To headers or not to headers......

[e30 x2]

Wierd, as Gus said, with those BTB headers, you lose power and torque below 3500rpm. Why would that be?

correct me if im wrong but the power band moves with the increased flow (not always) but at higher rpms you get more power. Just like the s14; if you want more power out of a smaller displacement you need to raise the rev band and increase flow.
Anyone know why no one makes 6 into 1 headers for the m20? Seems like the single collector and following piping to muffler would be better for flow and weight reduction over the stock two pipe design. Ive found threads about choices of pipe size and sound but not so much about the actual performance gains, nor anything about 6 into 1 headers. Sorry if this constitutes a thread jack but i thought it relevent to the initial question.

[Ball325]

Wierd, as Gus said, with those BTB headers, you lose power and torque below 3500rpm. Why would that be?

not enough back pressure as there isnt enough air flowing yet, maybe?

[StereoInstaller1]

OK, so all the misinformation regarding headers can be understood clearly, by reading an in-depth article found here I would say the loss of HP below 3K on the graph discussed earlier is more caused by tuning.

Luke

[matt]

OK, so all the misinformation regarding headers can be understood clearly, by reading an in-depth article found here I would say the loss of HP below 3K on the graph discussed earlier is more caused by tuning.

Luke

You mean the tuning of the headers? They are probably just too big.

Same thing happens when you put a trackpipe on an e36. Car feels faster because there is a bigger difference between lower and higher RPM power, but it's actually slower.

[MrK]

Eureka! That dyno graph on the site that sells the 6-branch "18hp" headers got me thinking that the reason my stroker dips at 3000rpm is because of my HEADERS! And all this time I'd been trying to play around with the ignition timing and afr with no success... no WONDER!

Well thanks to the poster of that link, and sorry for going slightly off topic.

On-topic: I have a set of Alpina headers that seem to have the same effect as those B2B ones... increase of hp up high at the expense of some torque down low at exactly 3000rpm, probably due to the fact that my headers are not perfectly matched to my engine (Alpina headers and a custom high-comp stroker)....