86 2.5 w/ automatic only gets 32 mmpg, good for about 300 miles per tank at 60-63 mph. How may one increase the cruising speed without affecting the mpg or increase the mpg at the same speed?
10k on new moly rings on a stock rebuild, 185/80-13 tires@36 psi, Bosch platinum gapped at .065"(anyone tried .070"?) Taylor wires, 12 degrees BTDC timing, new O2, 87 octane.
How much does minor alignment changes affect mpg?

Anything you can do to decrease rolling resistance will improve gas milage. Properly inflated tires, good alignment, good air filter and well greased wheel barings help. Insure there are no dragging brake calipers. 32+ mpg is pretty good for an automatic 2.5 Fiero. It sounds like your car is in good mechanical shape and gas milage does decrease after 55 mph.

Welcome to the forum, I wish I got 32 MPG, I guess having the 2.8 has some downfalls

A nice K&N air filter may help a little

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Josh Pics of my cars

Join New England Fiero Association

How can a K&N filter help at 2800 rpm? I though they were only good for more air at top end.
What kind of increase should one expect to see?

The original owner of my fiero said it got 35 miles per gallon on the interstate from West Virginia to Myrtle beach without failing for the 14 years he owned it, it made the trip 12 times and always 35 miles per gallon, and this is from a 2.8 v6 5 speed i was told they got about the same as the 2.5 because the 2.5 was less power to move a medium weight car, kinda like putting a 350 chevy in there, you got so much power you dont have to hit the gas much. just my thoughts

Who cares? It's a sports car, MASH IT!

If you want fuel economey, buy a civic.

Best!
Ben.

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

My 3.8 gets 18. 32 is unheard of around my place.

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http://www.fieroX.com

WELCOME TO THE FORUM 30+ !!!!!!!!!!!!!!!!!!

That's better than my 87 2.5 4cyl got. I got about 28 to 30 on a trip. 32 is great for an automatic.

Phil

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GTDude
25 years GM experience

Everyone seems satisfied at 32 mpg. :rolleyes
I had a friend that had a 86 w/ auto and stock rebuild that got 41 mpg on his 20 mile commute to work. I say we can do better than 32 mpg! How much does minor wheel alignment affect rolling resistance? What is the best setting?

My 3.1 2m4 is one of the lightest V6 fiero's (2660), running on 215X60r14 with the 4T60 Transmission, I pulled off a pretty respectable 33 MPG on a trip to florida and back, and consistantly runs a 15.1 @ 90 mph on the G tech. My Indy witch is a 2.5 with a 3 speed auto, got 33MPG as well, and did almost the same on emmissions as the 3.1L, but suffers through a quarter mile of 18.7 @76 mph, This car actually weighs the same as the 3.1 2m4. (this is a lesson on efficient motors)
My next goal is to still get 33+ MPG on my project, a 3800 series 1 NA, and do better on emmissions than both of my other motors. And push the motor to 200 horses with the 3 speed auto. Think its possible? we'll see in a few months. (carlisle?)

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Matt D
1984 Indy Fiero (auto)
1985 2m4 4T60, DIS V6 3.1 to be turbocharged

My car can't count that high.

30+.........your friend lies well.......41mpg............hahahahahahahaha. Maybe going down a very steep hill. No seriously.....it is not possible for a 2.5 to get that kind of gas mileage unless geared extremely high.....and especially in an automatic. NO WAY

Phil

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GTDude
25 years GM experience

My '86 2.5 automatic got 36 mpg on a trip from western Iowa to Ohio...anyone who has driven through Iowa on I-80 knows it's a roller coaster...up and down for 300 miles.

Secret is synthetic oil, clean air filter, good alignment and stock wheels and tires.

quote Originally posted by deceler8: My '86 2.5 automatic got 36 mpg on a trip from western Iowa to Ohio...Secret is synthetic oil, clean air filter, good alignment and stock wheels and tires.

