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best engine for fuel mileage?


GrayZee

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I was thinking of buying a house out of town (60miles) but I figure with the price of gas the driving back and forth will really start to dig into the ole wallet after a while. I don't really want to buy a s**t-box econo car, so I was thinking of a nice Z that with a powertrain that has mileage in mind rather than power. Anybody have any ideas?

How would you get a Z to give you 30-50mpg @60mph?

Maybe 50mpg is just plain impossible... I dunno.

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Guest greimann

That is an interesting project. Typically people on this board are trying to figure out how to pour more usable fuel into their engine, but some performance modifications and economy goals go hand in hand.

 

Attempting to get 50 MPG from a Z car would require an assult on all factors that affect total vehicle econmy. Things like weight, rolling resistance, aerodynamic resistance, and engine effiiciency all combine to affect your mileage.

 

In the engine area, I would think you would want to start with the smallest displacement available (240) and combine it with an aftermarket fuel injection to get the best fuel management possible. Install headers, free flow exhaust, free flow intake inhaling warm air for better fuel evaporation.

 

Strip the interior and exterior of any unnecessary equipment to get the weight down to bare minimum (like removing the spare and carrying a tire plug kit and compressor.)

 

Install skinny, tall tires like 185-80R 14 and pump them up to 50 PSI.

 

Smooth the exterior by installing headlight covers and a small rear wing to separate the airflow at the tail.

 

Econmy is a question of money, how much can you afford to save?

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Guest zthang43

And don't use an automatic either; a stickshift is way better for mileage.

A T56 might be pretty good for mileage with that tall 6th gear overdrive, but by the time you bought that you would be spending more than you save.

To help the gearing (since tall gearing gets better mileage) use the tallest rear tires you can, while still keeping them skinny. I don't even know if such a beast exists, but a 195or205/90R15 would be just right. A 205/90R15 should be almost 30 inches tall, according to the tire size calculator I made in excel. Compared to using 205/60R15's with a 3.56 rear, a 205/90R15 would be like running a 2.98 rear gear, which would help your mileage considerably.

All that said, I don't think you will get 50 mpg. Something like a Chevy Sprint gets close to that, but weighs way less, uses a 3 cylinder, and has 13 inch wheels that are like 155's or so.

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Guest Anonymous

High MPG engine:

During the gas crisis of 1970's, Crower Cams

create a V-4 chevy kit. It utilized four dummy

pistons. With only four cylinders in operation,

it was only 175 cu inches. As I recall, the fuel

mileage was in the 25 mpg range. The vehicle was

a Camaro about 2900 to 3000 lb weight. So I

guess 30 mpg in a zcar would be possible.

 

Sunny

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Guest bang847
A 260Z with a 1977 350 V-8 rated at 180 horsepower and a late model automatic overdrive transmission will do 0 to 60 mph in under seven seconds and get over 22 mpg on the highway
and that is JTR's estimate.. isnt that pretty good?

besides you dont want a econobox car but if you force a Z to get good milage isnt that worse? smooth driving civic or stumbling Z?

get a disel rabbit.. those get close to 40mpg?? plus you should score a used one for $5-600 now thats cheap!

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I'll offer my $0.02 on this topic. I have a L28ET with a T5 and a 300ZX (Z31) ECU. I do 0-60 in 5-6 seconds, 1/4 mile in high 14's (at 5800 feet - intercooler going in soon), and I get 27 mpg averaging 80mph. I got this mileage going from Denver to Grand Junction (250 miles) in about 3 hours. This included an incredible pull at 9000 feet, passing a left lane hog up an 8% grade at 115mph. :D

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Guest Anonymous

I'll throw out a unusual choice for a engine that still will get good mileage yet give you a bit of performance.

 

How about a turbocharged 2.3 litre Ford motor out of a thunderbird turbo coupe? With a overdrive 5th in such a light car (compared to the Tbird its in) should net you great mileage (if it doesn't get close to 27-28 mpg I'd be very surprised, maybe closer to 30).

 

Any of the later model fuel injected engines (4 cyl or V6) should net you pretty good mileage in such a light car. How many MPG are you aiming for? Good luck with it.

 

Regards,

 

Lone

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This may sound like a bad choice but since your not looking at performance and you want fuel mileage, try diesel. They had diesel maximas, no reason why they wont fit in a Z car. Only problem i see is where your going to get a diesel maxima donor. cheers.gif

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With any of these things you're going to spend more money than you save. My 70 240 gets 26 MPG now. If you want to improve on that a cheap 4 banger is probably the answer. Shouldn't a Nissan 4 cylnder out of a 510 bolt right in? You could probably pick one up at a boat yard since about all they are good for is boat anchors (haha). No really, they should be pretty cheap. I've heard of people going the other way (a 2.4L 6 into a 510) but never the other way around.

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Geo Metro. A friend just bought a 1996 with 80,000 miles on it for $750. If he drives like a sane man he gets 56 mpg. If he drives it like a looney (85 mph all the time on the freeway - in a Geo) he gets 42 mpg.

 

We're seriously thinking about entering that car in GRM's 2003 Challenge. We've got a line on a wrecked Hayabusa and we did some measurements on the Metro engine bay. We also corner weighed the Metro and the cross weights are almost perfect at 49.9 and 50.1 with driver. Total vehicle weight with driver is 1770 lbs.

