able to meet the 25 MPG hwy mileage. From a performance standpoint, my car is primarily stock except for the exhaust (Bonez high-flow cat and RB cat back) and rear end (4.3 R&P and clutch type LSD).

Hot_Dog

I snapped only a couple photos. Here's one at the start of Sunday's race. Top Fuelers doing burnouts prior to a 4-wide run. Top Fuelers putout 10,000+ HP each and run sub-four seconds reaching speeds of over 330 MPH with runs limited to 1000 ft. in the US. You get four of these beasts running side-by-side and everything around you starts rumbling.

littlebit421

Miles Gallons MPG Type driving
173 8.8 19.7 City/Hwy
341 14.8 23.0 Hwy
64 3.7 17.3 City/Hwy
334 13.5 24.7 Hwy
77 3.0 25.7 Hwy

Ya know, those are some pretty good numbers. I went to DGRR this past weekend and on the highway I averaged between 22 and
24mpg, the funny thing is, I have most or some of my emissions deleted, aftermarket exhaust header, and 5th and 6th ports removed. I always hear people say that the fuel mileage goes to crap when you do these things but mine has maintained pretty good. I did not see a drastic drop in fuel mileage after all that, people made it sound like I would get like 12 mpg but really have not seen a difference.

Hot_Dog

Interesting...I would have thought the same about emissions removal.

mazdaverx713b

iTrader: (91)

Fuel mileage usually drops a few mpg when removing the emission rack and components. There have been horror stories of poor idling conditions that are not able to be corrected easily. Perhaps its all in the quality of the work. I prefer my cars to be original. That's just me. I don't get quite that good of mileage out of either of my 88 NA's and will certainly not out of my 10AE. I do think that highway distance does matter over the course of the tank. I drive my 88 SE mostly in the city and the mileage is crap.

Jager

iTrader: (10)

Sounds like an interesting trip!

Nice mileage numbers too btw.

Hot_Dog

Yeah, the drive is about 400 miles, or roughly 6 hours, from DC area to Charlotte. Charlotte Motor Speedway (CMS) is a nice motorsports complex with a NASCAR track, zMAX drag strip and dirt track for truck races. I'm debating whether or not to drive down there again later this month for either the All Star Race (May 19th) or the NASCAR race (May 27th). I've been to the NASCAR race once before and it's the longest NASCAR race at 600 miles. I might do the All Star Race this year to avoid the Memorial Day weekend holiday traffic.

Red95FD

iTrader: (3)

I am jealous of those numbers.I get 17 mpg in my 88TII and that's when I baby it. I get 12 mpg when I drive with a heavy foot. Lol I get 31 mpg on the hwy in my 84 12A which balances things out but I'd rather drive the turbo. Cool trip by the way. I'm like Dave, I like stock but I do have a catback on the TII.

Hot_Dog

Theoretically, you are correct. But, I think that Clokker was referring to the sensitivity of mpg on number of gallons per number of miles traveled. If miles traveled are relatively low, than a small change in gallons consumed may lead to relatively large change in mpg. For example: 77 miles / 3.0 gal = 25.7 mpg. However, for 0.1 change in gallons: 77 miles / 3.1 gal = 24.8 mpg. So, an additional 0.1 gallon upon fill up will lower mpg by nearly 1 mpg. This is more in agreement with my 334 mile run.

Hot_Dog

Well, the rotary wasn't exactly known for its "great" gas mileage. Maybe that's why it's not available today? BTW, my mpg goes to $hit when commuting to/from work everyday.

NCross

iTrader: (18)

Crap! Missed DGRR again...