Hi Rob,
I wouldn't worry too much about the 9.7 rotors. On advice from Leon Promet and others I deliberately installed these in my turbo 13B. I could hear the onset of detonation at 44MAP during runup with a fixed pitch prop. I reduced throttle and it went away.
Once I got my variable pitch prop I never experienced detonation again. I do keep the mixture on the rich side.
The one difference is that I have 3mm seals.
I think the turbo makes a good muffler, but the boost is nice too. Might as well use it :)
Regards,
John Slade

Rob wrote:

Hi everyone,

I am preparing my Bruce Turrentine 20B hybrid engine for my BD-4. As I am thinking about all the details it occured to me that a turbo would be a great muffler based on the experience of those on this list who have them. It turns out that the price of a good turbo has come down to the point that it is almost as cheap as it would be to fabricate a good inconell exaust system. Then I can use it for boosting the engine too.

Is it reasonable to think like this? What do you all think of this proposal?

 

 

The only problem is that my 20B has the high compression 9.7:1 rotors and I'm concerned about detenation. Is it possible with the right components to maintain sealevel pressure on take off at full throttle and then maintain 30" MP as I get higher?

 

I have yet to figure out what components I need to do all this. I have been reading as much as I can about turbocharging but I can't seem to get good answers to the above questions.  Does anyone know a good place to go to learn more about turbocharging for aircraft or how to select components for a specific mission?

 

 

I would appreciate any comments or criticism on my musings. Brief or extensive coments are welcome.

 

Thanks everyone.

 

Robert Bollinger

Currently flying a BD-4 with a Ford V6