Today's Message Index:
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1. 06:58 AM - Stump the Stars- RV-8 Engine Questions (Don.Alexander@AstenJohnson.com)
2. 08:16 AM - What's the difference? (Randy Richter)
3. 10:32 AM - Re: Stump the Stars- RV-8 Engine Questions (James R. Cunningham)
4. 09:58 PM - Re: Stump the Stars- RV-8 Engine Questions (flyseaplane)
Message 1
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| Subject: | Stump the Stars- RV-8 Engine Questions |
08/28/2003 09:54:39 AM
--> Engines-List message posted by: Don.Alexander@AstenJohnson.com
I am building a RV-8 and am considering an Aerosport Power (Bart) 360
cubic inch engine. I will run auto fuel on occasion and am considering
stepping the compression ratio down to 7.5-1 in order to move further away
from any potential detonation issue. Aerosport is guessing that I will end
up with around 170 HP with this ratio and say that they can do it with no
problem. I have spoken to other RV folks that run the normal 8.5-1
180/200hp on auto fuel with no reported problems (yet) other than some
vapor lock issues that can be solved with care in designing the fuel
system. They all report that an occasional load of 100 LL is run through
the engine to help the valves.
OK- here goes...I am looking for opinions so let's hear them:
1) Am I on the right course, or am I going to miss the 10 or so HP that I
am going to sacrifice by going to the lower compression set-up?
2) I asked about the benefit of porting/flow balancing the engine, and
they didn't think that I would get much benefit out of it with the 7.5-1
jugs. Is there any reason to pursue this, and what might I gain by doing
so?
3) I am going with dual Lightspeed ignition systems (with dual electrical
system backup).
4) Carbureted for simplicity and weight savings.
5) Whirlwind 150 series CS prop. I may have to revisit this choice as
there are concerns about using the electronic ignition with this prop. I
think that the earlier 150 series may have had issues with spinner
bulkheads cracking from the resonance, but Whirlwind may have fixed this
already. This is a very light 3-blade prop and I am wondering if I will
have a rough-running engine at slow speeds because of this, or if the
Lightspeed unit will retard the timing enough to smooth things out a bit at
lower RPM's.
6) Engine break-in- Aerosport will test-run the engine on a stand long
enough to make sure that everything is ok. I would like for them to put a
few hard hours on it (for an upcharge, of course) to allow the rings to set
a bit. I am very concerned about dealing with the first flight and having
to also break in the engine at the same time and thought that Aerosport
could help me out by doing this in a controlled manner with a load-prop
while on the stand. Any thoughts?
Thanks in advance
Don
Do not archive
Message 2
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| Subject: | What's the difference? |
--> Engines-List message posted by: Randy Richter <richterrbb@earthlink.net>
All,
I'm the FNG on the list and really find (most) of the submissions to
this list very informative. That's why I'm soliciting your advice.
I plan to start building an RV-7A sometime in the next 6-18 months (I've
been activated in the Air Force and don't know when I'll be de-mobilized
yet). I want aerobatic capability and understand that this requires, for
example, a Lyc IO-360-Axxx engine. My questions are these: What's the
difference between parallel valve and angle valve? How does this affect
the appearance of the airplane (I really don't like that little scoop on
the underside of most cowls!)? Is the IO-360-A1B6 (200 HP) suitable?
What are your experiences installing/maintaining your engines?
Many thanks for your inputs!
Randy Richter
Message 3
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| Subject: | Re: Stump the Stars- RV-8 Engine Questions |
--> Engines-List message posted by: "James R. Cunningham" <jrccea@bellsouth.net>
This is not a recommendation to go either way. There is an STC for
running autogas with 8.5 pistons in certified O-320's.
You might also consider putting a 100 capsule aspirin tablet bottle full
(remove the aspirin first) of Pennsoil 2 cycle ashless synthetic
outboard motor oil in each 5 to 6 gallons of fuel to help the valves.
Message 4
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| Subject: | Re: Stump the Stars- RV-8 Engine Questions |
--> Engines-List message posted by: "flyseaplane" <flyseaplane@netzero.net>
From: "James R. Cunningham" <jrccea@bellsouth.net>
"You might also consider putting a 100 capsule aspirin tablet bottle full
(remove the aspirin first) of Pennsoil 2 cycle ashless synthetic outboard
motor oil in each 5 to 6 gallons of fuel to help the valves."
++++++++++++++
James, do you have any proof that this works??
I have heard of almost EVERYTHING that people swear works.
2-cycle oil, Auto trans fluid, Marvel Mystery oil, etc. etc. etc. etc.
None of these lubricate at the temperatures that the exhaust seats see. They
just turn to carbon at high temps, which doesn't help lubricate the valves
at all. Tetraethyl lead is the only thing I have heard of that actually
works. I know the "lead substitutes" that you buy at wal-mart don't work,
and I have the burned valves to prove it.
OH yeah, some of you all are going to say "but it is ashless". Yeah, put
some ashless oil in a spoon and hold it over a blowtorch. It still turns to
carbon.
take care all,
Linc
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