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Originally posted by johnc:

If he drives like a sane man he gets 56 mpg. If he drives it like a looney (85 mph all the time on the freeway - in a Geo) he gets 42 mpg.

85mph?!?!?! In a Geo?? I used to have a 1990 Suzuki Swift, (I'm not sure but I don't think they had those in the US but it's basically the same car) I don't think I would have wanted to go that fast for any length of time I'd be worried about the engine going *KABOOM!!* My Suzuki was a good car overall, but I didn't care for it in the winter-time because it took forever to get heat and even though it was FWD it was still too light to have any traction in the snow. Can't complain though, I bought it for $500 cuz it didn't run and the owner couldn't figure out why. (turns out it was the fuel pump fuse was missing) Ran great and needed a few other things but I drove it for a year or two and sold it for $1700 :D Some days I wish I would have kept it just for the gas mileage! Oh well, the $1700 went towards the paintjob on my Z ;)
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Guest Anonymous

Yeah the swift was around for a few years in the states (maybe longer I donno), I remember seeing it at the Isuzu/suzuki dealer when I bought my truck back in '89 and traded in my Samurai. Suzuki also has the new Aerio (I think thats what its called, this may be a older model I just havn't heard of) coming out at dealers, they've gone upscale a bit with cars like the Grand Vitare SUV. To bad the Escudo isn't available, check its specs.. (I know it has nothing to do with mileage, but its interesting!):

 

escudo4.jpg

 

Description/Information:

 

Curb Weight: 1764 lbs

Layout: Mid-Engine/AWD

Transmission: 6-Speed Sequential

Type: Twin-Turbo V6

Displacement: 1998 cc

Horsepower: 985 bhp @ 8100 rpm

Length 5050 mm / 198.8 in

Width 1900 mm / 74.8 in

Height 1510 mm / 59.4 in

Valvetrain DOHC 3 Valves / Cyl

Tires 285/680-17 - 285/680-17

Bhp / Liter 492.99 bhp

Transmission Sequential 6 Speed

 

The car had TWO turbo charged V6's one in front, and one in the middle. It could run well in excess of 200 mph ( how about close to 245 to be precise :eek: ) all wheel drive and it was driven it on pikes peak where it won two years running, the Japanese driver must quite possibly be the craziest racer to ever step foot in a car. Kids don't try this at home. nono.gif

 

Now back to the topic, sorry. :D

 

Regards,

 

Lone

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I can't find my '72 240Z factory service manual right now, but in it is a single 2 bbl. Hitachi carb version of the 240Z. I've got one of these rareintake manifolds. The Hitachi may be no good, but I could include an adapter for a downdraft 2 bbl. Weber (DGV 32/36 type), and these carbs are readily available. I would sell this aluminum Nissan manifold and Weber adapter for $60, plus shipping. I know the 2 bbl. setup was used on L20A engines in Japan. It was on an L26 in a '72 240Z that I bought long ago. I remember the car was quick to fire up and very driveable.

I remember seeing a car magazine article once with an LD28 in a 280Z. The cast iron cyl head and fuel pump assy. are HEAVY, to the point you would need stronger front springs. However, the diesel exhaust ports are standard square port and a turbo manifold would bolt-on. This, with an intercooler, would be a high mpg, unique car. You'd need to bolt-on a rear sump pan (L28ET). DAW

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I'd lower the car, attach a very large front air dam, add a 5 speed, keep skinny tires at high psi and concentrate on my driving technique. And slow down, the number one cheapest and easiest way to improve mileage! :D You have to make a HUGE difference in gas mileage to save any real money compared to what any of the major engine swap mods would cost you, since you are only talking about the difference between what you have and what you want. A TPI 305 and a 5 speed should get 30+ mpg in a Z at 65 mph and still run 13's... My buddies '74 Corvette convertible with a swapped in TPI 305 and TH700R4 went to Houston, ran a 13.97 and averaged 27 mpg on the way down there. Usually the car runs real consistent 14 teens which ain't bad for a 3700# car with a 305... The 3800 V6 swap and a T5 should get you better than 30 mpg as well, but you have to control your right foot and keep the speed down. Donors for the V6 are really cheap compared to the V8 cars.

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Guest Anonymous

A Silvia motor like an Sr20det would likely get good power/economy. It is on of my more favored 4-cyls (heh.. cuz Nissan makes it).. You could easily land 14's with near 200 horse, and probably tune the motor to ~30mpg otherwise. Can't say it would be the cheapest though.. I saw one a few months ago for $1400 including efi stuff, believe it had about 100k on it. Hate the thought of losing 2 cyls though.. sour.gif

Honestly I'd try and tune a L24 to get high 20's mpg.. do some of the other things people suggested and save on the expenses of getting a whole new motor.

As a personal note I'm building up a 300+hp l28et and likely running 255 tires, but I'm hoping to get around 20-25 mpg if I keep my foot out of it and use low boost around town. With SDS I'll probably try tuning it both ways.. power and economy. Can't wait to see how things go.

Good luck

-980mak rockon.gif

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"I'm hopeing to get 20 to 25 mpg if I keep my foot out of it" Yea! 980mak tell me another bedtime story!!!!! :D:D when monkey's fly!!!!!!! :D:D

I'm sorry that was just a knee jerk reaction. Couldn't help myself malebitchslap.gif

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