Avve

After having a closer look at my exhaust system (1986 Euro 16V) I realize that it consists of no cats, both pipes go into a large central muffler, then two pipes exit widely to each side into a rather large resonator before both pipes join into the rear muffler. The pipes are (physically) more separated than the US 85-86 but not "true" duals" all the way.
The future combo headers + x-pipe + large resonators mean that I may have to keep some sort of rear mufflers, perhaps ending it all with a pair of SuperTrapps!?
The weight has to be kept as low as possible. This is meant to be a race-car with plates (and of course I need all the power I can get)

Carl Fausett

The good news is that the system is modular. Start with the RMB only. See what it sounds like. Its pretty mild and sounds good.

If you want more HP and can stand a little louder note, add the Header-x and remove the cats.

If you still want more HP, then add our hi-flow resonators/dual exhaust as the last step.

Manfred

thanks for your input Carl.

Manfred

Carl, as a second thought, not sure if I was clear earlier, but what I'm really going for is the most HP increase with the least sound increase; does that change your recommendation? Thanks, Dan ('91GT with stock exhaust)

The_Remora

Anyone have a chance to compare this header/x-pipe combo against a standard ott/motorsport x-pipe? would be interesting to see the difference or how much more power it can produce.

Imo000

Carl,

Any concers for only sampling one bank with the O2 and not both?

Looks good!

hacker-pschorr

Most 928's running headers have been doing that since day one, no issues to speak of.
I haven't seen very many who went the extra mile to add an O2 bung in the collector.

I have four on my 81. One to test back pressure, one for the stock narrow band (in the right bank manifold), another for wide band, and the fourth is used at the dyno since I don't like using the tail-pipe sniffer.

RyanPerrella

Question

1) Why aren't your X-pipes mandrel bent?

2) How come that GT in your chart only made 256 HP at the wheels? that seems 20-30HP shy honestly? Was that car running with a "banana in the tailpipe?"

Carl Fausett

There are two O2 bungs provided. The MSDS Headers have one in one collector, and I added one into my Header-X-Pipe on the oppposite side.

I figured the owner would want one for the stock O2 sensor, and the other for his wide-band O2 sensor...

Because of the frequency of the turns needed in the length of the run. The "mandrel" of most mandrel benders requires 14 to 16 inches of straight tube - about 8 inches to each side of the apex. If you need to make two bends in a 12" length, your choices are either 1) mandrel bend two pipes and cut and weld them together, or 2) ram-bent tubes.

For this application, considering how mild the bends were (they are not very tight bends) ram bending was a good choice with a smooth interior and keeps cost down.

Dont forget mandrel bent tubing with welds add turbulance on the inside (where it counts) at every weld.

osborm

Hi carl interested in this article on headers and x pipie:

https://rennlist.com/forums/showthre...s+x+pipe+928s4

these would wake my 928s4 up but what would the cost of shipping to United Kingdom be cheers mike.

Carl Fausett

Mike: I cannot produce a shipping quote from a partial address.

Send your complete address to shipping@928motorsports.com and we will get you a price. We do a LOT of international shipping - its no problem.

steaditim

bump

edi1

hi have x pipes headers on my 88s4 with no cats. there is no ruble sound

but its sounds nice.

Chuck Schreiber

Anyone running this setup??
Feedback appreciated!

blau928

The O2 bung in one bank still does not make it right even if no claimed problems by owners. The correct way is to put the bung in the middle of the "X" so that the sensor can read all cylinders. If you have a wideband on one header, and a narrow band on the other header, you will get wideband for one side, and the ECU will only be able to get information on the other side.

This picture is a setup from about 6 years ago with the proper placement of the O2 sensor with "X" pipes and headers using the Factory LH Computer. Both sides of the "X" have a bung so that a wideband and narrowband can be used. (The stock S4 exhaust has an "H" pipe in which the sensor is mounted.)

Only if an aftermarket ECU with DUAL O2 channels is used can you have one sensor per bank like the header is currently shown in Carl's setup.... Otherwise, the LH will not be able to read any information from the passenger side cylinder bank and correct accordingly...

I have mentioned this before, but it seems that too many go along with the "look" factor instead of proper design for intended use.. (The only other setup I have seen to date with the correct setup using an LH is Todd's..)

Anyway, enough of my rambling...