Alright, as many of you know, I was the recipient of the first true Fiero Overhaulin'.(I say "true" overhaul, because, while the Tyler Project was an overhaul, Tyler was very much involved in it, during planning and the build with his input and advice, while I was completely out in the cold not knowing any of this was happening.) Part of the overhaul included a new engine. Now, all I'm really sure of is that it's a 2.5L Iron Duke, I've been told that it's hopped up and modified, and after driving it I can believe it. From what I've been told, and as was posted in the original thread, it's bored .030 over, one piece oil rings, comp cam, roller rockers and lifters, decked the head, higher compression pistons, drilled out oil galleys for better flow to the had and also has a one of a kind hand built header.

Now, after putting almost 800 miles on it since I took delivery of it 2 weeks ago tomorrow, and one of the major bugs was fixed today, I figured now would be a good time to start a thread about it and write a review. (this review is being typed out the way it enters my head, so it'll probably wind up incredibly disjointed and moderately confusing.)

First off, I'm not sure that it's fair to compare it to a two hundred some-odd thousand mile, 25 year old, worn out engine. Like I said, we solved a major problem with the engine today, as it wasn't wanting to run right and was dogging under 3k RPMs, then screaming out when the timing advanced. We(Myself and Fieroguy123) replaced 2 temp sensors, adjusted the timing and replaced the spark plugs over the last week and a half to no avail . Today, we were going to replace the ICM and when I pulled one of the plugs off the ICM, I noticed that one of the wires to the ICM was broken. After repairing the broken wire, it fired up and ran like a fracking champ!

On my way home from Fieroguy123's house today (about 56 mostly interstate highway miles), I ran it through some mild testing and came away very impressed. One of the first things I really noticed while cruising at 60-65mph, I don't have to downshift to pass. It cruises at 60mph at around 2,400RPMs and when you give it the gas, it picks up and goes. I've also noticed that it can cruise at just under 1,800-ish RPMs without bogging(I wouldn't recommend it, but it'll do it), it's happier at around 2,000-2,300, but it'll cruise at 1,800. During acceleration, I've noticed that power starts to drop off at around 3,700RPMs and completely bottoms out at around 4,200RPMs. Whether that's because the engine still needs a bit of breaking in, or if it's a permanent side effect of the mods done, I don't know at this point.

1st and 2nd gears both go by so quick there's nothing really to say about engine performance. 3rd gear hangs out for a touch longer and it's still pulling incredibly hard. 4th gear is around for longer still and the engine is still pulling fairly hard. I haven't reached the top of 5th yet, but between 2,800 and 3,400 RPMs, this engine pulls 5th gear to the point of almost feeling like it's still in 4th. I'm confident this engine, when dialed in properly, could outpull a 2.8 and maybe even give an unmodded 3.1 a run for it's money. I know it feels a lot more energetic than the 3100/auto in my g/f's '98 Malibu.

As far as fuel economy goes, I was told they were aiming for 40+ mpg when they installed this motor, and I'm going to keep track over the next month or so and see where it sits. Then I'll probably start looking for ways to make my fuel economy even better.

I don't know how much money was spent on this engine, and I'm sure that I don't want to know, but, knowing what I know now, if I were the one spending the money, I would probably go this route. For a daily driver that's never going to see a track, built for reliability and economy, I think it's money VERY well spent. It's a perfect drop in, no special wiring and no special plumbing for anything. It was also a 0-mile engine when modified and 0-miles were on it when it was installed in my car, you don't get much better than that, even when stock.

[This message has been edited by Rallaster (edited 06-18-2011).]

Sounds sick, Hope you enjoy the Fiero to it's fullest... After break-in of course.

I drove the sh#t out of Rallasters car today and I have to agree. She's pretty peppy.

quote Originally posted by fieroguy123: I drove the sh#t out of Rallasters car today and I have to agree. She's pretty peppy.

Bout time... hope to get a chance to try it the next time i come out. Just glad your happy with it. WINNING!

I'm really glad your happy with the engine. I'm the one who built it. I had an 84 and an 85 Fiero. This engine was going to go into the 84. Sold both cars and never had a chance to see how it would run for me. Sounds like your happy with it's proformance. Enjoy it.

Rallaster, did I read else where you were going to try to head to Frazee the end of July or is that just wishful thinking on my part? I certainly hope so. I certainly like to meet you and the others involved in your overhaul, not to mention seeing the cars as well. That would be a great way to calculate MPG, wouldn't it?

I gotta see any and all modded 2.5s at frazee, the more the better, mine will be the smokey and knocky panda colored notch.

quote Originally posted by stevelima: I'm really glad your happy with the engine. I'm the one who built it. I had an 84 and an 85 Fiero. This engine was going to go into the 84. Sold both cars and never had a chance to see how it would run for me. Sounds like your happy with it's proformance. Enjoy it.

