The manifold mechanism is changed so that it is fully open at ca. 50-75% of the travel and then actuates the waste gate with the remaining travel
How does that achieve a constant MP at full throttle?
The TB21 installation seems to maintain a constant 30" MP, I think. I wonder how that does it? I do know of one TB21 owner whose plane was grounded for 6 months while Air Touring (the Socata dealer!!) were trying to work out how to adjust it…
RCM was taken over by another guy Carl Lee. I have dealt with him a number of times and he is very nice and cooperative.
If there is serious interest in the turbonormalize version of the TB20 I would suggest to contact him directly. He might be tempted to do the work.
Turbonormalizing makes a lot of sense and is not very expensive.
No constant MP with the manual wastegate, you have to adjust it. Not as comfortable as an automatic wastegate in e.g. the SR22TN but simpler, cheaper and safer.
It does sound like you could blow up the engine with this…
It does sound like you could blow up the engine with this…
Just ask people who rent out older Senecas and similar aeroplanes 
The only protection are two tiny yellow “OVER BST” lights next to other totally unrelated annunciators but far away from the MP and RPM gages where you normally look when setting takeoff power. When you notice the overboost lights, you have no idea for how long and how much you have been torturing the engines and how much damage has already been done.
Regarding the initial question: Why not talk to a licensed design organisation about the cost and timescale involved? The really difficult part about that turbo installation is not the engineering, but the paperwork. With no previous experience you can easily waste several years for nothing. Getting someone to do it for you may look costly in the first place, but save you some precious and irrecoverable lifetime. For a previous company, we had Röder Präzision (http://www.roeder-praezision.com/en.html) do a modification of an airplane. It was not cheap but fast and efficient and went through the authority approval procedure in no time, test flying included. They have an EASA design license, but I don’t know if also an FAA one.
I contacted Röder a few weeks ago about something else and they absolutely refused to communicate in anything but German. Basically the phone call gets terminated there and then 
This would be for N-reg only – one would not bother to hunt around for the much smaller number of EASA-reg TB20 owners who fly IFR seriously.
The straight approach is to throw money at a DER, which is the FAA equivalent of an EASA 21 company but the authority is vested in an individual person who works freelance. Obviously one would start with a company which makes the various bits and/or has the experience already, and they are prob99 going to have a DER contact already. The DER generates the design package which is used to apply for the STC.
Nowadays one can use the FAA STC design data to apply for an EASA STC also. Certain UK avionics shops get customers to pay 2k+ for the DER package (which is not actually necessary, especially if the product comes with an AML STC!!!!) and then use the data to get an EASA STC which they sell on. The BASA provides for this mutual design data acceptance, but the treaty is largely empty because there is no STC acceptance and there is no assurance that EASA will grant the STC… it seems to work for trivia like screwing a GPS into the panel but a turbocharger is more complicated.
I contacted Röder a few weeks ago about something else and they absolutely refused to communicate in anything but German. Basically the phone call gets terminated there and then…
But they have an English website. Well, in case you need a translator, you know who to ask…
The straight approach is to throw money at a DER…
“Throw money” may be the right term. I think in the end it will be cheaper to leave the TB20 as it is and buy a Turbo Arrow or Cessna 210 with good engine times for the money that the turbo installation alone will cost.
According to the website RCM uses exactly the same equipment as the TiO540 of my 114TC.
That means automatic wastegate.
You might also give Gomolzig in Germany a try. Have seen quite some heavy structural mods from them. They also make and design exhaust systems and are DOA, so they might be able to do the work. I don’t know if they do FAA as well, but you might be able to use the bilater agreement the other way around.
