[FlyRotary] Re: turbo math
I am planing to put a turbo on my
coot and I plan to install a huge waist gate that will be used a a
dump valve to shut the turbo down, also on the intake side I will have
a bypass flapper valve that will let cool fresh air in when the turbo
is shut down, most bigger turbo setups have these incase of a turbo
failure.
With this setup you can have your
cake and eat it to, use the turbo when you need it but for economy
cruise your better off without it and your not putting unnecessary
ware and tare on the turbo, also a great safety factor as you will be
coming down if you ever lose a turbo and with this just kick it in
bypass mode.
All of this shouldn't take up much
space either.
Interesting idea, but here are some things to
consider.
You
will probably need a muffler if you bypass the turbo. This isn't
a negative if you planned to have one anyway, though you certainly
don't need a muffler with a stock turbo and manifold. I have
to figure that you're talking about using aftermarket stuff here,
and you may very well need a
muffler anyway.
Bypassing the turbo will help with some failure modes,
but not all. Any sort of failure on the compressor
side side of the turbo will send broken pieces of metal through
the engine before you can shut it down. An intercooler will
probably catch the bigger pieces, but it'll be game over if you
trash the rotors. If you use a filter, I don't
think this will be a very likely failure mode. I'm betting that
most damaged compressor blades come from ingesting objects, which
would be bad even without the turbo. Of course I have no
filter or intercooler, so I guess I'm SOL.
I'm
not sure how much wear and tear will be saved on the turbo. A
good turbo will run a long time before you wear it out. I really
think that's the least of our problems.
I
can't argue with the idea of saving some fuel at economy cruise
power settings, but for me, it wouldn't be worth the trouble of
installing the redundant exhaust and bypass. I'm guessing that
you're planning to use a part time turbo for takeoff, instead
of NOS?
Cheers,
Rusty
(not a turbo expert)
Yes that's the plan to eliminate the NOS and use the turbo
at high ALT where the air is cool.
I have many years experience drag racing a turbo VW bug
running on alcohol pushing 100 inches manifold pressure and have had
many turbo failures but have never seen a failure of the intake
blades, most were from throwing the tips off the exhaust turbine which
only made for turbo lag and surprisingly just a slight drop in boost
on the top end.
The most common problem was bearing seizure which was like
stuffing a potato up the intake and tail pipe and for this the bypass
mode would save you, also I had carbon seals fail which would lay out
a hell of a big smoke screen and would empty the crank case in a
hurry, for this I am going to have a shutoff valve on the oil into the
turbo so that if my low oil buzzer and light goes off and I look back
and see a smoke screen I will put the turbo in bypass mode and shut
the oil down to it.
Still have the old turbo bug but haven't run it in 8 years
as I have an airplane to fly now.
Ken Welter
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