I'm loving the engine! Had a kink in the very beginning with a wire to the ICM being broken, but that was the only engine problems we've had to work out. It sounds mean and it hauls much better than the old duke I had.

Take it to a track day, then you'll really love it! Glad your happy with your Duke!

My route to Frazee takes me to Chicago and then a stop in Madison, WI. From there I plan to head for the Twin Cities for the Friday convoy to Frazee. So hopefully we'll meet each other on the way or in Frazee. Otherwise I'll be forced to wait until 2013 and the 30th Anniversary, to be held in Indianapolis. In the mean time, I'll keep my fingers crossed that things will work out for you. I'm sure there is a beer (or insert name of your favorite drink here) with your name on it that I'll be more than happy to hand to you.

I also have a rebuilt duke bored .030 over with an MSD coil, and otherwise stock. 2800-3400 rpm range is where it wakes up, and as you found, there's no point pushing it past 4200 or so. SO much better than the old tired out engine, huh?

Well, the modded Duke has really reared it's B-E-A-UUUUUUtiful head here in the last day or so. Because of a lack of gas monies and other restricting issues, I haven't been able to drive it as much as I would like and haven't been able to do a real mileage run.. that was until yesterday. Yesterday, I started my new job on the northside of Indianapolis. For those that don't know, I live south of Indy in Martinsville. It's 48 miles from my driveway to the parking lot at work, making for a 96 mile round trip and it's a fairly even mix of city and highway miles, so I get a good variety of stop/go and cruising. In the 96 mile round trip to and from work yesterday, the gas gauge moved a total less than 1/4 tank. I'm estimating it used around 2 1/4 gallons since a full 1/4 tank is about 2 1/2 gallons. If my estimations and subsequent math is correct, I'm staring down the barrel of 45-46 MPG. And that's on a jank distributor with a jank pick-up coil/ICM. (the distributor on this engine is the old one off the original engine.) I have a new Cardone distributor that comes with a new pick-up coil, ICM, dizzy and cap on order from Rockauto that should be arriving tomorrow(and will be the final piece(s) to make the entire ignition system new[less than 1k miles]), so that problem will be out of the way and I'll be able to really push the economy to the max. I expect the fuel economy to come very close to, if not surpass, 50 MPG, but we'll see.

I would fill up at the 200 mile point just to double check your expectations. Hope the gauge isn't lying to you.

Is their a list of parts used for this? I am very interested in doing this to my duke.

quote Originally posted by 2farnorth: I would fill up at the 200 mile point just to double check your expectations. Hope the gauge isn't lying to you.

Yeah, I plan on doing that after I get my distributor installed and get it timed right. I think my gauge is accurate, but I don't know, so doing a fill up for confirmation is in the plans.

[This message has been edited by Rallaster (edited 08-31-2011).]

Thanks bud!

Maybe it's the way I drive, but yea I was wondering myself how you got that good of mileage out of the Duke/5-speed combo. I thought what was done to the Duke was for performance purposes only while still getting good gas mileage. But I guess it's a performance increase AND gas mileage increase, what a deal! Then again our Duke/5-speed has 183K miles on it, so who knows. I have gotten 40MPG pure highway with it.

My duke has 257,xxx miles on it and its a ticking time bomb I am sure. I havent a clue what MPG its getting as I have only driven it around my house playing with it. I have yet to "Drive" it. If I have to do motor work (which will be imminent soon), I would love to not have to do a swap but still get enough HP out of it to be pleasurable to drive etc.

It sounds like it has a different cam in it. It sounds like it has cam designed for low end torque. Which is good. I sold BIG trucks for about 9 years. Torque is what you want. I have wondered what it would be like to have a power band from 2500 to 4500. Your mileage is great. The best I have gotten with 88 2.5, 5 speed is 38.5.

How many mpgs does it actually get, have you filled up yet?

quote Originally posted by 2.5: How many mpgs does it actually get, have you filled up yet?

This is the best way to find true mpg. GM's system works off of the fuel level control in the tank. I have noticed that they are close but not 100%.

Steve W.
NE Grand Rapids, MI
88 Coupe

quote Originally posted by 2.5: How many mpgs does it actually get, have you filled up yet?

I have not had a chance to fill 'er up yet. On my way home from work Tuesday the front shocks blew out(they weren't replaced with the rebuild and I don't have a clue how old they are) and the air dam drug the ground and got half ripped off. GRRRRR. It's going to be tomorrow or Sunday before I'm going to be able to get the shocks replaced and the air dam reattached, so it's going to be Monday or Tuesday before I'm going to be able to get an accurate reading on the mileage.

