X-Mozilla-Keys:
charles harbert wrote:
Marv, I haven't had a chance to read all of the postings which is why I haven't
responded. If you can send a copy directly to me, I'll know to read it right
away.
My Turbonetics turbo is a T-SO4 with an Inconel wheel. Below is some info from
when I first purchased it.
(May '98)I talked to "Ola" today from Turbonetics (805-529-8995) about sizing
these pieces for our application. He thought that the 62-1 might be too big for
our conditions. After talking with him for awhile, he suggested that we consider
a variation of the T-04E, which is a T-SO4 that has a larger shaft and ball
bearings. This is equivalent to a 58-1. He also said to start out with a 1.30
A/R turbine housing, and we may end up needing a 1.50. The T-SO4 is capable of
very high rpms (120-160K) without destruction. Other airplanes are using them
for high altitude work. By the way, you don't talk about airplanes-he doesn't
want to know. I told him it was "severe off road use-climbing high mountains".
This turbine will cost about $1,800, or about 3 times the normal price due to
the modifications.
The problem with sizing a turbine is the significant change in compressor inlet
pressure. You go from 30" to 5" at 20K'. This produces a huge change in the
pressure ratio which makes the turbine speed up significantly-enough to destruct
if not taken into account. You generally do not want to go over a P/R of 4-5.0.
Subsequently, I found out that the Mazda exhaust is so hot (1600-1700 degs) that
I should go to an Inconel wheel which will allow another 100 degs of safety
(1700 vs. 1600 continuous). I talked to Ola who told me they don't yet have an
Inconel wheel for the large shaft, but are looking into it. They do have a small
shaft unit (pn 10662 SH/P (Inco)/ 1.30/ dry/dyn) for $(under $1K) that they can
put together in 2-3 days. It can be modified to add the ball bearings for higher
RPM use but it takes 2-3 weeks for the special order, plus more expensive
(probably around $1,800?).
He also has the turbo inlet and outlet flanges (3/8" thick-2.25 inlet dia & 3'
outlet dia) (pn 20167 & 20174) and the SS gaskets (pn 30143 &30142-S) which he
can send us. I also think I'll order the Racegate waste gate at the same time.
Marv, there are a lot of varying factors that I spent a fair amount of time
calculating a while ago. However, I'm still early in the testing phase, so I
can't answer your questions, for sure. Like Paul plans to do, I have a way to
cockpit adjustment of the turbo boost which controls the hp. What you run into
is a bunch of other problems(pressure ratio, turbine inlet temp, etc) that make
it difficult to determine the outcome reliably. For example, I can't tell you
exactly how much hp I will need at what altitude in order to achieve a certain
indicated airspeed, because I don't know the drag characteristics of my
(modified) plane yet. The effectiveness of my IVO adjustable prop at high
altitude (20K') is still unknown.
I guess what I'm saying is that I think I'm "in the ballpark" with my setup, but
I need to do more testing to be sure. IMHO, a T-04 turbo would be a large turbo
for a 13B which would probably work very well at higher altitudes, but will
probably require a large wastegate at lower altitudes to avoid overboosting. I
have a 5 psi spring in my wastegate and it starts relieving about 3,500 rpm
under load. I t/o at 4,500 rpm and that's about 200 hp based upon fuel flow. I
could set the boost to the max available which is about 15 psi which would be
about 400 hp at sea level, but I'd create other problems if I did that
(overheating, engine longevity, detonation, gearbox loads, etc). I think Paul
Yaws numbers for the turbo 13B are a good indication of what is possible. You
may want to talk to him, as he's the expert.
Good luck.
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