Northstar 88GT 5-speed BUILD THREAD

[Atilla the Fun]

Both are all-aluminum, 32 valve, dohc, 4.6L, 300 hp V8s. They're gonna like similar size headers for similar rpm ranges. Make has nothing to do with it. Due to such mild cams, and being under 350 real HP, even with headers, exhaust and CAI, I think 1.625" is just about right.

[Aaron]

I was wondering, because a N* isn't so different from the Cobra's engine, and those guys generally go 1.75" because they want high-rpm power rather than midrange torque. But considering the huge cams offered for their engines,...

They are actually very similar, but like Will said, this N* is otherwise a stock 300hp. Not to mention, the Cobra's have a blower on them, with dramatically affects the primary sizes.

[The Dark Side of Will]

'02 and earlier are N/A. I assumed that's what you were talking about.

[Atilla the Fun]

I was referring to the pre-'03 Cobras

[Aaron]

Got an update, I started and got halfway finished on the last header. 75% done! Still equal length, everything's going smoothly, it just takes forever.

[Shaun41178(2)]

I see tranny select cable interference in your future.

[Aaron]

I don't. I guess the pics are deceiving, the cables clear just fine. I spent a lot of time making sure they'd clear, and wouldn't come too close.

[Aaron]

Alright I got the primary for cylinder 7 all mocked up, and mostly welded. It's good, though may be tight against the trunk, we're no sure yet. I was going to do #1 today too, but I've got other stuff to do. I got it planned up with the copper tubing, but haven't started the pipe work. For now, here's the exhaust plan. For the bottom header, turn 90* towards the rear of the car, run under the cradle, then out the passenger side. The top header will turn down and head towards the passenger side of the car, then make a U-turn, and exit the driver's side cutout. Not sure where I'm going to put mufflers yet.

[fieroguru]

Looking good! I would double check the clearance between the tube going along the edge of the tranny and the driver side frame rail... it looks close.

[Atilla the Fun]

You're doing very well, but let me play devil's advocate for a sec: All that work, all that complication, for maybe another 15 ft-lbs in the mid ranges and 15 hp at peak, as compared to a custom shorty header, and still less power than dropping the compression with forged dished pistons, and combining a pair of T4S04s with regular GM cams. How much weight, exactly, are you adding with all that tubing? Heck, boost might've been lighter, too!

[Aaron]

You're doing very well, but let me play devil's advocate for a sec: All that work, all that complication, for maybe another 15 ft-lbs in the mid ranges and 15 hp at peak, as compared to a custom shorty header, and still less power than dropping the compression with forged dished pistons, and combining a pair of T4S04s with regular GM cams. How much weight, exactly, are you adding with all that tubing? Heck, boost might've been lighter, too!

I'll bite.

Yes, it's a ton of work. But it's work I enjoy, and I'm very proud of how they look so far. It's my hobby, and building shorty headers would be cutting corners, when it doesn't cost much more to get the best headers that can be made, just more work, which isn't a problem.

It isn't just the power, it is also the sound. This should be the best sounding Fiero, period. Maybe, maybe fieroguru's might have a chance. People spend a lot of money to make their cars sound good. Ever price a complete Corsa catback for a C5? They are $1300, and don't add very much power. My complete exhaust system, including the headers, is about half of that, sounds better, weighs less, and adds more power.

As for the weight, the headers shouldn't weigh any more than the stock manifolds. I'll weigh them when I'm done.

It isn't all about the power. Ever driven a low compression turbo motor? The loss of low speed torque is staggering, between the compression loss and turbo back-pressure. Plus it opens the door for imperfection. My 3.4 isn't bad, but it has its quirks. The N* will idle, drive, cruise, and perform just like it did in the Cadillac, just with slightly more power and a much better noise. It'll retain the perfectly smooth idle, the smooth acceleration, the Kansas flat torque curve to 6500rpm, etc.

[Aaron]

Just a few videos, remember these are OHV, high displacement cammed V8s, the N* should be much smoother.

http://www.youtube.com/watch?v=MSZTbR6C6Lw
http://www.youtube.com/watch?v=CAOqx_Fq ... re=related

[CincinnatiFiero]

That Swedish fiero with the 540i motor and 180* headers wins sound sorry, that was magic in the forest.

This will be a close second, don't disappoint.

[Aaron]

You haven't heard this one yet

That one you're talking about did not have 180* headers as far as I'm aware, just a stock 4.0 SOHC.

[Unsafe At Any Speed]

Can't wait to see (and hear) this when it's done.

[fieroguru]

That one you're talking about did not have 180* headers as far as I'm aware, just a stock 4.0 SOHC.

Without the firing order, I can say for 100% that they were 180* headers, but they sure look like it... Too bad there was never a pic of these headers on the engine/tranny.

[CincinnatiFiero]

I'm almost positive in the two posts that guy made he mentioned they were 180*

[Aaron]

Without the firing order, I can say for 100% that they were 180* headers, but they sure look like it... Too bad there was never a pic of these headers on the engine/tranny.

I stand corrected. No one would go through that amount of trouble and not make them 180*, unless he is a complete fucking moron and screwed them up, but that I doubt. That makes much more sense, because that car did sound really good. I can't seem to find the videos though, any links?

I've got one worry about the N*. I never really thought they sounded that good. For a relatively low displacement, DOHC, 32v V8, I expected a better sound. Part of that is even with the 300 cams, at redline they still don't sound like they are making much power. There's no scream, there's no intake roar that overpowers the engine, nothing, just sounds really tame, and at redline, it sounds like it's only turning 4000rpm and barely breaking a sweat. On contrast, the 3.4 DOHC makes noises very few engines do. At 3500 it develops a deep growl, and at 6500rpm that motor sounds better than most I've ever heard. It just sounds like it's sucking in people's babies, and distorting the earth's axis with its power. The N* has none of that. I'm hoping these headers, with a good CAI, will extract some of that DOHC growl that I know the N* has hidden somewhere.

[Atilla the Fun]

Yes, it should sound great, and your work speaks for itself. They do look a bit snug to the trans, but I'll let that thought go until I you've had a chance to drive the car and tell us how it works. I do know about the dogginess when not boosing a boosted engine, and you'll have great driveability, if you go no wilder on the cams than Cad's own 320-HP cams. In fact, you'll have better driveability than my torquey LSX/F40 will give.

[fieroguru]

I do not know if these links still work (no video viewing at work), but they were for videos of the BMW.

http://media.putfile.com/video1-20

http://media.putfile.com/video2-94

http://media.putfile.com/video3-82

http://media.putfile.com/video4-75