What gas mileage should I get?

[84GNwith87eng]

Read my sig for my combo, car runs very well, no misses and is very reliable.

I filled it up, and it looks like I've gone 100 miles on 1/3 tank so far...(my fuel gauge has been a little more accurate since the s/u was cleaned)

Does this sound right? Or will I end up getting <200 miles/tank like usual? My old combo was getting around 175 miles/tank with 30#, stock turbo and a half decent tune. Car runs 10x better now, so what should I get?

Bueler?

 

[441120]

It depends, all city driving and a heavy foot 12-15 mpg. Driving miss Daisy on a flat mid-western interstate 25-27 mpg. I get 18-19 avg little city a little highway, and it's a little hilly around here.
My 1969 GTO with a carb and 400 ci gets more than 200 miles a tankful

 

[VadersV6]

If I totally stay out of the throttle and "drive miss daisy", I get 17-18mpg highway. My TC lockup doesnt work so theres 2-3mpg maybe right there Im not getting. The tune is practically perfect with no bad parts that would affect mileage. I was getting 8mpg when I bought the car. It was really really ****ed up. Running on 4 cylinders, a 7.5" rear end in it with 4.56 gears, cracked header, sensors and ignition all jacked up, 3800 stall non lock converter. Whats funny is that switching to stock gears and a stock TC didnt improve my mileage AT ALL. By fixing all the sensors and ignition parts and getting the tune right with new injectors, I got all the way up to 16mpg with the high stall TC and 4.56 gears. Then after spending 1300 on an 8.5" rear with stock gears, I was PISSED when the mileage didnt improve. Figured...ok, its the converter. Pulled the tranny and replaced it. NO improvement. Im jealous as hell of the people who pull 26mpg out of theirs. I just dont see how.
When it comes to mileage, gears arent as big of a factor as people think. I got 20mpg on the highway with 390hp and 4.56 gears in my cobra. The mileage didnt go down at all when I went to those gears. I think its cause the gears make the engine move up into a more efficient range in the rpm band. Focus on ignition problems...#1 offender of gas mileage in my book, and then the O2 sensor, then exhaust leaks, then making sure the injectors arent hanging open and making sure the tune is right and verifying you're in closed loop. Then make sure you have TC lockup.

 

[pacecarta]

I filled it up, and it looks like I've gone 100 miles on 1/3 tank so far...(my fuel gauge has been a little more accurate since the s/u was cleaned)

gas mileage is defined by the simple term mpg , broken down that is miles per gallon or mathematically miles/gallon , to figure this number you have to accurately know how far you drove not i have 18 gallon tank and i show half on needle so i used 9 gallons to go 100 miles , is doesnt work that way . most gauges seem to take a while to run out the top half of the tank but then the needle seems to move fasyter as you get toward the bottom , doesnt mean your mileage is getting worse , it means thats the way it reads , remeber mileage is MPG not needle moved half its miles per gallon

miles being first part of the equation , to be accurate means having correct speedo gears in the transmission for the tires and rear gears that you are running .
for example if youve got 28" tires instead of the stock 26.1" tires your mileage will be off approx 7% ,odometer will show 7% less than you've driven so factor this in

second part needed to compute MPG is gallons , repeat gallons , not how far the needle on your fuel gage moved , to compute gallons used by your car fill tank and record mileage at fill up then drive about 100 miles or better two hundred and refill tank noteing mileage driven and gallons needed to refil tank . do this over a few fillups and keep notes , when you have a few fillups take and average the mpg over about 500 miles , the more miles the more accurate your MPG # will be .

as vader found out his search for better mileage to save a few bucks he would have been better driving it as i beleive he spent way more to find economy than he will recoupe in ten years (maybe 20) , but in his case the car was a mismatched nightmare and to be enjoyed it needed to have years of changes to his car repaired and/0r brought back to what they were .
keep the car in proper tune and mileage will come
,

btw i see about 18 mpg normal around town and 24mpg highway with the TT chip , injectors wont cost you economy if chip is burned correctly , but as HP increase you will use fuel faster when you put your foot into it ,

 

[VadersV6]

as vader found out his search for better mileage to save a few bucks he would have been better driving it as i beleive he spent way more to find economy than he will recoupe in ten years (maybe 20) , but in his case the car was a mismatched nightmare and to be enjoyed it needed to have years of changes to his car repaired and/0r brought back to what they were .
keep the car in proper tune and mileage will come

Well it wasnt about mileage and saving a few bucks as much as it was, driving around with a TR that has 4.56 gears making me cruise at 3400rpm, a TC thats slipping so bad that my tranny is overheating and smoking out of the fill tube, a rear end that will snap under high boost, an engine running on 4 cylinders when there are 6 that I can count, a dead O2 sensor, sensors either no good or out of adjustment, etc. If you have a bad ass 9 second car thats getting 8mpg, fine. I can see that. It was built for that. But if its a 14 second car that you have to drive 70-80 miles a day, Id rather do it right and have a well tuned car. I guess its just me. I dont like driving around in a car that sounds like a 50 year old farmtruck stuck in 2nd gear with exhaust leaks and smoke coming out of the tailpipes.
Its not saving a few bucks when you're getting another 10 miles down the road with every gallon of gas. From 8mpg to 18. This is a 125% improvement in mileage. Nothing to scoff at when you drive 70 miles a day. It wont take 10 years to recoupe my money. I already earned it back in spades. I also didnt spend alot of money to do it. It was mostly a matter of adjusting what I had. The injectors, MAF and chip came with the car on the side. The new header cost me 40 bucks. The TC cost me 60...mostly all cheap fixes, but labor intensive. By far the most expensive thing was the rear end, which had to be done and really had nothing to do with mileage. I dont like half assed cars with mismatched parts. I know you understand that most of my fixes were done to get the car back in shape, but I took exception to the idea that my efforts toward economy were wasted efforts. Not when its a daily driver and you put alot of miles on it every day.

