quote Originally posted by Brian27: Yellow-88, I'd be interseted in a TRUE tuned exhaust system for the Fiero. I am redoing my intake system this spring and hope to do the exhaust after that. I've been leaning towards the WCF headers & 2.5" system.

Hello.

WCF headers are one of the best available, but still fall far short of true tuned headers. The 2.8 is a small engine, and 2.5 finale pipe may actually be too big, causing loss of velocity. The best that I can tell from the math is 1.25 x 18 primary, into 1.75 x 24 secondary, into 2.25 collector. After that it's a personal sound choice.

Write to me directly for more details.

quote Originally posted by crzyone: I'm thinking of building some good flowing less restrictive non tuned headers. If I do decide to put my turbo on this motor, tuned headers won't do me much good. A nice pair of shorty headers like the 3800sc ones should be perfect. Anything would be better than the heavy restrictive stock manifolds.

what about porting the stock manifolds - both the 2.8 and 3800 have shown exquivalent results to headers simply by porting the stock manifolds. its almost free and can't hurt right?

I was also wondering about porting the stock manifolds on the 3.4 DOHC

quote Originally posted by ETC/GT: I was also wondering about porting the stock manifolds on the 3.4 DOHC

Generaly, with modern engine design, I'd be extreamly leary about porting without flowbench data.
Those ports apear to be well designed, and are rather large. Personaly, I wouldn't touch them

Porting 3.4L manifolds does little if anything for performance.

As for the headers, I can say from personal experience with building them that 42" long primaries are way too long. Mine on my Z34 are only 30", but if I was to do it again, I'd use 36" and 34" for a 96-97 engine. For a single size primary, not the dual stage, I'd suggest 1 5/8" pipes. This is perfect, and what I am using on my Z34. Then run dual 2.25" collectors, and collect those into a single 2.5" to run back (the finale pipe I guess). 2.5 is not by any means overkill on a 3.4L DOHC, in fact if I had the money I'd convert mine to a single 3". I really am not a fan of dual staged headers, they increase costs of manufactoring a lot, and do very little for performance. But if I was to do them, I'd use a 6" section of 1 5/8" that transits into a 30" section of slightly larger, maybe 1 3/4".

No engine will show results like headers with ported manifolds. There simply is no way. I do not consider Hedman and WCF headers to truly be headers, they are more manifold replacements in my opinion. The primaries are any random length, whatever makes production costs the least, and the collector, if you can call it one, is simply done with a hack saw and welder. Even without going tuned, there is no replacement for true tuned equal length headers. And they aren't that hard to fit, and true header manufactorer will make them fit. I don't know how familiar you all are with the FWD 3.4L W-bodies, but cramming true equal length headers in one of those is quite a challenge. I had to cut apart my test set and totally redesign them twice in order to get them working correctly. I'm hoping my Fiero, with no trunk, will have enough room for me to get a true dual tuned set of headers and exhaust, and a working X pipe along with dual mufflers.

Turbo headers are very different. Shorty style for those is a good thing, get the exhaust gases to the turbo as quickly and efficiently as possible. I'd still use a 1 5/8" primary though.

quote Originally posted by AaronZ34: Porting 3.4L manifolds does little if anything for performance. As for the headers, I can say from personal experience with building them that 42" long primaries are way too long. Mine on my Z34 are only 30", but if I was to do it again, I'd use 36" and 34" for a 96-97 engine. For a single size primary, not the dual stage, I'd suggest 1 5/8" pipes. This is perfect, and what I am using on my Z34. Then run dual 2.25" collectors, and collect those into a single 2.5" to run back (the finale pipe I guess). 2.5 is not by any means overkill on a 3.4L DOHC, in fact if I had the money I'd convert mine to a single 3". I really am not a fan of dual staged headers, they increase costs of manufactoring a lot, and do very little for performance. But if I was to do them, I'd use a 6" section of 1 5/8" that transits into a 30" section of slightly larger, maybe 1 3/4". No engine will show results like headers with ported manifolds. There simply is no way. I do not consider Hedman and WCF headers to truly be headers, they are more manifold replacements in my opinion. The primaries are any random length, whatever makes production costs the least, and the collector, if you can call it one, is simply done with a hack saw and welder. Even without going tuned, there is no replacement for true tuned equal length headers. And they aren't that hard to fit, and true header manufactorer will make them fit. I don't know how familiar you all are with the FWD 3.4L W-bodies, but cramming true equal length headers in one of those is quite a challenge. I had to cut apart my test set and totally redesign them twice in order to get them working correctly. I'm hoping my Fiero, with no trunk, will have enough room for me to get a true dual tuned set of headers and exhaust, and a working X pipe along with dual mufflers. Turbo headers are very different. Shorty style for those is a good thing, get the exhaust gases to the turbo as quickly and efficiently as possible. I'd still use a 1 5/8" primary though.

