txbeaux Posted April 17, 2008 Share Posted April 17, 2008 I bought my 280z a long time ago and have made many changes over the years. Driver, Racer, Parking Lot Rallies, Old School, New School..on & on. Today the car has a stock 1983 turbo long block with original 78 stock EFI & some suspension work. It's about time for paint, minor rust & body work, along with mechanical update. I am interested in hearing opinions about 25 or 30 or more miles per gallon while still retaining a little pep. I know there's a bunch of you that have ideas about making the Z more pump friendly. It's about more than just your right foot! Quote Link to comment Share on other sites More sharing options...
Challenger Posted April 17, 2008 Share Posted April 17, 2008 From what Ive seen moving to a stand alone will really help. Your able to control your fuel/air ratios anf therefore able to get better mileage. Ill find one of the threads that disscussed it. Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 17, 2008 Share Posted April 17, 2008 Garrett is putting well over 400hp to the wheels (430 or so iirc) and he's getting 30mpg on a good tank. The real key is standalone. If you're getting BAD gas milage there's a good change the ECU isn't going into closed loop (using the O2 sensor) and even when it IS in closed loop the air/fuel ratio will have a tendency to wander quite a bit as the ECU has a hard time keeping the ratio at 14:1. 30mpg seems to be the reasonable limit for most guys though, regardless if they have 200 or 400hp. The main difference obviously is how much gas is consumed when they're ON the throttle. Why did you keep the 78' EFI? Didn't want to deal with converting over the 83' wiring? To me that's a huge step right there. The 83' ECU isn't very good, but I can't imagine a 78' NA ECU trying to manage a turbo motor. I'd recommend either looking into a standalone, or upgrading to a Z31 MAF based ECU. The Z31 swap can be done for cheap, but you really want to make sure you know what you're getting into before hand. There's a sticky about that swap on this board somewhere. Probably close to the other stand alone sections. Options for standalone are plentiful, and they all have their pros and cons, but many people here go with megasquirt because it's cost is far lower than other standalone systems. It has a lot of the same advanced features as the high end stuff too, and it's well documented here. Quote Link to comment Share on other sites More sharing options...
txbeaux Posted April 17, 2008 Author Share Posted April 17, 2008 I blew a head gasket some years back and had this turbo long block in the shop just waiting for something. I stuck it in for now and that was probably 4-5 years ago. I've never gotten over 22 mpg, even when the car was bone stock, had practically no miles and I was much younger. I'm sure it was the foot thing back then. Quote Link to comment Share on other sites More sharing options...
txbeaux Posted April 17, 2008 Author Share Posted April 17, 2008 I've read about the mega-squirt AND the 4 barrel conversion from Arizona Z but mostly people talked about performance & reliability as opposed to fuel mileage. I have been leaning toward the 4 barrel, getting the P90 head & the block reworked as per "BRAAP". The 4 barrel conversion makes things real simple and at my age, I don't know that I will want to rebuild this car again in 10 or 15 years, just enjoy it! What kind of mileage are people getting with the 4 barrel? Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 17, 2008 Share Posted April 17, 2008 I just realised the motor is NA at the moment... Makes more sense now... I was thinking you were running not just a turbo longblock, but entire turbo motor on the 77' EFI. Well the 4 barrel conversion is certainly easier than megasquirt I'd imagine. Though a lot of guys here swear by side draft carbs, like mukini or webbers. Though it might seem harder to setup carbs that need to be synced they offer pretty good performance in the long run. There's a pretty long milage thread if you just search for gas milage you should find it. Very few guys with a L series engine get under 20mpg or over 30mpg. I also know a lot of it has to do with what speed you're cruising at. Don't expect great gas milage at 70+ or anything over 3k RPM. Quote Link to comment Share on other sites More sharing options...
blue72 Posted April 19, 2008 Share Posted April 19, 2008 I just calculated my gas mileage from my most recent long distance trip. A tad over 25mpg. My setup is an l-28 +1mm overbore with '72 su's, early 5 speed and 3.9:1 rear end ratio. I was taching 3500-4000 rpm most of the way (75mph = 3700rpm). I'm interested to see what will happen with a port and polish and bigger carbs. Quote Link to comment Share on other sites More sharing options...
