mx5cartalk.com

Hey guys, for those that don't know I'm building a Locost Clubman track car viewtopic.php?f=87&t=74090&start=15
I'm about to purchase some bends to make the headers. Here's a photo, for clarity of what i'm doing, this is not mine, I have the BP4W donk.



I measure the OD of the OE NB8A headers at
Primary's 43 - 42.5mm
Secondaries 38
exit pipe 50.5

My engine is stock at this time, it will get tickled up over time. I know what I put on there wont be perfect but keep in mind the engine will live at 5000-7000 RPM

Primary size is my biggest concern ATM. I have a choice of either 44.45 or 41.28mm. Everything I read tends to recommend smaller, so thinking 41.28mm ???

I know the final exit will be 2.25 inch (57.15mm)

In my build thread it was briefly talked about. So I'll acknowledge the comments some of the guys added on the subject. In no particular order.

Magna_blue wrote
Long 4-2-1 headers as well, rascal, rather than 4-1? I'm thinking better spread through better scavenging throughout the range.

93 Clubman wrote
Yeah, 4-1 suits top end - go with the NB8A OEM headers if they'll fit the build. The ADM ones were fairly good, however the USDM ones were rubbish. There are/were some comparison pics on here somewhere.