I agree about manifold porting. They don’t work anyway, so whatever you do to them is for your entertainment. Go ahead, do it.

Yes…. 42” primaries are to long for just about anything. Your single stage 1 5/8” x 30” primaries seems right for a 3.4 running high in the RPM range.

Dual collectors, 1, 3, 5 and 2, 4, 6, feeding a single pipe on a 60 deg V6 is a dual stage header, is it not? The collectors are the second stage.

A 90 deg. V8 is a different animal.

In my opinion, in the 60 deg V6 Fiero, the 2 stage, or Tri-Y is much more doable, because as you say, snaking all that tube is not at all easy. I agree that there is no differance in perfomance between TRUE dual, and TRUE single stage headers.

The best I can tell, is that a 3” final pipe would be too big until about 7000 rpm. It would be interesting to see dyno results using different size final pipes. At 200 plus HP, it would be hard to really “feel” a difference of even 5%. With any system as nice as yours, a twin cam Chevy would scream.

I agree 100% about the header products out there.
And yes, a turbo has a whole different set of parameters.

With your experience, I’d like to talk with you more about this subject.

Well I just spoke to the guy going to make my headers. He is doing my complete exhaust including headers mandrell bent pipe and mufflers for $475.00. I believe thats a reasonable price. Im doing 1 5/8 primaries into a 2.5 inch collector. I will see about him making more than one set of headers and try to sell them on here IF he wants to. I do know his work is great and he has made many headers before and is the best performance exhaust shop around my area. He is a friend of mine and has done all of my exhaust work for the last 7 years and Im always happy with the results

Porting the original manifolds isn't really a viable option. If you look at a front manifold it bends like a snake. Would make it pretty impossible to get in there and remove material. It would be easy to make a nice small set of headers. Its hard to imagine how a tuned 36" set of headers would look like in a fiero

With a turbo the header design doesn't matter nearly as much. As long as there is little restriction as possible.

Would headers for a 3.4 TDC work on a pushrod 2.8/3.1/3.4?

I could make them work, but gererally, no. First of all you'd want small primaries, and I'd have to change the flanges. And since the pushrod motors have offset exhaust ports, like o..o.....o, it'd totally change the way the pipes are routed.

475 for a set is quite a deal, are they going to be equal length or not? As for the collectors, I'd highly suggest sticking with dual 2.25" and then going into a single 2.5", you will notice the maximum gains this way. And with an exhaust, that price is great.

As for the headers, they will be pretty weird looking, but they will fit and will function like none other out there if I ever get around to building them...

------------------
1992 Lumina Z34 5-speed For Sale, modified(high 13s), or stock
14.78 @ 92.68
1992 Lumina Z34 5-speed
Stock, new crate engine and trannsmission
3.4L TDC V6, getting built to about 430hp at 8000rpm for a 88GT

well, I used the Spintek muffler that WCf sells, and it sounds ok. It is loud, probably mostly because my exhaust is so short. It does tend to rasp in the mid range. I would have added a resonator, but the exhaust is coming off sonn anyways.

I think the best setup was on Eric's car. HIs car had the smooth exotic sound I was looking for. Kinda like the Ferarri on Bad Boys 2. I heard on the post that Crzyone did when he was asking if his car sounded cammy.

Anyhow I have pics of my exhaust before I finished it up with the tailpipes on my page.

quote Originally posted by crzyone: Porting the original manifolds isn't really a viable option. If you look at a front manifold it bends like a snake. Would make it pretty impossible to get in there and remove material. It would be easy to make a nice small set of headers. Its hard to imagine how a tuned 36" set of headers would look like in a fiero With a turbo the header design doesn't matter nearly as much. As long as there is little restriction as possible.

thats why i'm not worrying about it right now since i plan to turbo later - my chip is already burned to take boost - just have to plumb in the turbo when i'm ready