Al/ Chris,
I'm certainly no expert on Turbo, nor are some who purport to be experts. There are those who are genuinely very knowledgeable in car turbo, but for aircraft use it's another matter entirely.
From discussions on here and other sites, it would appear to me that Turbos fail because of the high heat at high rpm over extended periods and the overspinning in thin air at altitudes. All that sounds fair and reasonable to
me.
Some builders have overcome these problems by trimming internal blades and making the waste gate as big as possible - in other words making the internals so that the exhaust has more room to escape, placing less stress on the
turbo.
I notice that some car applications have remote turbo allowing the exhaust gasses to slow and cool before entering the turbo. For our application we don't need all the energy from the exhaust, so we don't need all that heat
and exhaust pulses hammering the turbo, as it does continuously if it's in close proximity to the engine.
For my application, if I need turbo, I will place the turbo remotely and only bypass enough exhaust energy, by way of a 'Y' section in the exhaust pipe, to the turbo. The bypass should be cockpit adjustable for different applications
requiring different energy requirements - as in the wategate..
Hope you see some merit in my thinking.
George ( down under)
I know you're fairly entrenched in the 13B approach, but for the sake of
discussion, I'm not sure that's a valid reason.
How high do you want to go? I think
Tracy's been over 15k with an NA
13B. I'd be willing to bet that a Velocity with an NA 20B could get well
over 18k without a problem.
As I recall my analysis those many years ago; the cross over point on power for a turbo-normalized 13B and a NA 20B is at about
13,500’ msl. Above that altitude the torbo 13B will do better. Of course you can boost the 13B to more than 30” and get more power.
Al