What kind of gas mileage do you get? For me it is about 25mpg, with about 80% of my driving on the highway. Engine: 2.8L, no mods - just stock Trans: Getrag 5-speed To be completely honest I expected better from a tiny, lightweight car with a little engine. I don't drive like a grandma, but also not very aggressively.
Just out of curiosity, what are you guys getting and with what drivetrain?
I was getting 22 city/ 28 highway with my 1985 SE V6 4 speed.(1985-1998)......In 1999 I installed an F-body 3.4 long-block under the stock 2.8 FI system and a Getrag 5 speed...also installed 86-88 GT rear quarters and an 87-88 base car nose...Now I get 20 city and 30 highway.
I drive no more than 5 mph over the highway limits and yet I drift the car through most turns (If noone is around)...Also, I always look ahead and if I'm approaching a red light I cut the throttle early.
The Fiero is not really a lghtweight car, and keep in mind that the engines are ancient technology, pushrod, iron block and heads.. so gas mileage won't be great
I actually get better gas mileage with my 3800 SC motor than I ever did with the 2.8- not sure why
I was thinking about back to the future and Delorean and Mr Fusion and how it is real. Fill plastic waste into pyrolysis reactor heat to 100℃ to 250℃ use the carbon biproduct process into fuel oil by distillation plant. Add hydrogen and it is all free. If you have a garbage tip worth of rubbish around.
The Fiero is not really a lghtweight car, and keep in mind that the engines are ancient technology, pushrod, iron block and heads.. so gas mileage won't be great
I agree.... The later versions of the small V6 got better mileage. The Gen II and especially the Gen III engines with SFI get surprisingly good mileage.
I have a 3.4 Getrag fastback. Locally, I get about 18 mpg, but on a long road trip running cruise control, I've hit 33. Some of my fill-ups show I'm making about 21 mpg if I'm making trips that include 4-lane highways. I live in a very small county that's not more than 20 miles wide in any direction, so there aren't but a few miles of 4-lane in the county. All surfaace roads.
I have a turbo push rod 3.4 and two 3800 SC (II and III) engines in cars and I get around 26 mpg on average when running the A/C. All are coupled to Getrag 282 transmissions and I use high test fuel.
The Fiero 2.8 should break into the low 30s on the interstate with the 5 speed. Tire pressure, alignment, engine condition and state of tune will all impact fuel economy.
I have a 86 SE with a Getrag and hit around 28-31 on the highway without ac but once, just once, got an even 36 mpg on a trip. Just over 100k on the engine.
My daily driver 2.8 with Isuzu 5spd gets an average of 27. High of 34 (all flat freeway and adhering to speed limits), low of 21 (all short trips in the city). If my windows are down economy drops to 23ish and not because of the drag. My exhaust really starts to come alive around 3000-3500 RPM lol. Also, I had some meatier tires on it last year and dropped economy down about 2 mpg. Wheel weight makes a big difference!
My SBC 350 V8 with Getrag gets 17 usually, I've gotten up to 23. Swapping to direct fuel injection with 6 spd transmission this spring and hoping that will bring it into the 20s regularly.
I had a Duke for a few years with Isuzu 5 speed and averaged about 33mpg.
I don't do much city driving with my 3800SC . It has a few mods and is mostly driven on hwy to shows in PA and a few local cruise nights. On the hwy with the car fully loaded, (trunk extra full), and with the A/C running the gas mileage varies from 26-28 mpg. The mileage would be higher but my 87GT is heavy with the intercooler system (pump, heat exchanger, IC unit, reservoir and coolant) , welded muffler, tool box, leather seats, S-10 booster and three fire extinguishers. When we go to Carlisle or for an overnight my wife also likes to stuff the car full of her stuff. When I attend an out of state show alone the mileage is higher.
------------------ " 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 "
I have an 07 3.9 lz9 and on the way to the 35th strictly highway driving I was getting 34-36 mpg.
Wow! Besides fuel economy, would you say the lz9 is a good engine to swap in? I know I'd like to ditch the 2.8 eventually, but haven't yet decided what to swap in. Of course I'm strongly considering 3800 NA or SC, Cadi 4.9, and 3.4 DOHC, but those engines are getting harder to find as they get older and it might be advantageous to get a new engine anyways.
