Schnell Headers on 986 with Stock Exhaust

[Adam]

Originally Posted by bmwm750

I have the new FabSpeed exhaust, and unfortunately yes, it does drone in the 2-3k range. I am still on stock headers, but am looking for ideas there. The FabSpeed headers are gorgeous and I am sure will not cause any CEL related issues, but damn are they pricey.

Heres my latest idea for a perfect exhaust for these cars: High flow catted headers (a la FabSpeed) to guarantee improved flow and scavenging, yet also no CEL related issues. Secondary cat deletes. Now, heres where I would like to think I'm onto something: Stock 03 muffler, but with RPM activated dump valves (almost like turbo wastegates) BEFORE the muffler section, that begin to open at say, 3500 RPM, and are fully open by say, 4500 RPM. With this design you have a perfectly quiet car for normal driving and cruising, with no resonance issues, yet when you get on the power, as the RPMs rise and you get into the meat of the power curve, you get a very free flowing exhaust, that will sound glorious as well.

Anyone else think this could hold some promise? I have a very qualified shop here that could do the work on designing a system like this, and we could have a prototype I'd be happy to test.

Patrick

Bogg tried some valves like that on his stock muffler and the results...well lets just say some people liked it and some didn't. It didn't sound very "exotic." I'll try to find the videos he made. I do like the idea of using the stock muffler though with headers and bypass pipes. I think that would make a good combo.

http://www.youtube.com/watch?v=08-uX9z_Rg4

http://www.youtube.com/watch?v=vpXhUN6-vsk&mode=related&search=

[panameras]

and with straight through pipes! http://www.youtube.com/watch?v=M1VI-rTaUmU

"Stock 03 muffler, but with RPM activated dump valves (almost like turbo wastegates) BEFORE the muffler section, that begin to open at say, 3500 RPM, and are fully open by say, 4500 RPM. With this design you have a perfectly quiet car for normal driving and cruising, with no resonance issues, yet when you get on the power, as the RPMs rise and you get into the meat of the power curve, you get a very free flowing exhaust, that will sound glorious as well.

Anyone else think this could hold some promise? I have a very qualified shop here that could do the work on designing a system like this, and we could have a prototype I'd be happy to test.

Patrick"

I like that idea very much. A bit like F430s when the cams open up at higher rpm. Not saying it will sound like a ferrari but the sudden "explosion" of exhaust note of a flat six should still be as sexy.

[edevlin]

"Genuine Gemballa Headers on eBay! $1445usd!

http://cgi.ebay.com/ebaymotors/GEMB...sspagenameZWDVW

I wonder if these are indeed $870usd better than the $575 Maxspeed headers!"


I dont know, but most of the mechanics I talk to say that good headers for our cars are not cheap, because of the low volume of units sold. I think my german TTP headers for my 2.7L were 1,800.00. The shop that installed them loved them, they said the materials, welds and mating surfaces were as good or better than stock parts. They also said they had experience installing and then removing some pretty poor looking and fitting headers from other manufactures.

Ed

[Cloudsurfer]

I am familiar with Bogg's setup, and the main problem with that, in my opinion, is that you are stuck with the valves in one position, at all RPMS. That sound is going to be great at higher RPMs, but sound AWFUL at low RPMs. Many modern cars employ systems similar to this (Corvette, F430, etc) to gain the benefits of both a quiet exhaust for cruising and a free flowing exhaust for power.

The question to be resolved for my idea, is how to control the valves. Vacuum? Electric Servo? One hypothetical advantage of vacuum or pneumatic control, would be that at higher RPMS but low power settings, there may not be enough force to open the valves, which could be a good thing. I'd look at starting to open the valves somewhere around 3500-4000 RPM, and have them fully open by 4500-5000 RPM. This way, you are not intruding at all on cruising noise levels.

This may be a winter project.

Patrick