I will be using my Fiero as a commuter car. I'm looking for way to increase fuel efficiency. I have a few ideas but I want to make sure I don't screw anything up so I figured I would run it by ya'll 1st.
Is there anything to be had to delete the catalytic converter? Will it screw anything with the computer up? The only other thing I can think of is a high flow filter. What else is able to be done to the Old Duke to get some better MPG.

Thanks,
Andrew B.

Well i have a suggestion talk to Proff http://www.hawkesburyhydrogen.com

Lower the car

Chin Foil..... Is it really a foil or spoiler?

skinny tires at 45 psi

recessed hood scoop

syncromesh if its a manual

Power pullys

maybe ratio rockers

and most of all...Tune-Up and drive it with a light foot.

Steve

I am getting around 30 MPG with my 86 2.5L and manual transmission, but that is mostly highway driving with a little city driving. When I had the same engine hooked up to an auto trans, I got around 25 MPG.
It really beats my Ford F-250 which gets 10 MPG!
How can you make that better? Keep your foot out of it, which is easer said than done...
Use good gas, light oil, 5W30, remove all unnecessary weight from the car, every ounce counts! Keep tires slightly overinflated, tune up with fresh plugs and timing check, keep your windows up!
So many little things help with mileage, but it helps with a car that gets good mileage to begin with.

[This message has been edited by crashyoung (edited 06-28-2012).]

Our worn out 85 2.5 and isuzu got 30 city and 40 highway without much hassle (except noisy and slow).

My '85 duke got consistent 38 mpg highway and 30 city she was an auto 142,000 when rust finally claimed her. Nothing special was done to the car. Kept everything greased and the tires inflated, and ran the ethanol blend fuel. Before I rebuilt the engine at 117,000 miles I could get 40-41 mpg with the timing advanced another 2 degrees and running premium.

Rich

My 88 2.5/auto averages about 25-28 on my 19 mile daily commute (each way), but haven't ran it enough on the highway yet to know that mpg. Eventually, I will be swapping in an isuzu to improve the mileage some more.

Inflate the tires to a point that you can stand the harsh ride. On 87 & 88's run the factory spark plugs, make sure you have good plug wires like GM/Delco, PCV valve replaced, change air cleaner & keep it fresh, if it is an 88 make sure your brake caliper sliders are free and the pads are off the rotor, run a higher quality gasoline, not higher octane but a better quality fuel., get a good four wheel alignment, if you want to and dont mind the look, run narrower tires, especially up front as the standard front bumper cover tucks in and leaves the tire exposed to cause drag. Put the Indy/GT front bumper cover on for aerodynamics and cover the front tires from wind causing drag.
Oh drive 65 to 67 not 70 on the expressway. My son an automotive engineer tells me ALL the forces associated with vehicles increases expotencially.
Well I am failing asleep typing this and the POS dell laptop is cutting out. I can think of more ideas, I'll let you know.


Steve W.
NE Grand Rapids, MI
88 Coupe

[This message has been edited by solotwo (edited 06-28-2012).]

What are you getting now, and what year is your car, is it a manual trans?

So me getting 30 MPG while driving 80 to 85 MPH is good mileage?
So hard to keep a lightfoot... Gordon...

42 mpg highway 2 summers ago on a trip to Pittsburgh. 86 duke 5 speed. That's also running premium on that particular trip. If you want better MPG than that, you will have delete some weight.

[This message has been edited by tbone42 (edited 06-29-2012).]

Make sure you guys are using gps or freeway mile larkers to verify your speedo. We thought we were getting 40 with an 86 2m4, turned out the speedo was off and we were only getting 35.

How much are you looking to spend?

Review of a Modified Duke

45MPG average with a heavy foot.

[This message has been edited by Rallaster (edited 06-29-2012).]

quote Originally posted by bkaab: I will be using my Fiero as a commuter car. I'm looking for way to increase fuel efficiency. I have a few ideas but I want to make sure I don't screw anything up so I figured I would run it by ya'll 1st. Is there anything to be had to delete the catalytic converter? Will it screw anything with the computer up? The only other thing I can think of is a high flow filter. What else is able to be done to the Old Duke to get some better MPG.

Year? Transmission?
RPO(s) number for trans? (Auto gearing are listed as RPO.)

Engine is about good as it is.
Trans can help MPG, power, or both, a depending on gearing.

Unless it's blocked, Removing cat won't help MPG or power. Current model does not cause restrictive exhaust.

See my cave,
gear ratio in trans section.
AOD convert in option section.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Well I just bought the car and with my 1st fuel up it was getting 29mpg with 2/3 highway kind of beating on it since I just bought it and wanted to figure out how slow it was and how it handled.
The car is a 1985 with a 5 speed Isuzu. The car just had the spark plugs, wires, cap, and fuel filter changed by the past owner but I don't know what he put in it. Right now the car has 13" rims and 175/70/13 tires on them. The trans is out of a GT so the speedo gear is set for the 15" rim and tire combo. So my odometer and speedo are about 11% off. So I can either change the speedo gear and still be a little off since the tires are small then stock since they no longer make that size or I can move up to a bigger rim.

[This message has been edited by bkaab (edited 07-03-2012).]

Best bang for the buck if you have solid 87 or 88, it can be done on an early car, but you must be more careful. Pull the head, and get it shaved down I'd say .015 to raise the compression. 10-1 would probably be a good start. You may need to run premium fuel, but the trade off should be an easy 40mpg while cruising at 80mph. We had a local club guy, who modded his 87 Duke Auto, he was an older hotrod guy, in his 60's so he took his old Cosworth train of thought to it, raise the compression, get more air in, and more air out, the thing would scream, just as fast as a V6 Fiero 0-60 but got better fuel mileage than the stock dukes. There is a lot more to do beyond shaving the heads, but getting the compression up is your best bet. Then run the lowest grade fuel that does not freak out the knock sensors. I had an 88 Coupe that I really wanted to play with, but I already had an 88GT and an 87GT, So I kept the 2 GT's and sold the coupe. My V8 gets 30mpg on the highway and my 88GT 2.8 gets around 32mpg on the freeway. However I was really looking forward to 40mpg.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

https://www.fiero.nl/forum/A...030531-2-018929.html

When I took a long trip in my '88 Iron Duke, the best mileage I got (38 mpg) was along a stretch of high-altitude highway in Idaho.
So my advice is to always drive at altitude.

My 86 2.5 5spd with 330+k miles on it is doing 26 city, 35 highway. Admittedly, I haven't given it a full tuneup/going over yet. I'm also pretty light on the throttle (on this one )