In case anyone is interested this is the BMW part number that was on my header when I received it.
With the help of David Pan and Mike Krnc, who both own BMW Motorsport Groupe A catalogues,
we learn that this is a 2.3L Gp A header.
Possibly it was also used in Gp A rally competition but it is difficult to know for sure.
There is a lot of myth and mystery surrounding the many different headers that BMW Motorsport
produced for the S14 engine over the years.
|
On the right is a "screen capture" from the BMW Mobile Traditions CD-ROM. These are the various
part numbers that are listed for S14 headers. The factory 2.3L header is listed first.
Interestingly, the 2.3L two-piece Gp A header is also listed. Furthermore, what is billed as
the Evo III header happens to have the same p/n as the 2.5L Gp A header. This would make it
appear that BMW Motorsport had Groupe A competition in mind when they homologated the header
on the 2.5L Evo III (Evo Sport) engine. This header is, as of 12-00, still available from the factory
for around $1200.
Matti Männistö, an E30 M3 enthusiast from Finland, has helped me fill in a few more blanks. From him we learn that the 348 number is the header for the European "no-cat" 2.3L engine. According to Matti, it is similar in size to the 877 header, except that it is one-piece. Matti also points out that the 877 header (i.e. the 2.3L Gr A header) is the same as the Evo II header. He should know, he owns a genuine Evo II. |
|
Click here to read a summary of S14 headers by Gary Bossert. |
|
The picture below shows the inside of the header inlet tubes. One apparent fact is the obvious weld bead along the inside of the inlet where the flange is welded on. It was recommended to me by Don Fields that it might be a good idea to grind these welds down a bit to improve flow. I had thought of that myself, but after careful observation it occurred to me that the header inlet is much bigger than the exhaust ports on the cylinder head. Thus the welds are not really impeding the exhaust flow in any significant way that I could tell. Furthermore, having the header inlets much bigger than the exhaust ports is generally considered a good thing as it helps prevent flow reversion. |
|
Finally the following picture shows the fitting which was welded on by Turner Motorsport and allows
an oxygen sensor to be mounted to the header. The location is not identical, but similar to that used
for the factory sensor. The wire on the O2 sensor is plenty long enough to reach this fitting.
|
|
|