Northstar Fiero swap, 180* headers, not HMT style
04-12-2009, 03:22 PM
#1
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Join Date: Nov 2008
Posts: 166
Northstar Fiero swap, 180* headers, not HMT style
I bought a Maroon 88GT that had a 3.4 DOHC swap in it from a guy in Oklahoma a few years ago. I redid the 3.4 swap, drove it for about a year, then sold it to a good friend who drove it for another year or two. Well it developed a few issues, and he ended up blowing the transmission. I found a Getrag in a junkyard for $60, and we managed to find a good deal on a 275hp N* that had just been rebuilt, but never got installed. The N* and Getrag sat around, but my friend came up with the time and money, so we've begun work on the project. For now, the plan is to leave the N* block stock, run it off a 7730 ECU, and I'll be making some trick headers for it (More details in a bit). I would have liked to get a 300hp variant, but this one came up at the right time, for the right price.
In the past few weeks, we got the transmission clearanced for the N* starter, and bolted that up. Today we finished up the cradle modifications, and it goes down to the powder-coaters on Monday. We are using a modified Fiero front trans bracket, that uses a Dodge P/U engine mount. The stock N* front engine mount is being used. The stock rear Fiero trans mount is being used (Except with a RD poly unit). And the back engine mount is custom, again using a Dodge P/U mount (Can't beat them for $5!). I'll be adding a dogbone up top eventually. We got an aluminum flywheel ordered, I'm not sure how or where, but my friend found it for $400!!! That's the price of a stock Fiero aluminum flywheel! It's in, although I haven't seen it yet. We still need a clutch, going to Clutchnet for that (I've heard enough Spec horror stories that I won't ever go back).
The real pride and joy, the headers. My friend gassed up the welder, and said he'd buy all of the materials if I would build him headers. I started my new job, and am aching to get back into working on projects like this, but am saving my own money for a Jeep SRT8, so I jumped at the opportunity. The headers will be long tube, equal length, 180*. I just can't get over the sound they give, it's biblical. However as we all know, that's not going to be easy. So I'm going to order the piping, and see what I can come up with. Fortunately, with the 6500rpm redline and tame 275 cams, the primary lengths will be long (I'm guessing 36" at least), so I've got plenty of distance to get the collectors placed right to feed from both banks. I actually think I'll have plenty of room for the headers themselves, from the looks of it so far, my 3.4 was far tighter on space constraints. My problem with this is going to be the exhaust. I really want to run dual mufflers and a true dual exhaust, as a single muffler is too loud. However, we also want to keep the trunk, which severely limits exhaust options. Since the swap is still in its initial stages, I've got time to plan. I'm open to ideas.
No pictures yet, I'll take some of the cradle and mounts tomorrow. Here's the car:
In the past few weeks, we got the transmission clearanced for the N* starter, and bolted that up. Today we finished up the cradle modifications, and it goes down to the powder-coaters on Monday. We are using a modified Fiero front trans bracket, that uses a Dodge P/U engine mount. The stock N* front engine mount is being used. The stock rear Fiero trans mount is being used (Except with a RD poly unit). And the back engine mount is custom, again using a Dodge P/U mount (Can't beat them for $5!). I'll be adding a dogbone up top eventually. We got an aluminum flywheel ordered, I'm not sure how or where, but my friend found it for $400!!! That's the price of a stock Fiero aluminum flywheel! It's in, although I haven't seen it yet. We still need a clutch, going to Clutchnet for that (I've heard enough Spec horror stories that I won't ever go back).
The real pride and joy, the headers. My friend gassed up the welder, and said he'd buy all of the materials if I would build him headers. I started my new job, and am aching to get back into working on projects like this, but am saving my own money for a Jeep SRT8, so I jumped at the opportunity. The headers will be long tube, equal length, 180*. I just can't get over the sound they give, it's biblical. However as we all know, that's not going to be easy. So I'm going to order the piping, and see what I can come up with. Fortunately, with the 6500rpm redline and tame 275 cams, the primary lengths will be long (I'm guessing 36" at least), so I've got plenty of distance to get the collectors placed right to feed from both banks. I actually think I'll have plenty of room for the headers themselves, from the looks of it so far, my 3.4 was far tighter on space constraints. My problem with this is going to be the exhaust. I really want to run dual mufflers and a true dual exhaust, as a single muffler is too loud. However, we also want to keep the trunk, which severely limits exhaust options. Since the swap is still in its initial stages, I've got time to plan. I'm open to ideas.
No pictures yet, I'll take some of the cradle and mounts tomorrow. Here's the car:
04-12-2009, 03:24 PM
#4
0.5 BAR
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Join Date: Nov 2008
Posts: 166
Got the cradle back, looks spectacular. Full sandblast and gloss black powdercoat. The prices went up, but with the economy I'm not surprised. Worth it to have it done right. Next step is wiring, and collection of parts/design for the 180* headers.
04-12-2009, 03:27 PM
#5
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Join Date: Nov 2008
Posts: 166
I also ordered the header piping. 24 1.625" U-bends, 3" radius, 8" legs. 2 N* head flanges, 2 4-1 formed weld-on collectors, and 3 2.5" U-bends, 3" radius, 10" legs. All mandrel bent, 18 gauge mild steel. Should make for a good start. They should be here this Friday 4-17.
04-12-2009, 10:20 PM
#8
0.5 BAR
Thread Starter
Join Date: Nov 2008
Posts: 166
Thanks guys! It should make for a great driving Fiero. Smooth, torquey, and power to go with it. I think it will leave a bit to be desired power-wise, but we'll see. I'm hoping for around 275whp on the dyno, so it should be good for mid 12s pretty easily. I guess that's not bad, but I've never been overly impressed with the N* overall. I hope I am by this one though.
I see the similarities, but I definitely would go for the Fiero personally.
I see the similarities, but I definitely would go for the Fiero personally.