 

[pacecarta]

dont get me wrong , im not picking on you but your threads consumed the board for quite a while and will forever be the end all thread to seeking out mpg as every time you looked deeper into the car it seemed there was more screwed up stuff than any one person would ever encounter ,
but if you go back to your first thread you stated you cant afford to drive this car due to the poor mpg , so it was about the money , im glad you got it all squared away and can enjoy the car and you do drive it , but for the average guy who doesnt daily drive recouping what you spent would be hard

 

[441120]

... a half decent tune. Car runs 10x better now, so what should I get?

Bueler?

18 mpg :biggrin:

 

[VadersV6]

Ok. Let me re-phrase what I originally wrote about the car. I could afford to drive it, but I didnt want to have to. I found it ridiculous to spend 24 dollars per day to drive to work and back. Now I spend 12 dollars a day (because of the increase in the price of gas.) Had I not fixed the problems, I would be spending 29-30 dollars a day on gas because of this rise in gas prices. Had prices not shot up, I would be spending $10.50 per day now, as opposed to the then, 24 dollars a day. But lets see what Im saving now, in reality.
$24-$12=$12. $12 per day saved...and thats just driving to work. I also drive 20-60 miles on the weekend, but I wont even count that. We'll say I only drive 5 days a week. $12 saved per day. 5 days=$60 saved. 52, 5 day work weeks per year (I dont take vacations)= $3120 saved. This is based on a 70 mile route, but for 8 months the road leading to the freeway was blocked and I had to take a 6 mile detour. I was actually driving 76 miles a day. If you add the 60 miles on the weekends, thats 440 miles a week as opposed to my numbers based on the 350 mile route. We're looking closer to $4000 saved a year.

recouping what you spent would be hard

What I spent? It wasnt alot. The rear end cost me $1300 installed with boxed LCA's, a new driveshaft and new bearings and a new axle....and the rear end did nothing to improve mileage. I wanted the original rear end in it. Thats all. I was going to do it regardless of whether I was getting 1mpg or 90. Everything else was very cheap and I did all the labor myself. We'll say all that **** cost me $700 at the most, on things that I did to improve mileage...probablky closer to $400.
Had I sat on my ass and enjoyed the ****ty running car, I'd have $2000 less in my pocket last year, and 4000 less this year.
So it'll take me 10-20 years to get my money back?
Now that Ive made you nauseous with my OCD, I know for the average joe who drives a GN on the weekends, it wouldnt be like this. But since when is having a good running, fast, gas efficient car, a bad thing? Even if I drove 20 miles a week, I would still want the car to run right and be efficient. Part of the allure of having a GN is that its not only fast, but it gets good mileage. If I wanted an 8mpg car, I would have bought a 64 Nova with 4.56 gears and a 6-71 blower sticking out of the hood. But you would probably think that the nova gets ****ty mileage and is a poor choice for a daily driver, while if the GN gets 8mpg, you think its ok for some reason...."8mpg?...eh, why bother fixing it....itll take you a century to make your money back if you buy a new O2 sensor to fix it" :biggrin:

 

[84GNwith87eng]

dont get me wrong , im not picking on you but your threads consumed the board for quite a while and will forever be the end all thread to seeking out mpg as every time you looked deeper into the car it seemed there was more screwed up stuff than any one person would ever encounter ,

i thought you were talking to me for a second...lol...not far off anyway

 

[84GNwith87eng]

pacecarta, were you at the hooters meet a while back? I was there too...

 

[87geeinn]

Similar setup as yours @ 19-20mpg on a damn near perfect tune. That's with 90% highway driving ~70-75 mph with maybe 2-3 WOT blasts on the weekend.

www.fueleconomy.gov rates our cars @ 25mpg hwy and if you've ever owned more than one car and compared the governments ratings and/or window sticker ratings, you will never reach that rated mpg figure unless you do all your driving while accelerating slowly, setting the cruise at exactly 60mph on the highway with a tailwind and no city driving.

Remember, the saying goes, "It's just a six," not, "It's just a four-banger." 18-19mpg on a heavyweight car with a v-6 is not that bad at all considering the power they generate even at stock levels.

 

[Blazer406]

I am currently getting around 20 with mods in my sig..... 60/40 highway... town...... mileage has been as high as 23 on a babied tank.... and as low as 15.5 or so..... on a tank that I didn't cut it any slack..... :biggrin: ...... but mostly... it gets around 20 MPG..... I am currently driving my GN 80 miles roundtrip a day.... and loving every minute of it.... :biggrin:

 

[TurboTnZ06]

I have a heavy foot and I'm getting 18 mpg. I thin kanywhere from 15-20 is normal. Above 20 is good.

 

[VadersV6]

Damn i was a high strung angry bastard yesterday. I used about 9000 too many words to make the point. Anyone ever buy "wake the **** up" coffee grounds? Jesus Christ I had a cup of that coffee yesterday and it was like I had a lightning bolt rammed up my ass. My heart was skipping beats and all sorts of fun stuff.

 

[Quiky One]

I get about 15 in town 23-25 on the highway with close to the same mods. So I say your a little better off than me.

Jason