z-ya Posted April 6, 2004 Share Posted April 6, 2004 My completely stock 78' 280Z: 28MPG on a trip My highly modified Turbo 240Z: 20MPG if I'm lucky Pete Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted April 6, 2004 Share Posted April 6, 2004 ...can maintain a good 80mph most of the way... Try going 60 or 65 or so and you'll get even better! Remember drag increases as the square of the speed. Hopefuly your car has a 0.0 Coefficient of drag... ? At 40 mph, you'd probably get 50 mpg, unless you fell asleep. Quote Link to comment Share on other sites More sharing options...
zero Posted April 6, 2004 Share Posted April 6, 2004 oh yea, on the trip from florida, we pretty much kept it under 60 due to a pretty bad shimmy. that may have played a part in our mileage Quote Link to comment Share on other sites More sharing options...
510six Posted April 7, 2004 Share Posted April 7, 2004 In 6th gear at 70mph and driving without getting into boost 28mpg was the best I could do.But, the car was only turning 1600rpm. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 7, 2004 Share Posted April 7, 2004 Okay 65 then. But I'm putting $20 that says I dont get more than 23mpg's. IF I can even really do this... actually looking like I wont be able to take any long drives this weekend Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted April 7, 2004 Share Posted April 7, 2004 That's why the speed limit on the Az highweay was 125 mph- 300 miles of nothing, so going faster takes less time & less sleepy. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted April 7, 2004 Share Posted April 7, 2004 Well this is really going to piss some people off then. My spedo is tested true and accurate with several of my friends cars. I run 2.8L slightly shaved head, 1mm head gasket, Nissan racing cam, racing valve train, ported and polished head, MSA headers, 2.5" exhaust into a magnaflow flow through muffler. Intake i'm running triple 40mm Webers. I get 18 around town as long as i don't drive like an idiot. And on my 550 mile trip from Houston to Lubbock and tweekd my car to 27mpg and that is doing about 85-90 down the highway and i feel i can squeeze it up to 30 with a little more tunning. Your OEM stock Z's arnt going to get as great milege as some of the modified cars on here. stock Z's suffered from poor intake and exhaust flow. When you open that up the engine can breath, anything helping the engine breath better is going to increase your gasmilege as long as you don't drive like an idiot. Also mentioned was 4 banger imports barely squeezing out 30+mpg. My g/f 94 honda accord bone stock got 37mpg on the same trip. Just wanted to set the facts straight. One of the main reasons why the 4bangers suffer for mpg on the highway is the short gear ratios running 4k at 80. Something to think about. Ed Quote Link to comment Share on other sites More sharing options...
Phantom Posted April 7, 2004 Share Posted April 7, 2004 OK guys - I am absoulutely anal about recording everything that is done to my Z cars - and that includes logging every gallon of gas I have ever put in them, filling them to the brim with each fill-up, and calculating exactly the MPG each time based on the reset tripometer. My totally stock NA 5-spd. 83ZX averages 19-22 mpg in combined city/highway driving with the variation based on the season (lower in the winter) and the number of highway vs. surface street miles. I also found that if I use 2,500 rpm as my shift point and maximum speed in each gear, that I can nurse another 10-14% in fuel economy. I deliberately ran a two month trial to determine that. I'm an engineer. The numbers are based on controlled variable conditions and are accurate - Not guesses based on what the fuel gage said after a certain number of miles. My NA '77 280Z averaged about 18-21 and the LS1 conversion now averages 18-21 under the same conditions. These are not guesses or estimates. They are numbers derived from 12 years of data and precise calculations. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 8, 2004 Share Posted April 8, 2004 OK guys - I am absoulutely anal about recording everything that is done to my Z cars - and that includes logging every gallon of gas I have ever put in them' date=' filling them to the brim with each fill-up, and calculating exactly the MPG each time based on the reset tripometer. My totally stock NA 5-spd. 83ZX averages 19-22 mpg in combined city/highway driving with the variation based on the season (lower in the winter) and the number of highway vs. surface street miles. I also found that if I use 2,500 rpm as my shift point and maximum speed in each gear, that I can nurse another 10-14% in fuel economy. I deliberately ran a two month trial to determine that.I'm an engineer. The numbers are based on controlled variable conditions and are accurate - Not guesses based on what the fuel gage said after a certain number of miles. My NA '77 280Z averaged about 18-21 and the LS1 conversion now averages 18-21 under the same conditions. These are not guesses or estimates. They are numbers derived from 12 years of data and precise calculations. [/quote'] see now those numbers are believable, and he's actually really going out of his way to make sure they are accurate. It's funny how some of you are so certain that revving it higher gets better mileage... and the reasoning for that does in some ways make sense, and yet others always seem to get better mileage driving it as gently as possible. I definately got better miles shifting early, about 2500rpm, at 19mpg's, vs the average 17 I get normally shifting at 3000 and getting on it. I WILL make it a point to take a long freeway trip as soon as I can... Betting on like 23mpgs for that one. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted April 8, 2004 Share Posted April 8, 2004 I WILL make it a point to take a long freeway trip as soon as I can... Betting on like 23mpgs for that one. Just make sure it is a freeway outside of LA....LA freeways are the same as surface street when it comes to stop an go driving....actually surface streets are often better than the freeways.... Tim Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 8, 2004 Share Posted April 8, 2004 oh yeah of course yeah thinking of a trip up the 101 to santa barbara, probably pretty late at night since that's when me and my wife are up nowadays, both working the night shift. heheh are you kidding man most LA freeways during rush hour are worst than the damn surface streets! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted April 8, 2004 Share Posted April 8, 2004 no such thing as rush hour anymore....rush hour is from 06h30 to 21h00 on the 405.. Tim Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted April 8, 2004 Share Posted April 8, 2004 My numbers are acurate as well as my fuel gauge does not work, all i use are numbers. And the way i have my car tuned it get's better milege over 80 than under say 70-80 compared to 80-90, I think has to do with the rpm range, cause around 80-90 the came produces the most torque, so it kinda makes sense in that way. -Ed BTW city driving my max shift point is 3k, usually take first to that and progressively shift lower each gear, 2nd at 2700, 3rd 2500, etc. (this a 5spd as well) Quote Link to comment Share on other sites More sharing options...
