Okay, So im well aware that its a fairly lost cause to do any major performance modifacation to the Iron Duke, but seeing as I'm stuck with one i searched around. Turns out the iron duke was used in Jeeps for some time, and headers were designed for it. I was wondering if anybody has tried to use these headers. <Headers Or, if anybody has specuation to if they'd work.
I have an old performance header from 3 years ago that I had on my Duke. I brought it from the fierostore for $250. I don't believe they make it anymore. If your interested I will sell it to you for $100 plus the shiiping. Its was only used for 6 months then taken off for the Turbo Duke I was building. I think some of the powder coating has come off but still good. It will make a slight diffrence not much though. I will try to get some pics for you today when I get home.
-Frank 86 SE 2.8 Modified 84 Turbo Duke
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03:59 PM
patch Member
Posts: 210 From: Santaquin,UT, USA Registered: Jul 2006
I too have a Fiero store header on my duke. Bolted up nice and looks pretty, but I don't think that it made much of a difference. The only reason I bought it was that I got it really cheap on ebay. It might make a bigger difference on a higher hp duke though.
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05:49 PM
82-T/A [At Work] Member
Posts: 25071 From: Florida USA Registered: Aug 2002
Hooker Headers sold a performance header for the 84 Fiero (works with other years as well). It was a really nice piece. I remember that when I first got into this hobby 10 years ago, you could STILL buy it both from them, and the Fiero Store. I still have the Fiero store catalog from 1997, and it shows it in there. It was something like $219 bucks. It included the header, as well as a complete header pipe (the piece that goes from the header, to the drivers side, does a 180, and heads back around to the cat. If ANYONE runs into one of those on eBay, SNAP IT UP!!!
They stopped making them, but it was THE best bang for the buck for the Iron Duke.
That, and the Holley TBI unit when used with the Holley Intake. Holley produced both an intake, AND a TBI unit for the Iron Duke as well. They had already stopped making the intake manifold by the time I got into Fieros, but I did manage to get enough money in my earlier years to be able to buy a Holley TBI unit... glad I did... they don't make those anymore too.
When I see speciality items for cars I own, and I know that one day I'd LOVE to have them... I just bite the bullet and get it. I know that things simply just get discontinued far too often, and sometimes you just need to go for broke.
Thats my engine. That header is well built. I paid extra for the ceramic metallic coating and it still looks nice. Im wondering if hooker would still build it for you. You could try to get someone at JEGs to special order it for you? BTW this engine has Crane roller rockers, a mild Amotion roller cam, and a Holly big bore tbi. It was ported, indexed, and balanced, and is producing somewhere about 120/130 HP with stock electronics.
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05:44 PM
Jan 26th, 2007
AquaHusky Member
Posts: 1234 From: Sedalia, Mo Registered: Dec 2006
Thats my engine. That header is well built. I paid extra for the ceramic metallic coating and it still looks nice. Im wondering if hooker would still build it for you. You could try to get someone at JEGs to special order it for you? BTW this engine has Crane roller rockers, a mild Amotion roller cam, and a Holly big bore tbi. It was ported, indexed, and balanced, and is producing somewhere about 120/130 HP with stock electronics.
Dude, that's yours? I have that page bookmarked because when I had my 85, I was going to do what you did with mine. That's a very nice looking engine. I especially liked the header, really clean looking. Oh, I also stumbled upon this http://suzukird1.netfirms.c...f4a197c9087db70a8201 Now, if they make this, there has to be headers for the Duke someplace as well.
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09:39 AM
Jan 27th, 2007
fst4rsc Member
Posts: 98 From: Farmington, NM Registered: Oct 2003
Hey fst4rsc, I too have your site bookmarked. Excellent pics and info! I'd like your opion on the performance of your build. How much better is it than the stocker? Does it rpm better/higher? Any dyno #s or 1/4 mile times?
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05:06 PM
Jan 30th, 2007
fst4rsc Member
Posts: 98 From: Farmington, NM Registered: Oct 2003
My 0-60 times range from 12 to 10 seconds (ok, quit laughing! yes, its slow!). I keep the revs below appx 5k rpm. The fiero weighs: 1176 kg (2590 lb) to 1265 kg (2790 lb)
Choosing the lighter weight makes the HP calculation more conservative.
1176 kg / 11 s / .9 = 118.8 hp
12 s = 108.9 hp
10 s = 130.7
The HP calculator site listed a bunch of cars to compare the formula prediction and the rated hp of the cars, and they matched up pretty well. So, unless I have made some silly mistake, it seems to be 120/130 HP. Everything is fine about the engine except, the idle has suffered a little. I think, or I wonder if, I could get closer to the targeted 140 mark with custom electronics and tuning.
OH, I just called that guy, and it turns out he makes them to go *up* out the hood. He says he doesn't have an engine to figure out how to get them to down, for the Fiero.
