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Topic-icon Merlyn Black Magic Waste Gates on Seneca II

23 Sep 2021 16:15 #3179

I just spoke to Suzanne at Merlyn products.
She told me that Merlyn estimates installation of the Black Magic waste gate system on a Seneca will require 12 to 16 hours. That is for one system on each engine.
When I asked if it was a complicated installation, she told me any competent A & P mechanic should have not trouble installing it.
You can obtain a copy of the installation instructions by writing to Suzanne at: .

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19 Sep 2021 18:42 #3175

Where did you have it installed?

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13 Sep 2021 12:55 #3171

Hi Jamie;
Thank you for taking the time to address Stephanie's question about the Black Magic wastegate control STC.
From the engine times you're quoting, you must know how to fly your engines.
If you have time, I'd like you to write up your tips for operating your engines. A brief step by step description of the changes (GAMIjectors, Black Magic, etc) you've made and what effect they have had, and the power settings, mixtures, etc. that you follow during a typical flight.
If you're able to post that here on the forums, we could archive it and pass it to other Seneca owners.


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12 Sep 2021 00:05 #3170

I have them on my Seneca II. I highly recommend them. They work well. In addition to increasing critical Altitude, they also help remove any throttle split at higher alt due to fixed wastegate settings. My engines are about 800 hrs over TBO. I like to run them at min RPM for the conditions. I can get 75% power at FL220 and 2300RPM. Best you'll do with fixed waste gates @2300RPM is about 12K. I also run mine lean of peak. I burn about 19 GPH total. I lose a little power, but the pay off is worth it. I lose about 7 KIAS vs running rich of peak and I'm burning about 5 GPH less. With a 123 Gal tank I can fly 200NM farther, and only lose about 5 min on a 4:15 hour leg. I've only had one maintenance issue with one. The mount cracked. I pulled it and sent it back to them and they replaced the mount.


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03 Sep 2021 02:28 #3160


Did you ever get any info on the Black Magic wastegates? I am curious what people think about using them as well.


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  • Stefanie Curland
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29 May 2021 03:14 #3001

Am looking for feedback on those who have installed Merlyn Black Magic Waste Gates on their Seneca IIs. Are they functioning as expected? Are they worth the investments? Have they presented any maintenance issues?

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