Chris,
I also agree with everything Mark and Al. said. For me, I chose the turbo because it fit better in an RV-6 and was simple to do (I had a turbo just sitting there... had it at least put it on and try it. It can potentially provide much better power/weight at high altitude. But in general, Al's 20B makes more power than I want to risk with my turbo 13B, and the 20B will stll make more power than a n/a 13B at altitude.
On Wed, Mar 17, 2010 at 7:55 AM, Mark Steitle <msteitle@gmail.com> wrote:
Chris,
I'm with Al on this one. I chose the 20B for the extra reliability of a third rotor rationalizing that if I lost a rotor, there would be two more to get me home. Also, the 3-rotor is a little smoother as it fires every 120* vs. 180* for the 2-rotor. What we need is an all aluminum 3-rotor!
Mark S.
On Wed, Mar 17, 2010 at 10:29 AM, Al Gietzen <ALVentures@cox.net> wrote:
Chris;
I know little about turbocharging; so I can’t help you on that score. But I did spend some time way back about the decision of 20B vs turbo 13B. That is a fairly even tradeoff, so when you say “that ship has sailed for me” I’d agree.
My reasons for finally choosing the 20B: I think comparing the total weight of the installation there isn’t a big difference – adding the turbo, the intercooler and the extra plumbing is close to adding another rotor and the big intermediate housing. I also felt that adding a rotor added some redundancy, whereas the turbo added more complexity and potential failure modes. It seemed to me that pushing 2 rotors harder to get the power of 3 added stress to the engine; but I think the the rotary can handle it, so that’s not much of an issue. And the 20B fits pretty well on the Velocity.
Given where you are with the 13B; and the collective experience and knowledge now available with turbos in this application; I’d say “go for it”.
Al
Al G did it with a 20b in the same kit airframe. However, that ship has sailed for me.
Actually, that brings up another issue I have been curious about. Why so much preference to a relatively hard to find and expensive 20b over a turbo??????? I noticed it routinely in the achieves. I understand the 20b is more powerful out of the box and the conventional wisdom seems to say the 20b is simpler...tubo's add complexity. Well, the 20b does have an extra moving part <g>....but, unlike the turbo option the 20b does not do much for you in thin air, the turbo does. Also, a 13b turbo install would still seem to be lighter than a 20b N/A install. What am I missing or do we just really like the cool factor of the 20b (no disagreement there from me).
I once again throw myself at the mercy of the collective wisdom for edification. While y'all pine away on it all, I will be confusing myself further doing some more surfing and remind myself of the other questions I meant to ask.
As always, thanks.
All the best,
Chris Barber
Houston, GSOT
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