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2.8/3.1 headers Question


89oldscutlass

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I was just wondering I seen where someone had asked about headers for our 2.8s and 3.1s. I dont think you can buy aftermarket ones but couldnt we use the factory headers off a 84-88 fiero 2.8 there about the same block other then the intake? I had a 86 with a 2.8 and all of them came with factory headers on the v6s.

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Fiero headers wouldn't work for N/A 2.8/3.1 engines. You have to remember that the Fiero was a RWD car. The headers would exit out the side where the TB is. Not a good place. :wink: Also, the block makes no difference. It's the HEADS that matter when you're talking about exhaust headers. But, the bolt holes don't line up quite right. The Iron heads have just a little different spacing than the GenII/GenIII aluminum heads.

 

One last note...the stock Fiero "headers" are extremely hard to find! They had a tendency of cracking :oops:

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Getting new headers for a fiero are no problem I wouldnt be putting used ones on it. The headers exhaust run straight down so they wouldnt be probs with the TB now as far as them bolting on our heads that might be the prob without using fiero heads I dunno which heads put out more hp. Most of our hp improvement over the fiero was the better multiport FI system.

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Fiero headers wouldn't work for N/A 2.8/3.1 engines. You have to remember that the Fiero was a RWD car. The headers would exit out the side where the TB is. Not a good place. :wink: Also, the block makes no difference. It's the HEADS that matter when you're talking about exhaust headers. But, the bolt holes don't line up quite right. The Iron heads have just a little different spacing than the GenII/GenIII aluminum heads.

 

One last note...the stock Fiero "headers" are extremely hard to find! They had a tendency of cracking :oops:

 

odd, wouldn't a transverse mounted engine have almost the same exhaust setup? only shorter, right? since the Fiero was also rear engine...

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odd, wouldn't a transverse mounted engine have almost the same exhaust setup? only shorter, right? since the Fiero was also rear engine...

 

Not really. If you think about it....the fiero exhaust comes right off the manifold-like "headers" and right into a Y-pipe. Now...if the headers from a fiero would be mounted on a transverse engine, they would still exit out the TB side like on the fiero, ONLY..the side is not where you want the exhaust to go. The front "header" would be fine, as it needs to crossover to the rear anyway. BUT, the rear is exiting out the side..instead of the BACK..where it needs to go. I'm not sure how much you've looked at the engine bay of a W-body, but there wouldn't be much room to route a pipe coming off the end of this rear "header", let alone a collector. You would to have a pipe in there that bent right around and went down and back, but if you do that, you just shot your flow to shit..defeating the purpose of the headers. You could in theory put a crossover between the front and rear header and then modify the rear header so that it exits out the rear, but I'm not sure how much more flow that would net you, when compared to porting manifolds.

 

And the 2.8 Iron heads aren't the greatest. The fiero headers need little modification to fit Gen II heads (nothing a drill bit won't fix! :twisted: ), but I don't see it being feasible on a N/A car. They are however appealing for a turbo setup, where the exhuast must exit out the side. :wink: :twisted:

 

EDIT

 

I'll use this pic as an example. These are KFG fiero headers. The top would be the header towards the back of the car. The bottom would be towards the front. Do you see how it's not exiting in the correct spot? And how that could be a problem? Also, the exhaust on a Fiero does go down, but it does not have the tranny in the way when it does so. It goes down, and straight back into a muffler.

 

KFG_Headers_copy2.jpg

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These are KFG fiero headers.

 

KFG_Headers_copy2.jpg

 

Just out of curiosity, how are these even headers?

I thought the definition of a header is equal length tubing to the collector. The KFG "headers" definitely don't fit that description. It just looks like a tubular conventional exhaust manifold to me...

 

Do I have the definition of headers mixed up with something else?

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That's what the fiero guys call headers..I guess. The stock "headers" that people say came on the 2.8s from the factory looked VERY similar, only they had a tendency to crack. I don't make up the names..I'm just stating the information. Yes..they do make equal length long and short tube headers for the fiero....but they defineately would not work on a transverse engine. The designs just aren't right.

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Well, I did some research and discovered there are unequal length headers too, so they don't necessarily have equal-length tubes. However, all real headers that I've seen still consist of separate tubes to the collector.

 

The Fiero "headers" are really stretching the definition!

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I thought the problem with the cracked headers was on the 4 banger. My 1986 fiero had 210k on it and the headers where fine on it. My sister has a 87 fiero gt fastback and it has 230k on it and hasnt had a problem with her factory headers. You guys are right about them not bolting up to our heads. Im going to go take a closer look at my sisters fiero exhaust system this weekend to see if there is anyway to make them fit on our cars. On the flip side I dunno if all the work would be worth only 6 to 8 hp not including the price of new headers. :(

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Well, I did some research and discovered there are unequal length headers too, so they don't necessarily have equal-length tubes. However, all real headers that I've seen still consist of separate tubes to the collector.

 

Hmmm..interesting info. :D

 

And I didn't say they WOULDN'T bolt up...they just need some modification :wink: I can find the specifics. It was in a thread on 60* v6, and I have the link somwhere. I'll have to look for it.

 

EDIT:

 

Quote from 60* forums

 

To modify the iron head headers to fit, you must relocate the bolt holes about 3/16". This requires access to a welder. I did this by drilling the original bolt holes out to 3/8". I then cut pieces of 3/8" mild steel round stock to the same length as the thickness of the flanges. After chamfering the edges, I then welded them into the holes. After 20 minutes with the grinder, you would never know there had been holes there. I then marked and drilled the new holes for the Gen3 heads. The entrance to the header required minor grinding to clear the corners of the D-shaped ports.

 

You can do this without the welding by grinding the holes into an oval shape to work for either ones, but this is not easy to do. You could also use a hacksaw to cut the holes into slots, but this would make it very hard to line then up when you tighten the bolts.

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would 3100/3400 headers fit / make a difference on the 2.8/3.1 engine?

 

The exhaust ports on the 2.8/3.1L heads are circular in shape and the 3100/3400 are D-shaped. So they wont really work

 

Robby

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would 3100/3400 headers fit / make a difference on the 2.8/3.1 engine?

 

The exhaust ports on the 2.8/3.1L heads are circular in shape and the 3100/3400 are D-shaped. So they wont really work

 

Robby

 

True..but as long as you would be going through the hassle of adding headers, you could always add GenIII heads too! :D :lol:

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would 3100/3400 headers fit / make a difference on the 2.8/3.1 engine?

 

The exhaust ports on the 2.8/3.1L heads are circular in shape and the 3100/3400 are D-shaped. So they wont really work

 

Robby

 

True..but as long as you would be going through the hassle of adding headers, you could always add GenIII heads too! :D :lol:

 

Well yeah, that would be the smart thing to do.............. :P

 

Robby

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