txbeaux Posted April 19, 2008 Author Share Posted April 19, 2008 blue72...Interesting point here. "A tad over 25mpg with 3.9:1 gears." Here's another place to find fuel mileage, shorter gears in the rear end with some sacrifice of low end pep while still retaining a top end. IMHO, I would think that P & P would be a small bang for a big buck. This is something an expert like "Braap" might like to cue in on. Rumor has it, he has reworked a head or two. Headers, Exhaust & Carbs would probably do a lot more for a lot less $$$. Quote Link to comment Share on other sites More sharing options...
naviathan Posted April 19, 2008 Share Posted April 19, 2008 Economy in a Z can be had by changing the rear to something a bit taller like the 3.54 (which you might already have) and using the standard L28 5 speed from a ZX which has a wider ratio gear set and updating the EFI. MegaSquirt is not all that hard to do, and with the wealth of info on this forum anyone can do it. Definitely get rid of the stock EFI harness and go with the universal 12' from DIY Auto Tune to simplify the swap. If you go with this setup it should net you close to if not at 30mpg. Keep your foot out of the firewall and you might do better. Quote Link to comment Share on other sites More sharing options...
ktm Posted April 19, 2008 Share Posted April 19, 2008 Garrett is putting well over 400hp to the wheels (430 or so iirc) and he's getting 30mpg on a good tank. The real key is standalone. 30mpg seems to be the reasonable limit for most guys though, regardless if they have 200 or 400hp. The main difference obviously is how much gas is consumed when they're ON the throttle. I am now getting around 30 mpg and am putting down 320 ft-lbs at 15 psi (more now with meth and 20 psi ). I agree 100% that the key is a good stand-alone system and tuning, tuning, tuning. Quote Link to comment Share on other sites More sharing options...
txbeaux Posted April 19, 2008 Author Share Posted April 19, 2008 Could you say, with everything else being equal, that a standalone system, properly tuned, would probably be more efficient (MPG) than a 4 barrel (ie. ArizonaZ) properly set up or is it just a coin toss? Quote Link to comment Share on other sites More sharing options...
Gollum Posted April 19, 2008 Share Posted April 19, 2008 EFI well tuned will ALWAYS be all around more efficient than a carb. A well tuned carb can almost always make close to the same peak power as EFI, but it can't be fine tuned like EFI can. The great thing about EFI is that you can tune to get MAX power at ALL RPM, not just one, and still get good efficiency/gas mileage when you keep your foot out of it. Without EFI getting over 100HP per liter naturally aspirated like in the honda S2000 would be impossible, as every tank of bad gas you bought would probably destroy your engine. Carbs simply can't compensate for the variables like EFI. That being said, there's plenty of guys here running carbs that are well tuned that get near the 30mpg mark, I just wonder how much power they're leaving on the table. Quote Link to comment Share on other sites More sharing options...
txbeaux Posted April 19, 2008 Author Share Posted April 19, 2008 Well said! Quote Link to comment Share on other sites More sharing options...
terrycoxusa Posted April 30, 2008 Share Posted April 30, 2008 I have the Holley/Arizona Z manifold setup. I'm very happy with it, the only problem I have is a bog if I floor it, especially when cold. Other than that, it starts great hot or cold and runs well. If you do the Holley conversion, buy a brand new one and don't mess around with a used or rebuilt, it will save you time and money. I haven't checked the mileage, but I've put about 2500 miles on it with no problems at all. I agree that a properlly set up injection system would get closer to the perfect fuel/air mixture at all throttle settings, but I had a 280z with injection and the Holley seems quite a bit peppier, probably because the factory efi is tuned to run as lean as possible. Quote Link to comment Share on other sites More sharing options...
Daeron Posted May 2, 2008 Share Posted May 2, 2008 I can't recall the stock compression for a turbo engine, but wouldn't it run dog-weak, therefore causing you to put more foot into it? Even if the difference in compression is not that substantial, it probably plays a factor.. Methinks you would gain fuel economy not just by switching to megasquirt, but also by installing a turbocharger on that thing Alternately, you MIGHT be able to use the megasquirt to tune in an ULTRA economy setting and get her up to 30, 35 mpg.. I have been giving alot of consideration to an ultra economy L series engine, and what it would take to do it. Seeing what you could do with a lean fuel map for a lowball block would be interesting.. and is certainly nothing that cannot be changed later. Quote Link to comment Share on other sites More sharing options...
sticky280zx Posted May 2, 2008 Share Posted May 2, 2008 7-3-1 i think is the stock turbo numbers which like daeron said should have no backbone at all....till like 3k and without a turbo wouldnt be much better up top Quote Link to comment Share on other sites More sharing options...
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