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Nux Nux is offline
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Join Date: Mar 2016
Location: Copenhagen, Denmark
Posts: 684
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Originally Posted by Pehlen View Post
So, this has me looking at headers. I have a Fabspeed cat bypass and an M&K GT3 1 in 2 out, but obviously still have the unequal length stock exhaust manifolds.

We also did a few dyno pulls with the screens off the stacks and then with the stacks off completely. No surprise with no stacks ~40RWHP off. Without screens provided about 1 additional HP. We did these pulls because there was a big dip in AFR around 5000 RPM, right after a relatively large peak in AFR. We were trying to determine if that was a result of a harmonic in the intake or a restriction somewhere in the system. While the pull without stacks was off, it resulted in a very flat AFR curve - leading to the belief that it was a harmonic. While I’ve read a lot on tuning the intake runner length, it’s satisfying to watch it in action with the dyno.

In the near future, I plan to take a couple of trumpet sizes in to test them out. And now probably with equal length headers!


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That is very interesting. Can I ask how long your stacks and complete runner lengths are? See post 150 for correlation btw intake runner length and harmonics.
Old 11-20-2017, 06:24 AM
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