Pulled the trigger on some new headers

"GTRZILLAR32-Now saving for Godzilla and a condo" (jackolson) 12/01/2015 at 22:46 • Filed to: PARTS

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This deal was too good to pass up. Didn’t want to do any power adding until I reinforced the rear subframe but I’ll throw these on with some 400 cell cats and wait till spring/summer for a new muffler and tune.

Arben72 > GTRZILLAR32-Now saving for Godzilla and a condo 12/01/2015 at 22:49

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Link?

Chan - Mid-engine with cabin fever > GTRZILLAR32-Now saving for Godzilla and a condo 12/01/2015 at 23:22

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What happens to E46 headers? I thought header failures were strictly a Ferrari thing.

e36Jeff now drives a ZHP > Chan - Mid-engine with cabin fever 12/01/2015 at 23:52

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Nothing happens to them, they just dont flow very well because BMW shoves the cats 2” from the head and basically builds a log manifold in front of it. Short of going f/i, its the biggest single power-adder you can do for a n/a BMW engine.

GTRZILLAR32-Now saving for Godzilla and a condo > Chan - Mid-engine with cabin fever 12/01/2015 at 23:53

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Nothing. They are pretty restrictive compared to their OEM European and aftermarket counterparts. From what I have researched these are identical to the Agency Power headers which are replicas of Super Sprint non-stepped headers.

GTRZILLAR32-Now saving for Godzilla and a condo > Arben72 12/01/2015 at 23:54

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Fabspeed.com

JGrabowMSt > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 00:00

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I want to hear it when it’s done. In person.

I demand.

GTRZILLAR32-Now saving for Godzilla and a condo > JGrabowMSt 12/02/2015 at 00:22

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Hopefully everything will be ready for the first C&C New Canaan! Hoping to get video of completely stock, headers + 400s, and then the headers/400s/SGT Scorza muffler.

AddictedToM3s - Drives a GC > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 01:04

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NIIICE! Are those Agency Power headers? Why you no super sprint stepped headers?

Chan - Mid-engine with cabin fever > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 01:25

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Why would OEM US headers be so different from the European headers? Do the US ones have integrated cats?

Fabspeed proudly proclaims on every one of their header products that “the factory headers are prone to failure.”

Echo51 > Chan - Mid-engine with cabin fever 12/02/2015 at 02:50

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Just like dealers sell you stuff because it’s needing service. Oh my!

Smoggi - powered by 3 cylinders > Chan - Mid-engine with cabin fever 12/02/2015 at 03:45

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Emissions obviously. There is a reason US S54s have 333hp while euro ones have 343.

GTRZILLAR32-Now saving for Godzilla and a condo > Chan - Mid-engine with cabin fever 12/02/2015 at 07:29

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Yes the US spec headers had integrated cats to pass emissions. Example A:

and these are what Euro spec headers look like:

BiTurbo228 - Dr Frankenstein of Spitfires > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 07:49

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Nice :) I do like a good exhaust.

Curious though. Are the stock BMW headers a 6-2-1 design? Based on quite a lot of reading I’ve been doing about exhaust manifold design that’s a bit of a compromise.

They’re miles better than a log manifold, but compared to a proper pulse-tuned 6-3-1 or high-rpm 6-1 they produce flat spots through the rev-range where the resonances work against each other. I think they do start adding power by design at the top of the rev-range, but it’s still a net loss compared to a proper extractor manifold.

Is there not enough space in the engine bay for an equal-length 6-3-1 (they are quite bulky)...

GTRZILLAR32-Now saving for Godzilla and a condo > BiTurbo228 - Dr Frankenstein of Spitfires 12/02/2015 at 09:40

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There are a couple of brands that do custom headers but those cost an unreasonable amount. Most M guys go with stepped headers as those tend to increase both hp and tq across the entire rev range. But the design are two separate manifolds in a 3-1 configuration. The rest of the exhaust are dual pipes until the muffler. You can swap an x-pipe into the second section but it doesn't affect power.

JGrabowMSt > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 09:48

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if you need help with video, I have a sweet camera rig, and I’m not shy about driving around.

BiTurbo228 - Dr Frankenstein of Spitfires > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 11:58

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Gotcha. How much power do you expect to have with the 6-2-1 headers in place?

It’s odd to think that BMW goes all-out with tuned-length bellmouths contorted and wedged into what little space there is in the inlet manifold and go with an exhaust design that’s been known to be inferior since the 60s...

Makes me wonder how much power and torque they’d be making with a proper setup though. Considering that the Euro S54 is at 338bhp/269lb-ft, and that a properly designed 6-3-1 took an otherwise stock Triumph 2.5PI from 132bhp/153lb-ft to 154bhp/195lb-ft.

That’s on a 6000rpm redline OHV 2.5l from the 60s. Imagine what it could do to an 8000rpm redline DOHC with VVT 3.2l that’s on par with the TVR Speed 6 for being viewed as the pinnacle of NA I6 engine development...

GTRZILLAR32-Now saving for Godzilla and a condo > BiTurbo228 - Dr Frankenstein of Spitfires 12/02/2015 at 13:25

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The S54 can make some serious power, unboosted, if you are willing to put the money in. Google Dafoes engine rebuild and you will get the idea. Really all I want is to make 100 hp per liter to the wheels without boost.

BiTurbo228 - Dr Frankenstein of Spitfires > GTRZILLAR32-Now saving for Godzilla and a condo 12/02/2015 at 18:44

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100bhp/l at the wheels! Nice :)

Just looking through that thread now. What an engine :)

B_dol > GTRZILLAR32-Now saving for Godzilla and a condo 12/14/2015 at 14:22

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Very nice, headers are on my list for the /M coupe once a few other items are sorted out.

GTRZILLAR32-Now saving for Godzilla and a condo > B_dol 12/14/2015 at 21:14

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I hear ya. Like I said I really wanted to reinforce the rear subframe and make the switch to poly bushings first but that deal was just too good for brand new headers.