Wow! Besides fuel economy, would you say the lz9 is a good engine to swap in? I know I'd like to ditch the 2.8 eventually, but haven't yet decided what to swap in. Of course I'm strongly considering 3800 NA or SC, Cadi 4.9, and 3.4 DOHC, but those engines are getting harder to find as they get older and it might be advantageous to get a new engine anyways.
Oh hell yea. The 3.9 and 3.5 are easy to find. Same gm fwd bolt pattern and have great power. Chris at Schwa motor spots swapped mine and has done multiples since. We use micro squirt as a stand alone ecm. Mine has ls valve springs to eliminate float. Northstar throttle body to convert to cable vs drive by wire. We estimate with that alone I’m around 275 hp. These engines also take boost very well with little upgrades from there.
I have 2 4.9 conversions, one 5 spd getrag and one a 4spd auto. They both get 19 city and 30+ on the highway. My 2 four cylinder cars get about 21 city and 35 highway at 60mph. Above 60 mph the highway mileage drops off due to high rpm'. Both of the 4 cyl cars have 3 spd auto.
DIY MPG counting is harder then many think. A best you have to count over Several to Many tanks because most don't fill at same station w/ same pump and follow exact same steps to operate the pump. Just the nozzles will shutoff at different levels of filling a tank. Even if all nozzles at same station are new and from same batch of nozzles can change shutoff points after a few months because idiots drop them etc. This can change Full level for a given car ± ½ to 1 gallon. A change of ± ½ for small tank like Fiero can change Calculated MPG a lot. Example: Say tank needs 9gl every time... many nozzle shutoff lower to much lower, only some get close or over. 200 mile / x gl = "MPG" and watch "MPG" change as x goes 8 to 9.5.
⚠️ Warning: Do not "stuff" the tank! Stuffing means Nozzle has shutoff, often several times, and still trying to push more. This can over fill the tank and cool/cold fuel will expand and force fuel up the EVAP Vent and could poison the EVAP canister w/ Liquid gas or worse make a gas leak that can burn the car down. If you think a Nozzle has problems, Don't try to force gas into even a empty tank. Complete the sale and go to a different pump or another station and try again. Even if Everything is 100% good, Some nozzle Hate some cars and keeps shutting off and then most have no clue when actually full. (Nozzle assemblies may look same or are same but small differences you can't see easy can make a nozzle not to work in some to a lot of cars.)
Total Trans gearing will affect MPG... Lower total = more gas eaten even if car and engine is 100% same otherwise. Stick cars is main gear x final = y:1 Auto is harder... main gear x chain set x final = y:1 that y:1 changes quite a bit every year just for OE Fiero then add whatever trans use for given engine swap. If change tire size will make true MPH harder to count using normal methods and trip odo. See my Cave, Gear Ratio
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Originally posted by statue4: Does a stock 3800SC run regular gas, or does it require high octane?
Find Owners book for car the engine came from. BUT... If ECM/PCM has any programming mods or different computer used then that won't help because can change timing etc require high to max octane gas.
knocking can destroy an engine.
------------------ 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)
All I'm gonna say is this, if you want better fuel mileage, slow the heck down.
I haven't checked the fuel mileage on a Fiero in years but, I'm constantly monitoring my fuel mileage in my Ram Diesel. The cost of speed is fuel consumption.
I can effect the fuel mileage in my Ram as much as 7 to 8 mpg depending on how much of a hurry I'm in. Keep the car in the highest gear possible for the speed you're traveling. Going to high revs also kills mpg. Jack Rabbit starts are fuel killers.
Rams
[This message has been edited by blackrams (edited 03-19-2021).]
My Uplander van has the Flex-Fuel 3900....I was getting 29 mpg highway back in 2009-11 with it, but since we have changed to 10% ethanol it is down to 26-27 mpg.
My 1999 F-bird Formula had only 2000 miles on it when I had to go to a Hazmat Transportation class for the CG in Oklahoma city....I got into town and calculated my MPG (I had been doing 70-75 the whole way with the AC on)......30.4 MPG! That car was so aerodynamic it probably would have to be doing 90+ before any real detriment to efficiency.
By the way, that was right after the big twister hit the city...I was driving on I40 near the city and saw one of those corrugated farm silo things laying in the median of a clover-leaf......Saw it, then saw NO TRACKS for it to have "Rolled off of a truck" and realized it had.....Fallen straight out of the sky! (I didn't piss myself but it was close! (And I thought EQs were scary!)
