Just wanted to share that. They're 1 3/8 primaries which should work better than the 1.5" headers I see most people selling.
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Just wanted to share that. They're 1 3/8 primaries which should work better than the 1.5" headers I see most people selling. -
This is also posted in the group buy section here. Oops. -
Sorry, but what makes you say 1 3/8 primaries are more ideal? That is the exact opposite of what is actually the case. They are anemic, maybe better for packaging (space tolerances) but certainly not for any power gain. I would only expect a slight bump on a bone stock 1.8L M10.
If you wanted a good E30 1.8L M10 header, that alpina header a couple threads down was a screaming deal.Comment
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Feel free to post what you think is ideal, I'm not a header expert.
For reference, the stahl website shows three headers available for the m10 318i with "size" which must mean primaries at 1.25, 1.375, and 1.5 which says "race only". What race only means is up to interpretation.
It seems like a lot of the 2002 headers have 1.5" primaries, and thus a smaller enginer should have a smaller header. I guess it depends on where you want to see gains.
You get quite a different story if you refer for A.G. Bell's book "Four Stroke Peformance Tuning", where the low end for cylinders our size with "street cams" is 1.625.
Honestly it's all just internet banter until someone can post dyno data of back to back runs with different headers.Comment
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