So, does anyone in the Ohio area have a Fiero that you could take over to him, so that he can spec out the fiero based duke header? Here is his contact info:
DEC Headers 13491 St. Route 122 Somerville, Ohio 45064 Phone 513-267-1615 e-mail: info@decheaders.com
Edited: Fixed the link.
[This message has been edited by ScotMac (edited 10-01-2007).]
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03:48 PM
frankenfiero1 Member
Posts: 441 From: maryville TN USA Registered: Oct 2006
Yes, you really do need to update that site! I have quoted it here many times and would like to see more of it. I am a "Duke Head" and will not consider ANYTHING else for my "Baja" fiero. Please update or PM or e-mail me on anything else you might have done...
------------------ carpe diem
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06:43 PM
Dennis LaGrua Member
Posts: 15784 From: Hillsborough, NJ U.S.A. Registered: May 2000
Okay, So im well aware that its a fairly lost cause to do any major performance modifacation to the Iron Duke, but seeing as I'm stuck with one i searched around. Turns out the iron duke was used in Jeeps for some time, and headers were designed for it. I was wondering if anybody has tried to use these headers. <Headers Or, if anybody has specuation to if they'd work.
James
Just be aware that Jeep used two different 4 cylinder engines in the 1980's One was in fact the GM Iron Duke. The other was an American Motors designed 2.5L 4 cylinder engine. My Jeep Comanche pickup has the AMC engine. This is not the same as the Duke engine. The AMC 4 cyl. also makes more horsepower and has a higher 5000 RPM redline. Before you buy any header just make sure that it's for a Jeep with the GM engine, and if its not Fiero specific expect to modify it to fit. As for perfromance modifications, the only guy that I know of that did a performance Duke build that held together was Neil the stickman_2. He spend more time researching the Duke engine than most anyone on this forum and usually has some good info to share.
------------------ 87GT 3.4 Turbo- 0-60 5.2 seconds 2006 3800SC Series III swap in progress Engine Controls, PCM goodies, re-programming & odd electronics stuff " I'M ON THE LOOSE WITHOUT THE JUICE "
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08:13 PM
Oct 2nd, 2007
The_Stickman2 Member
Posts: 1030 From: Lehigh Valley Pa. Registered: Sep 2007
Ok it seems I am only responding to Duke threads. Guess that's all I'm good for . Anyway. If you look at the Jeep header the flange is the same as the Fiero GM Duke. Then take a look at the Hooker Fiero header. Looks like where the Fieros starts to bend down towards the cat is where the collector on the jeep is. Now there was the Headman/JR of which I have two. They tend to crack at the collector. But they are a good header. I also have a Hooker competition header. It is well rusted and one tube is out of the flange but maybe be able to be used as a template.
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01:54 AM
Dennis LaGrua Member
Posts: 15784 From: Hillsborough, NJ U.S.A. Registered: May 2000
Ok it seems I am only responding to Duke threads. Guess that's all I'm good for .
There are still numerous Duke powered Fieros out there and many owners seem to have a real need for info. I try to help out when I can but my expereince with the 4 cyl is in repairs only not mods. What I post is usually based only on general info. You have spent alot of time buying parts, doing research and building Duke engines. If your expertise leans this way I'm sure that there will be many long posts that would welcome your inputs and for those V6 guys like myself, we gather knowledge in case a Duke Fiero comes our way. I almost bought an 88 Coupe a while back and it fell through and would you believe that I was offered a SD4 a few years back and turned it down as I had no room to store it. There was a Fiero kit car shop in my area called Whitehorse that was vacating in a hurry as the building was sold. The owner told me that I could have the SD4 ( it was used) if I just would come to pick it up. Not knowing the value I told him that I needed to pass. I believe that engine was later scrapped. Getting back to headers, the stock Duke manifold already looks like a header design. I wonder if a bit of porting would yield results as on the V6?
------------------ 87GT 3.4 Turbo- 0-60 5.2 seconds 2006 3800SC Series III swap in progress Engine Controls, PCM goodies, re-programming & odd electronics stuff " I'M ON THE LOOSE WITHOUT THE JUICE "
The 88 duke exhaust is a header from the factory, very possible this could be adapted to early models with torch and BFH,, there have got to be many 88 dukes headed to japan and china for a crushing burning vacation to the slant eye smelter ,,save some of the exhaust pipes and give or sell to 84 to 86 duke owners.. people use to beat and heat and weld V 8 chevy manifolds to fit fiero V 6 and duke ,because you could find them used and buy new for $80.00 and stock fiero headers were $350.oo
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04:14 PM
PFF
System Bot
The_Stickman2 Member
Posts: 1030 From: Lehigh Valley Pa. Registered: Sep 2007
There are still numerous Duke powered Fieros out there and many owners seem to have a real need for info. I try to help out when I can but my expereince with the 4 cyl is in repairs only not mods. What I post is usually based only on general info. You have spent alot of time buying parts, doing research and building Duke engines. If your expertise leans this way I'm sure that there will be many long posts that would welcome your inputs and for those V6 guys like myself, we gather knowledge in case a Duke Fiero comes our way. I almost bought an 88 Coupe a while back and it fell through and would you believe that I was offered a SD4 a few years back and turned it down as I had no room to store it. There was a Fiero kit car shop in my area called Whitehorse that was vacating in a hurry as the building was sold. The owner told me that I could have the SD4 ( it was used) if I just would come to pick it up. Not knowing the value I told him that I needed to pass. I believe that engine was later scrapped. Getting back to headers, the stock Duke manifold already looks like a header design. I wonder if a bit of porting would yield results as on the V6?