What size wheels and tires where you using? What was your alignment specs?

A good four wheel Hunter alignment performed by a skilled mechanic runs about $180 these days. Well worth it IMHO.

Our two fieros typically average only 22-24mpg in the city, but on the highway my son's 5SP can get 39+mpg at 75mph - while my automatic is lucky to get 28-30mpg. It seems that the Fiero's automatic appeared before GM fully deployed 4SP overdrives throughout their product line.

Modern 4SPs are wonderful. We once owned a caprice which could reliably achieve 27+ mpg. Similarly, our 94 Roadmaster wagon does almost as well with just under 25mpg, and the 98 truck regularly hits 22+ despite it's lousy aerodynamics. The 700R4 and 4L60E make up for a lot of sins.

My suspicion is that a 2.5L Fiero with a 4SP would be good for at least 36mpg, since the 2.5L engine appears to be a very efficient powerplant with extremely low heat rejection. Those designers knew what they were doing when they built a "half small block", and the scans I've performed on their ECU show that they were very agressive with available ignition advance.

What rpm does your son's Fiero turn at 75 mph?

I think you are all dreaming......39mpg at 75 mph....come on.....lol. Yeah, and my 2.8 gets 35mpg at 90mph. Sorry guys, but I've never seen a 2.5 in anything get anywhere close to 39 or 41. I'd have to see it to believe it.

Phil

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GTDude
25 years GM experience

If you don't have anything positive to say ...why say it?

Just searching for a reality check around here.......there seems to be none.

Phil

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GTDude
25 years GM experience

I once slapped a man for asking what the gas mileage of my ferrari is...

Yeah, I think reality (no, not you with the purple car left this thread long ago.

Best!
Ben

quote Originally posted by GTDude: Just searching for a reality check around here.......there seems to be none. Phil

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

My 84 2.5lwith 4.10 was getting 27 to 29 at 75mph (60miles each way to work)

My 88 GT gets about about 27 LOOKS per mile.

My 84 with 4.10s get 22mpg on a norm. day. One time I got 27 on a highway trip. Man, what a nice feeling that ONE time was...

You know, I don't even know what mileage my car gets. I think it's in the 20-ish range (I can typically go ~200miles before empty.) But I really don't care.

Maybe it's a sports car thing.

Best!
Ben

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Ben Cannon
88 Formula, T-top, Metalic Red. "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver, In-Progreess. -Mel Gibson, "Braveheart"

quote I once slapped a man for asking what the gas mileage of my ferrari is...

Did you buy the Ferrari for $1,200 like I did my 86 2M4?

I've been driving my parent's 86 2m4 3sp auto 80 miles a day for awhile now. It had 43K on it when we bought it last year. Now it's got 64K. New tires and alignment. My torque converter is out and I drive 70+ on the interstate and the best I've done is 31 or 32 when I first started to drive it. I need to check around on it because now I'm getting around 24-27.

I could get 24 with my 87 olds 307 4bbl carb. and with my formula firebird (both autos). My personal best was 500 miles per tank w/ my moms S10 in the city (5sp). Works out to 30 some odd, close to 40 I think.

Anyway, not that this helps but my point is I think you are around par. You might be able to squeeze some more out, the 36 sounds about right, but I don't think it can do much higher. Stock that is.

How far are you willing to go to improve it?

The settings for toe, caster and camber all have ranges. On a stock 2M4, what value within each spec will yield the lowest rolling resistance?

quote Originally posted by artherd: Who cares? It's a sports car, MASH IT! If you want fuel economey, buy a civic. Best! Ben.

Come on Ben, would you appreciate someone interrupting a thread of yours about better brakes with a comment like "who cares, it's only a commuter" ?

[This message has been edited by DRH (edited 03-05-2002).]