Got the new distributor installed and timed, and oh boy, does it run. As far as power, I'd EASILY put it up against a stock 2.8 and give a stock 3.1 a very serious run for it's money. A modded 3.1 and stock 3.4 would probably win, but I think it would be close. A modded 3.4 probably wouldn't even have much of a challenge, but it sure would be fun.

Serious mileage test starting Tuesday with results to be posted on Friday evening, stay tuned.

I'm just glad to hear it's still running and in better shape then it was

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"Remember: amateurs built the ark ....
professionals built the Titanic."

quote timgray Because that is all a corvette is good for, parts for the fiero..

Part of the Rallaster "Overhaulin" project. 6/4/2011
https://www.fiero.nl/forum/Forum1/HTML/085568.html

..I had an 88 duke that was stock,, the MPG will be 38 to 40 mpg at 65.
.. the stock 87/88 duke is a solid performer it has all the pep you need around town,, you will not stay with hi performance car,s but it is fun to drive ,One day we will have $5.00 a gallon gas or higher & the duke will look better
there is no reason to install the ecotech, the duke does the job
for better Gas milage & performance install the later model duke head on the 87/88 duke
for the more experienced install a 1992 duke with the 92 ecm you can equal the mpg of a 95 honda civic or toyota tercel with better pulling power
..also do not forget the edelbrock elite air cleaner can be adapted to the Duke TBI,, giving the duke engine compartment that certain Panache, a jeanne say squat..not a bolt on but easy adapt.
..the late model duke engine with minor modifications, hooked up to the 4 speed automatic can give satisfactory performance with excellent MPG..
..The duke does not have the sturdy engine block for hi RPMs but a reall good street machine has been built by many Fiero enthusiast.
there are a lot of super duty parts that can work on the duke,performance is not cheap

[This message has been edited by uhlanstan (edited 09-05-2011).]

quote Originally posted by Rallaster: Got the new distributor installed and timed, and oh boy, does it run. As far as power, I'd EASILY put it up against a stock 2.8 and give a stock 3.1 a very serious run for it's money. A modded 3.1 and stock 3.4 would probably win, but I think it would be close. A modded 3.4 probably wouldn't even have much of a challenge, but it sure would be fun. Serious mileage test starting Tuesday with results to be posted on Friday evening, stay tuned.

Sorry to hear about the shocks and subsequent damage.
Thats pretty quick, you shoudl get some 0-60 times

quote Originally posted by GADJet: My duke has 257,xxx miles on it and its a ticking time bomb I am sure. I havent a clue what MPG its getting as I have only driven it around my house playing with it. I have yet to "Drive" it. If I have to do motor work (which will be imminent soon), I would love to not have to do a swap but still get enough HP out of it to be pleasurable to drive etc.

It's NOT a race car by any stretch, but it is definitely a step up from the old worn out Duke I did have. (I think the term is "spirited" daily driver.. )

Well, week 1 of testing is behind me by a few days and so far, fuel economy is looking phenomenal. I'll post specific numbers tomorrow or Thurs., but I'm very impressed to say the least.

On a side note, 85MPH does not a 50MPG car make... I filled up this morning before going to work and the needle on the fuel gauge was on the top side of the full mark, it was still touching the mark but just barely. 51 miles to work at 55-60MPH and the fuel needle was covering the bottom half of the full mark with the top half exposed. Very good fuel mileage. On my way home... :evil grin: I took a longer route and I wound up on the interstate at the tail end of rush hour with the highway mostly empty and those that were on it were travelling at a high rate of speed. I accelerated to a comfortable speed and was getting passed by everyone and passing noone. I looked down and was doing 80-85 MPH. At 80MPH the tach reads ~3300RPMs in 5th gear and I can crack the throttle bit more and still feel it pull me into the seat as it ever so smoothly surges forward(such an awesome feeling. ) I ran like that most of the, now 75 mile, trip home. I pull in my driveway and look at the fuel gauge and it's reading barely more than half a tank.. I think it's the last of the commutes that exceed 65-ish MPH.

