Quote:
Originally Posted by EIN M
OK, so I'm a little confused.
a) How does the composition of the "ends of the downpipe" affect flow? Wouldn't the shape be the determining factor?
b) Does this mean that entire DP is not 100% SS?
|
The composition itself does not affect flow, but using a casting process to create the end pieces allows for much more complex shapes than simple tube bending and hand fabrication. The bellmouth shape of the cast flange portion improves flow.
The downpipe is still composed of 100% stainless steel.
Quote:
Originally Posted by PHANTOM
I hate to sound ignorant but what exactly is the benefit of changing out downpipes? And how involved is the install on the 1M?
|
Aftermarket downpipes eliminate the catalytic converters found in the factory downpipes and improve flow by a substantial margin. The 1M engine bay is a bit tight, so I’d suggest a professional install.
Quote:
Originally Posted by fastauto
+1. I am new to the bmw world but have been having fun with turbo cars for a long while. I am shocked to see so many people not looking for a true 3" setup. Is it because the majority of people running these engines retain the stock turbos thus you dont need the larger plumbing?  |
The 2.5” downpipe only has to flow enough air for 3 cylinders, and the link pipes and collectors remain 2.5” throughout, so there are two pipes going all the way to the middle of the car. I believe that you can achieve a very high power figure before choking such a setup.