Kosei K1s are a lighter wheel ( www.tirerack.com ). along with a 70,000 mile tire (420+ treadwear) and slightly elevated tire pressures would yeild better MPG.. less rotating mass and less tire deflection what kind of weight reductions have you done? the stock camber but pull some of the toe out of it.. find a good reputable alignment shop and speak with thier technitian while your cars on the rack. do you use your a/c? that belts wasting MPG if the a/c's not functioning.

edit---
what oil are you using? Synthetic usually helps. (helps on the dyno i'm sure it'd help for MPG too.) i'm with them on the K&N too. it flows better at any RPM range...
https://www.fiero.nl/uploads/BlackGTdyno.jpg - dyno results help a little the entire rpm range.

[This message has been edited by 1FST2M6 (edited 03-05-2002).]

Katys daily driver, 400 dollar 87 2.5 5 speed gets 33MPG. Doesn't seem to care where she drives. City or interstate. My daily driver is a 86 SE 4 speed with 215,000 miles gets 32 on the hy and 22 in town. My 87 GT 5 speed can't bust 23 no matter what. Go figure!

Don't call BS on anyone. The truth is out there and it's wierd.

A clean waxed car gets better gas mileage.
Narrow high inflated tires get better.
Windows rolled up get better.
Staying home gets the best, if your going for the gold but ........

I,d rather be in Archies stinger with a stop at every station.

How about the tranny? I'm not sure, but I'm guessing a fresh unit will be more efficient than an older one. Just a thought. Not sure how far you want to go. Feel free to ignore.

Wouldn't one of the easiest things to do be a bigger tire? I mean assuming you've optimized the engine performance already as per previous suggestions to tuning, air filters etc. And the rolling resistance is of a minimum, then the next logical step is to make the motor turn fewer times per unit of distance. I say bigger tires since altering the gear ratio is kinda tough. Anything you can do to get the rev's down will only help.

I do my own wheel alignments, using a spool of white thread, a tape measure, 4 jack stands, a plumb bob, a flat concrete indoor floor, masking tape, a pen, viener calipers, a level, a square, a caster gage, patience and the nut & bolt suspension tools per "How to Make Your Car Handle" book. So give me the toe, camber and caster numbers for front and rear and I can crank them in myself for $0.
+{]:O) < Bless you!

you want better mpg?
convert it over to propane

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Rich
Sioux Falls SD

are all fieros money pits, or just on-going projects??

No propane for me. Thanks for the suggestion.

306.4 miles on 9.3 gallons at fill up today. First click off of gas pump was at a little over 8 gallons. This evening, I opened the gap on the Bosch platinum plugs to .070" from .065". After a thousand miles 3 of the plus were just starting to show a small tan line on one side. The fourth had a pink spot on one side. The rest of the center electrode insulator was still bright white.

With the car below, I get 35+mpg at (70mph fwy/some city mixed in), and about 32mpg at (75mph fwy/some city mixed in).

Right now I have fat 205-55-15s on all four corners. The tires are inflated to 40psi.

If you put skinnier higher profile tire, I'm sure you can eek out 1 or more mpg.
KV

1987 SE 4-cyl, 5-spd

My moms grand prix 90' , has almost 300,000km on it and it gets 37mpg highway that is just amazing it's a 3.1lv6 , and you notice how far it goes..

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My 3DO site!!!

www.geocities.com/thereal3do

need some feedback!!! not done yet :)

Swap in a 4 speed auto of some kind. I think there is one that is a bolt in swap, although some wiring changes may be required. Don't ask me for more information, because... I really don't give a rat's latter half about automatics.

My '87 GT 5 speed got 30 once. I was tooling around at relatively low speeds (55-65) on the interstate north of Washington DC on a trip to Delaware.

Did the 2.5 come with an auto four speed? My TH125 gives me 2700 rpm @ 60mph. With a .705 overdrive, the revs would drop to about 1900 rpm. Does the 2.5 have enough torque at that rpm? HMMMM, at 5000 rpm that would be 157 mph. Now that's really FAST!!