Today's Message Index:
----------------------
1. 04:50 AM - Re: (Trampas)
2. 05:08 AM - Re: V-8 Airplane power. (John Mireley)
3. 06:07 AM - V8's with crank-mounted props (Gary Casey)
4. 09:28 PM - Engine source. (Dean Psiropoulos)
Message 1
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--> Engines-List message posted by: "Trampas" <tstern@nc.rr.com>
I am sure that there are others on this list who are more qualified than
I am to address these problems but here is what I perceive the problems
with auto conversions to be.
The problem with bolting the prop directly to the crank of an auto
engine is that prop only likes to turn around 2000 RPM, while an auto
engine develops maximum horse power around 4500 RPM. Therefore most
automotive engines require a reduction drive of some sorts.
The thrust load of a prop is a concern. An Aircraft engine will have
thrust bearings designed to take the load, automotive engines also have
thrust bearings but due to the gearing problem above most people will
not bolt the prop directly to the crank any how, even though the
bearings may handle it. The gear reduction drives therefore must be
designed to handle the thrust loading of the prop. The different
manufactures handle this in different ways. For example one I know of
uses tapered roller bearings like front wheel bearings on a rear wheel
drive car.
One of the most important things in my opinion with an auto conversion
is to monitor the gear reduction drive bearing temperature, some use oil
in unit and monitor oil temperature. This is the best way to warn
against a possible failure of the bearings before they actually fail.
That is bearings normally fail by first having an increase in friction
which generates more heat, the heat increase and friction will then
combine to catastrophically break something.
The other thing to look at is the water pump on the engine. That is most
auto conversions will run the engine at 4000RPM for long period of
times. While in cars they run an average of 2000-2500 RPM. Thus you may
have premature water pump failure and possible cooling problems unless
you change the pulley on the water pump to reduce its speed. Personally
I wish there was a way to have dual water jackets for an engine. Humm
maybe that Cadillac north star engine...
Trampas
-----Original Message-----
From: owner-engines-list-server@matronics.com
[mailto:owner-engines-list-server@matronics.com] On Behalf Of Tedd
McHenry
Subject: Re: Engines-List:
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
> --> Engines-List message posted by: "Edward T. Jeffko"
<riovista@bossig.com>
>
> Tedd, I'm curious, what problems did Wittman's engines have?
I've heard a number of different stories over the years, but can't
corroborate
any of them. One is that the inverted installation resulted in cooling
problems. Another is that the original stub shaft to the prop failed,
but that
problem was supposedly solved with a larger-diameter shaft. There are
probably
people on this list with more detailed knowledge of it than I have.
I certainly like the idea of a bearing that takes all the non-torsional
prop
loads. But there are many, many examples of auto engines flying with a
prop
bolted directly to the stock crankshaft. I suspect that a wood prop
could be
successfully mounted that way on a lot of engines, but a heavier prop
might
present problems.
If I were going to hang a prop directly on the crankshaft of a Chevy, I
would
find out all I could about how it has worked on airboats. Just asking
around
won't do it, as this email thread has shown. You need to find the right
person
in the airboat community who's been around enough to know, and who
hasn't
formed his opinion haphazardly or purely from heresay. I'm sure there
are
people like that out there, you just have to find them.
Tedd McHenry
Surrey, BC
Message 2
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| Subject: | Re: V-8 Airplane power. |
--> Engines-List message posted by: John Mireley <mireley@msu.edu>
Dean Psiropoulos wrote:
>
> Now...the V-8 vendor for RVs is as follows:
>
> www.predatoraviation.com
>
This link doesn't work. Do you have one that does?
Message 3
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| Subject: | V8's with crank-mounted props |
--> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
Just for a couple of data points:
The main bearing diameter of a small-block Chevy 400 is the same as the
Lycoming IO-720.
I hear that airboats with aluminum props break cranks, but those with IVO
props don't.
Cadillac engines have larger diameter cranks and seem to break cranks less
in airboats.
Car engines are, of course, designed to handle gyroscopic loads. Consider a
20-pound flywheel spinning at 6,000 rpm. I searched some and couldn't find
a single example of a broken crank as a result of a crash (idea here is that
a race car is exposed to very large yaw rates during a crash and the engine
is likely spinning at a high rate during the event).
Conclusion: Bolting a lightweight prop to a car engine crank will not
likely result in a problem. Bolting an aluminum prop on might have some
risk.
Counterpoint: I heard Sean Tucker say that he overhauls his Lycoming every
300 hours primarily because he is likely to find cracks in the crankshaft.
I would avoid using an unproven crank/prop combination for aggressive
aerobatics.
Message 4
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--> Engines-List message posted by: "Dean Psiropoulos" <deanpsir@easystreet.com>
Speaking of engines, I'm looking for a good source for one of the new
Superior O-360 lycoming work-a-likes (I'd also like to hear from you folks
who've been flying the new Superior engines, I've heard good things from a
person I know who flew behind one). I have talked with Bart Lalond at
Aerosport power (Kamloops B.C. Canada) and was VERY impressed. That was
when I lived in Oregon and I now live in Florida so I'm wondering if a shop
with Aerosport's reputation can be found in the lower 48. Anyone have
suggestions? Thanks.
I didn't get any response from anyone yesterday when I posted this. Does
that mean everyone knows and uses engines from Aerosport power. Is there is
NO shop in the U.S. than can match his prices or customer service? WOW! RV
builders, is this true? Are you all using Bart's engines (or new Lycs from
Van's)? It wouldn't surprise me too much. Speak to me!! Thanks.
Dean Psiropoulos
RV-6A finish kit (finally)
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