Given the proper gearing, I have no doubts this engine could power it's way to 160+, whereas the Duke that was replaced was doing good to sustain 80MPH with a tail wind. For being "just" a 2.5L Iron Duke, I am extremely happy with where the power band is and the incredible improvement in power from the mods done. It can pull a hill in top gear without the need to downshift, and can even accelerate up the same hill without downshifting. If I'm cruising at 2,300-ish RPMs, downshifting for almost any reason is unnecessary. The power band is greatly improved from the stock Duke to the modified Duke. It hits power at around 2,400RPMs and starts to drop off around 3,500RPMs and falls off a cliff at around 4,200. If there was a bolt on that could extend the top end of the power band by 3-400 RPMs, I think it would be a fantastic investment as long as it leaves the bottom end of the band alone. I think that's the only thing I would change about this engine if I could. For maximum power in all gears, I have to shift out before 3,600-3,800 and I'd like to be able to extend it out to 4k sometimes for that extra time in gear while merging on the highway. (I'm not complaining by any stretch, just simple observations based on my driving technique)

That's pretty awesome. I agree, the Duke that I'm used to right now has a bit of trouble getting to 80-85 MPH. If I need to pass someone I usually need to downshift depending on the situation.

Wow that is interesting. I would love to know what type of cam is in the engine. My power band is different. I think I a P.O. had a new service engine installed as it looks to good and is quite for an original duke. I bought the car with 86k and it now has 170k. I have notice when under full acceleration that my engine seems to pull strong(if a stock duke could do that LOL) up to and past 5000 rpm's.

Thanks for the info. I'll look up for the build specs.

quote Originally posted by solotwo: Wow that is interesting. I would love to know what type of cam is in the engine. My power band is different. I think I a P.O. had a new service engine installed as it looks to good and is quite for an original duke. I bought the car with 86k and it now has 170k. I have notice when under full acceleration that my engine seems to pull strong(if a stock duke could do that LOL) up to and past 5000 rpm's. Thanks for the info. I'll look up for the build specs.

I don't push past 4,500RPMs as it starts to sound ragged at around 4,600-4,700. 99% of the time I'm shifting at around 3,300-3,500 for fuel economy, and that puts the bottom of the gears around 2,200-2,500 and it feels like that range doesn't really benefit from full throttle application. When under a load at anything less than 3k, more than 50-75% of full throttle feels wasted and doesn't seem to provide any more power to the wheels. Don't get me wrong, it has considerable power at that range and throttle application, it just doesn't feel like it's producing any more power with the throttle being any further open.

[This message has been edited by Rallaster (edited 09-14-2011).]

Yes I noticed that also. under 3k no guts. I do lite throttle to get some mileage.

quote Originally posted by solotwo: Yes I noticed that also. under 3k no guts. I do lite throttle to get some mileage.

At 2.3-3K if I'm not careful it can give you whiplash. It's not lacking in guts at that range, it just doesn't get anymore guts with more throttle. I'd be interested to see what it has as far as torque numbers go. If I'm at the bottom of 3rd, it really feels good, not lacking in power and if you give it the throttle, it just flat get's with it. For example, I was in a school zone cruising in 3rd gear at 2k-ish RPMs and at the end of the zone I crammed the throttle to get back up to speed and the nose of the car rose 4 inches and stayed there until I let off the throttle at 3,500.

3k is where I was told the timing advance hits, so that could be part of the reason 3k is your sweet spot. The ignition timing advance combined with your cam setup could possibly kill your bottom end.

[This message has been edited by Rallaster (edited 09-14-2011).]

Wow, my duke must be in pretty bad shape then. It can get you around but...yea. Anything past 4k sounds like it's going to literally blow up at any second. If I'm in 3rd at 2k RPM, and I punch it...not much happens. Lol. Then again I could be biased from driving a V8 Fiero everyday.

[This message has been edited by mattwa (edited 09-14-2011).]

quote Originally posted by mattwa: Wow, my duke must be in pretty bad shape then. It can get you around but...yea. Anything past 4k sounds like it's going to literally blow up at any second. If I'm in 3rd at 2k RPM, and I punch it...not much happens. Lol. Then again I could be biased from driving a V8 Fiero everyday.

My old Duke was that way. It didn't have the power to even get out of its own way... ever. The Duke that was donated for the build is a beast. If it was my money going into it, I would have done the same thing. The Tech4 is what came in the car, and although it's highly modified, it's what's in the car now and like I posted earlier, I'd easily put it up against a stock 2.8 or 3.1.

About 6 or 7 years ago, Neil & Dawn Kline (racincouple) of PA., built a modified Duke engine that IIRC used SBC 10.5:1 compression pistons, a hot cam, ported heads, headers and a nonrestrictive exhaust system. I didn't drive their Fiero but Neil always claimed that the car was competitive with a 2.8L Fiero. Shortly after this Neils migraine headaches got worse and he could no longer work on cars. He sold the car at a great price 2 years ago and I don't know who owns it now. I would guess that the engine made 150-160 horsepower so it was built at a power level where it stayed together. For cruising, hitting the road, and commuting you can keep up with traffic. . As long as you don't go crazy with mods, boosting, or high revs, the Duke is a proven reliable powerplant that will get you great highway mileage and in your case a bit of pep to boot.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, 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 "