wow... sounds painful. There is a link to one on ebay on my thread
The loss of one of those engines is painful. Maybe not for me but because it would have been cool to see someone else with one. I have more SD-4 parts athn I know what to do with. Like those main cap studs I listed in the other thread. I had forgotten I even had them. Only found them and the rockers when I was searching for the reference numbers for your build.
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01:28 AM
fierosound Member
Posts: 15232 From: Calgary, Canada Registered: Nov 1999
Just found this. Anyway, I own an Indy that has the Hooker Super comp headers mounted. They make the duke grumble nicely and I can feel the difference from my last duke, it's not alot, but it's there for sure.
forgot there was a set of duke headers on the mall about 2 weeks ago they were rusty looking, so there is a small chance they may still be there no header for a duke is going to be cheap,because of rarity
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07:50 PM
USFiero Member
Posts: 4877 From: Everywhere and Middle of Nowhere Registered: Mar 2002
Stickman, did you used to post on the Fiero Factory List? Didn't you mention a certain Monza cast iron exhaust manifolds?
Yea that was probably me. God knows I can't remember anything due to my migraines. Anyway there are two cast iron exhaust manifolds you can get.. The one off the Monza, which has a square flange at the bottom where a 2 pipe down tube bolts to which goes back to a single pipe. not much sense to it. But if you could make a new down tube of a bigger diameter to bolt to that flange. My wife's car uses a cast iron manifold from a Citation or Celebrity. Can't remember which. Think it was the celebrity. They will NEVER crack. Actually I am surprised none of the V-6 guys use the cast iron manifolds off the Lumina/transport vans.
Originally posted by The_Stickman2: Actually I am surprised none of the V-6 guys use the cast iron manifolds off the Lumina/transport vans.
I think it's because the geometry is off where the exhaust exits. Would require some tweaking to get the Y pipe to hook up. For a custom turbo setup though it's very much a player.
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11:35 AM
82-T/A [At Work] Member
Posts: 25071 From: Florida USA Registered: Aug 2002
Just to add to what Denis has said, there are a lot of things you can do to the Duke to make it a much more enjoyable car, and won't cost you a whole lot of money.
1 - Make sure the car runs well, is in proper tune, and all maintenance (fuel filter, etc) has been performed. 2 - Replace the dryer hose connector from the air cleaner to the side intake with the newer style one (keep the old one in the attic, basement, or garage). 3 - Switch to semi-synthetic or full synthetic, and use a good air cleaner.
Now as far as modifications go, I'd recommend the following: 1 - Anyone that has a Th-125c should switch to a 4T60 or 440T4, it's a good swap, gives you a better 1st gear, better highway economy, etc. 2 - Anyone that still has an original catalytic converter (the pellet style) should switch to a newer high-flow cat from Rodney or the Fiero Store (or Summit Racing) 3 - A good third option to build more power (easily) is to swap in higher ratio (preferably roller) rocker arms. This will give you the effect of having a hotter cam. 4 - Advance the timing slightly, and use a slightly higher grade of fuel. 5 - Get a Holley TBI unit, or have your stock one bored out. You can then port-match the stock intake.
Now, if you want even more power, you can tear into the motor: 1 - Simple head porting will improve the flow of the motor. I suggest polishing the exhaust valves, and porting the inside of the swirl chambers. Don't port the intake though, for a street car, you'll want the rough edges for better fuel atomization. 2 - You can go with a hotter cam. 3 - You can go with a larger bore piston like a .030 overbore cyl. This will slightly boost compression. 4 - You can also deck the cyl head ever so slightly to boost compression a bit more.
. Anyway. If you look at the Jeep header the flange is the same as the Fiero GM Duke. Then take a look at the Hooker Fiero header. Looks like where the Fieros starts to bend down towards the cat is where the collector on the jeep is. Now there was the Headman/JR of which I have two. They tend to crack at the collector. But they are a good header. I also have a Hooker competition header. It is well rusted and one tube is out of the flange but maybe be able to be used as a template.
