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Iron Duke + 3 Speed Gas Mileage by Firezappy
Started on: 08-14-2018 03:14 PM
Replies: 11 (234 views)
Last post by: Dennis LaGrua on 08-17-2018 11:57 PM
Firezappy
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Report this Post08-14-2018 03:14 PM Click Here to See the Profile for FirezappySend a Private Message to FirezappyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Honestly I was impressed today. I have been averaging my mileage when I go to work, and I have been taking my Fiero. It's a 1988 3 speed 4 cylinder. By driving with a light foot I averaged 30.3 mpg, about 40 minutes highway and 20 minutes city each way. Might be a big help that I am in Ohio, so often highway speed is only 55 mph. For a 30 year old car with a 3 speed transmission and a cranked up ac, I am very impressed. Idles a little high at start though, going to carefully look for intake leaks.

What do you guys average? Really wonder how big of a difference the manual makes. Also would like to hear about how much the 6 cylinder gets.
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Raydar
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Report this Post08-14-2018 06:14 PM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
My 88 Duke with the automatic only averaged low 20s.
Keep in mind, that this was in/around Atlanta, where everyone drives 80 MPH. The only way I could avoid being run over was to drive it with the right pedal flat on the floor.
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armos
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Report this Post08-14-2018 10:45 PM Click Here to See the Profile for armosSend a Private Message to armosEdit/Delete MessageReply w/QuoteDirect Link to This Post
My 84 3spd auto, 14" wheels 3.18 final drive, I remember getting low 20s.

It was a long time ago and that car was a beater. I was driving in areas with more stoplights, colder weather, and with a strong cultural tendency to race from stoplights (*way* more than that happens today where I live). Gas was cheaper, I drove it hard, and towards the end it had a performance cam installed. It burned oil and eventually learned it had bad compression on 1 cylinder. I did some hacky stuff in the engine compartment, because I was young and didn't know much what I was doing (but in my partial defense, neither did much of the 1990s internet).
I have fond memories of that car, but it was in bad shape and I was hard on it. So it got low 20s.

I still get the same low 20s now on my v6 with 15" wheels, 3.33 auto (works out to the same overall ratio). It's a much healthier car than my 4cyl ever was, and I don't drive it as hard.

[This message has been edited by armos (edited 08-14-2018).]

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theogre
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Report this Post08-15-2018 02:18 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Firezappy:
Honestly I was impressed today. I have been averaging my mileage when I go to work, and I have been taking my Fiero. It's a 1988 3 speed 4 cylinder. By driving with a light foot I averaged 30.3 mpg, about 40 minutes highway and 20 minutes city each way. Might be a big help that I am in Ohio, so often highway speed is only 55 mph. For a 30 year old car with a 3 speed transmission and a cranked up ac, I am very impressed. Idles a little high at start though, going to carefully look for intake leaks.

What do you guys average? Really wonder how big of a difference the manual makes. Also would like to hear about how much the 6 cylinder gets.
I have gotten 28-30mpg w/ 87 dis duke w/ auto. Some 84 and 87/88 have 2.84 "finals" w/ 4 cyl engine. Most times I get 25-27mpg going to work and other local places.
Right now TCC lock solenoid is bad so can't lock the TC and mpg is lower driving on the highway.

Other has 2.84 final but the final gearing is not the only thing affecting total gearing for most auto trans cars...
See my Cave, Gear Ratio

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Evil88
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Report this Post08-15-2018 11:33 AM Click Here to See the Profile for Evil88Click Here to Email Evil88Send a Private Message to Evil88Edit/Delete MessageReply w/QuoteDirect Link to This Post
My 1988 Duke with Isuzu 5-speed on a trip from Fort Worth to Omaha got 36 mpg. This was on cruise control the entire way only stopping for fuel with a tail wind. On the way back to Texas 34mpg with a head wind.

Edit: Opps, just realized this was a thread for the 3 speed auto.

[This message has been edited by Evil88 (edited 08-15-2018).]

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Dennis LaGrua
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Report this Post08-15-2018 04:53 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
A neighbor who once owned a Duke with the 5 speed claimed 39-40 hwy mpg. That was years back when the engine was low miles and in perfect shape. Sounds like the claim might have been exaggerated a bit as that figure would be excellent 30 years later.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
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armos
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Report this Post08-15-2018 07:22 PM Click Here to See the Profile for armosSend a Private Message to armosEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dennis LaGrua:

A neighbor who once owned a Duke with the 5 speed claimed 39-40 hwy mpg. That was years back when the engine was low miles and in perfect shape. Sounds like the claim might have been exaggerated a bit as that figure would be excellent 30 years later.



Perhaps exaggerated, but I remember lots of people claiming 40mpg on manual 4cyl cars. However, that was usually for 84 4spds with rare economy gearing, not the 5spd.
40mpg+ cars have been around a long time, there just wasn't much demand for them. There's more demand and government mandates today, but it was achievable without all the modern high tech bloat.
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Firezappy
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Report this Post08-15-2018 10:02 PM Click Here to See the Profile for FirezappySend a Private Message to FirezappyEdit/Delete MessageReply w/QuoteDirect Link to This Post
I really would have wanted to have had the 4 or 5 speed manual, but after a few months of searching this 3 speed was just so cheap and just under 100,000 miles. All original, no mods of any type, original stereo etc. theogre, your Fiero Cave website is so in depth with good information on gear ratios. Almost makes me want to try to get a larger narrow tires for mpg. I just really like this car aesthetic, since I have the three speed duke it's not like this car will ever be fast without a swap anyway.
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Curtisk1060
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Report this Post08-15-2018 11:23 PM Click Here to See the Profile for Curtisk1060Click Here to Email Curtisk1060Send a Private Message to Curtisk1060Edit/Delete MessageReply w/QuoteDirect Link to This Post
I don't mean to hijack this thread but on my way from Colorado to the 35th Anniversary meeting in Peoria, I was able to get nearly 31MPG during one stretch while travelling 80 mph with my 3800 SC and the 4t65eHD overdrive transmission on cruise control in my 88GT. Overall, I averaged about 27.7 mph for the entire trip including the stop and go traffic and the cruises for the entire 2300 miles driven. This was its longest trip to date and it performed flawlessly. At 80 mph, my rpm's were 2400 to 2500 rpm. What a great show and for me a good road test for the car.. Curtis

[This message has been edited by Curtisk1060 (edited 08-15-2018).]

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JMTUT
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Report this Post08-16-2018 11:16 AM Click Here to See the Profile for JMTUTClick Here to Email JMTUTSend a Private Message to JMTUTEdit/Delete MessageReply w/QuoteDirect Link to This Post
That is great mileage for most cars in real world driving. My 85 duke with a 5 speed averages 20-21 mixed driving. The best I've ever gotten was 26 on the freeway.
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silver 85 sc
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Report this Post08-17-2018 09:51 PM Click Here to See the Profile for silver 85 scClick Here to Email silver 85 scSend a Private Message to silver 85 scEdit/Delete MessageReply w/QuoteDirect Link to This Post
I used to get 38-40 highway in my '85 Duke automatic. 28-32 city. I really miss that car. After 22 years of daily driving there wasn't much steel left under that plastic skin.

Rich
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Dennis LaGrua
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Report this Post08-17-2018 11:57 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you are in fact getting over 30 mpg wit ha Duke and the three speed TH125 then I would not complain . Just stay with it.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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