twoeightythreez Posted April 9, 2004 Share Posted April 9, 2004 My 78 280z gets about 17mpg in the city and about 25mpg on the highway (as long as you keep the engine speed above 2,500rpm) with the 1981 280zx n/a trans. I'm not running rich, but I do burn lots '0 oil. I didn't calculate mileage by the speedo (which actually is very accurate until you go past 90mph) but by a trip using the mile markers. My Z has a 17.8 gallon tank. The 1974 and earlier Z cars had 16.0 gallon tanks (and I know that for a fact...the 71 I had ran out of gas and it took exactly..umm...SIXTEEN GALLONS) Think of it this way...A V-8 won't get worse mileage, so why not? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 9, 2004 Share Posted April 9, 2004 16 gallons??? Okay then something is wrong with my tank or gauge because there is no way I'm fitting 16 gallons in my '72 tank. With the gauge at or below 1/4 tank I can put no more than 10 gallons before it is completely topped off, where I can see fuel in the filler neck. Can anyone else verfify the size of the 240 tank??? Quote Link to comment Share on other sites More sharing options...
twoeightythreez Posted April 9, 2004 Share Posted April 9, 2004 You could always verify it yourself, you could just have a VERY PARANOID sender..these cars HATE running outta gas! (you don't want to know how long it took me to re-prime my fuel pump on the '71!) The '72 has a drain plug on the bottom of the tank. Simply drain the gas out when you're too scared to risk driving any farther and measure it! Actually...I believe Datsun/NIssan put them in the tanks until the Late 80's, then stopped (if there's any measure of what's happening in the world that's one of them, can't have a drain plug on the tank anymore, if people knew about it they would drain all your gas just to see you stranded!) In fact the Frontiers still have the dimpled area on the bottom of the tank where the drain plug used to be! (The frontier's frame harks back to the mid-80's!) Quote Link to comment Share on other sites More sharing options...
fl327 Posted April 9, 2004 Share Posted April 9, 2004 My average on the freeway and street is 23mpg, if I only drove freeway it would be ALOT better than that, but once I hit the streets, I HIT THE STREETS. z cars really do hate being empty dont they? The one time my car ran out of gas and I put a gallon of gas in it to start it, fuel filter clogged on me and I would idle at 1500 with no kind of acceleration, I thought it was my distributor giving me problems. I changed the fuel filter, and I picked up 8psi fuel pressure at idle!!!!! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 9, 2004 Share Posted April 9, 2004 Well there is one reason I DO believe the accuracy of the fuel gauge. I'm running my fuel feed from the bottom of the tank, similiar to what a lot of turbo'ed 240's have when they choose to retain the stock 240 tank. The only real problem with that setup is when the tank get's too low if you take a turn hard the fuel will move off of the feed and you're pump will suck air briefly. I figure the tank has to be really low to do that, and it's only happened to me the couple times I've run lower than about 1/8th tank according to the fuel gauge. But that is pretty subjective 'evidence' I guess. Ah well... even if it does hold 16 gallons, I can't ever run it lower than about 1/8 due to that fact, and I know no matter what that it will never take more than 10 gals to fill it up from that point. *shrug* so the knowledge that it may be holding 16 doesn't do me much good but at least now I know! Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted April 9, 2004 Share Posted April 9, 2004 There are 2 possibilities ( as Spock would say) for error when you use your fuel gauge to determine the colume in your tank: 1. Your fuel gauge could be wrong, either at the sender end or the gauge end. Typical of the old equipment. 2. Your fuel tank is not a perfect "cube." You can't depend on your fuel gauge to show the volume unless the tank has square sides that are all the same height and width, and the cross-section must also be the same all the way down from the top! Just look at a picture of the tank in your assembly manual. It's shaped like an inverted oil pan. That means the level goes down faster at the top and slower at the bottom. I can only get 75 miles on the first 1/2 tank and 200 on the second half?? the only sure way to use the fuel gauge to figure the volume of fuel in the tank is to fill it up when the gauge hits each mark. Better yet. find out how much to fill at every 1/10th tank. Every 1/100th tank. Still, the gauge isn't consistant... Please don't make any more claims about fuel mileage using your fuel gauge as a volume gauge, unless you measured it scientifically. Of course, it still is a good idea to know how far you can go when it gets down to 1/4, so you can make it to the next gas station too sense. -Spock out Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted April 10, 2004 Share Posted April 10, 2004 When my gauge hits empty I still have 4 gallons of gas left in the tank. The tanks are supposed to be 15.8 gallons. later,norm Quote Link to comment Share on other sites More sharing options...
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