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Jack,
Having recently been operating TIO-540 J2BD (350Hp stock )
and TIO-540 AE2A (350Hp stock) and Turbo normalized IO-550s in a very
highly instrumented environment, I agree with almost all of your concerns.
BUT... let me note that you can get horsepower in different ways and
it turns out, there is a lot to be gained by HOW you get the horsepower and
a lot of problems can be avoided by being careful about HOW you get the
horsepower.
For example, I currently operate the TN-IO-550 engine at cruise at
approximately 260-265 Hp on a routine basis. After doing that for 800 hours
on a set of Millennium jugs, I tore down the engine (bottom end was at 1800
hours) and inspected the cylinders very very carefully. The cylinder
barrels were all within NEW limits (note, NOT just service limits, but new
limits) and this included the choke area! Valve guides etc were all in
excellent condition.
So... given your accurate observations about the traditional service
life of the TSIO-550 engines, how the heck did I do this?
Consider that the real problem is not the *MEAN* pressure in the
cylinders (mean pressure times displacement times RPM times a constant = Hp)
but the critical issue is the magnitude of the cylinder combustion pressure
at its peak value right after TDC when the piston is just starting down. It
is possible to make, say 350 Hp with the peak pressures at 1100 PSI and it
is also possible to make 350 HP with the peak pressures at only 950 PSI....
but with the mean pressures the same in each case. The difference in the
longevity and temperature issues for the engine are rather startling.
Using our PRISM (Pressure Reactive Intelligent Spark Management)
system we are able to do this almost effortlessly. I have been able to
operate these engines at 375 to 400 Hp with the peak cylinder pressures at
or below the values traditionally seen with the engines in the stock
configuration operating at 350 Hp.
So, yes, it is possible to develop these engines to deliver Hp up
in the 375 to 400 Hp range without grinding away on the jugs etc, all of
which have problems as you point out. And yes, you are very correct that
calibrating the Dyno is critical and it is easy to cheat on that. And your
concern about the durability issues are spot on.
Nevertheless, I do point out that we have demonstrated very good
success with very high continuous horsepower output (260-265) with all of
the CHTs held below 380F at altitude on hot days and we have done this for
extended intervals with almost no detectable wear on the critical mechanical
components. This capability has been reproduced on a number of engines that
are accumulating a lot of time at a very rapid rate right now with no
problems yet noted.
Regards, George Braly at GAMI
-----Original Message-----
From: Epijk@aol.com [mailto:Epijk@aol.com]
Sent: Friday, August 31, 2001 2:34 PM
To: lancair.list@olsusa.com
Subject: Re: TSIO550 Engine Modifications
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<< Lancair Builders' Mail List >>
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In a message dated 8/30/2001 8:23:08 PM Pacific Daylight Time,
AVIDWIZ@aol.com writes:
<< The benefit is increased horsepower (400 HP) and a smoother engine. >>
Just some thoughts to contemplate re the subject matter:
For the sake of discussion, lets conjecture that they REALLY CAN increase
the
power output to 400 HP. Since this is not a geared engine, they would
<SNIP>
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