Davis Diesel Conversion, anyone?

Santo Wiryaman

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Jun 25, 1991, 2:04:23 PM6/25/91

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Does anyone have experience with Davis Diesel Conversion Heads? I have
a Super Tigre X15 RC that I am thinking of converting to diesel. Recent
articles in RCM (Diesel F4) and in Model Aviation (Diesel Engines) spoke
favorably of diesels.

I am mainly interested in its quiet operation (so I was told). I mainly
fly 4-stroke for the same reason.

Robert Turner

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Jun 26, 1991, 3:14:52 PM6/26/91

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In article <1991Jun25.1...@pictel.uucp> sa...@pictel.uucp (Santo Wiryaman) writes:
>Does anyone have experience with Davis Diesel Conversion Heads? I have

I bought a Davis Diesel Head.

Up sides:

It is quieter than glow. Produces about the same amount of power, lower rpms
but bigger props. Diesels are as durable as two strokers in a crash, much
cheaper to repair than four strokers. Uses lots less fuel than two strokers,
about 50% of two stroker (longer flights for given tank).

Down sides:

Nobody knows how to teak the two knobs for the diesel. Glow engines only
have mixture. Diesels have mixture and compression and they work together.

Heads almost double the cost of a glow engine, but are usually cheaper than
four strokers. Might consider buying a PAW just to play with. PAWs are cheap
crummy diesels, but they offer some experience.

Fuel is not usually obtainable locally. Fuel cost a little more per once,
but you use less, but since Fuel cost is not a BIG issue with me, ???????

You can't use Windex to clean your plane. Must use a heavy duty grease
cutter to remove the kerosene. True Value hardware has a pink spray that works
real well.

Most models don't provide enough clearance for the big props diesels require.
A .25 size diesel should probably swing a 10x6. Put a 10x6 prop on an Eaglet
and you've only got about 1" of clearance. As a beginner I need as much prop
clearance as I can get.

Conversion carb's needle valve is to gross of the smaller fuel flows in diesels.
This makes setting the needle valve a little more sensitive than you might
be accustomed to.

You must use "gas" fuel tanks and line. Can't put diesel fuel in most tanks.
Causes the tanks to melt.

The exhaust smells different.

Robert

The perpetural beginner

--
Robert Turner (602) 897-5441 Semiconductor Systems Design Technology, Motorola
tur...@ssdt-tempe.sps.mot.com OR ...!uunet!dover!turner
"Most Americans do not know or appreciate the fact that citizenship is the
primary political office under a constitutional government." Mortimer Adler

as...@wombat.newcastle.edu.au

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Jun 28, 1991, 9:01:52 AM6/28/91

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In article <10...@nddsun1.sps.mot.com>, tur...@ssdt-tempe.sps.mot.com (Robert Turner) writes:
> In article <1991Jun25.1...@pictel.uucp> sa...@pictel.uucp (Santo Wiryaman) writes:
>>Does anyone have experience with Davis Diesel Conversion Heads? I have
>
> I bought a Davis Diesel Head.
>
> Up sides:
>
> It is quieter than glow. Produces about the same amount of power, lower rpms
> but bigger props. Diesels are as durable as two strokers in a crash, much
> cheaper to repair than four strokers. Uses lots less fuel than two strokers,
> about 50% of two stroker (longer flights for given tank).
>
>
> Down sides:
>
> Nobody knows how to teak the two knobs for the diesel. Glow engines only
> have mixture. Diesels have mixture and compression and they work together.
>
> Heads almost double the cost of a glow engine, but are usually cheaper than
> four strokers. Might consider buying a PAW just to play with. PAWs are cheap
> crummy diesels, but they offer some experience.

I think that this statement is a little extreme, I have a number of these
motors, and I regard them as excellent. Perhaps your admitted lack of experiencee
is clouding your vision.

Lyman Lew

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Jul 1, 1991, 4:07:39 PM7/1/91

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In article <1991Jun25.1...@pictel.uucp> sa...@pictel.uucp (Santo Wiryaman) writes:

>Does anyone have experience with Davis Diesel Conversion Heads? I have
>a Super Tigre X15 RC that I am thinking of converting to diesel. Recent
>articles in RCM (Diesel F4) and in Model Aviation (Diesel Engines) spoke
>favorably of diesels.
>
>I am mainly interested in its quiet operation (so I was told). I mainly
>fly 4-stroke for the same reason.
>
>-santo

I just ordered one over the phone this morning from Davis. I will be getting
the diesel head, fuel line, and two quarts of diesel fuel concentrate. It
should be here in a couple of weeks. The diesel head will be used on a KB
Sportster .45. The motor has been modified for rear exhast and has been
bench runned for about 15-20 minutes. It will turn a 10-6 prop at 12000
rpm on glow fuel. This is quite a bit slower than my Fox or Royal, but the
motor still needs more time before it reaches its peak. I will be testing
the KB in diesel and glow configuration to see what kind of output I can get
out of it. Davis told me I should use a 12-8 or 13-6 when the motor is
converted. He stated that the motor should turn about 9000 rpm on a 12-8.
This is gonna be interesting. Let me know if you guys are interested
in the outcome of my experiment.

Lyman Lew

____________________________________________________________________________
/ Lyman Lew l...@4ccvsh.asl.scg.hac.com
/ / Space and Communications Group Phone (213) 648-1964
/___/ Hughes Aircraft Company
/___ Bldg S21, MS E349, PO Box 92919, Los Angeles, CA 90009
____________________________________________________________________________

Robert Turner

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Jul 2, 1991, 12:24:36 PM7/2/91

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In article <15...@hacgate.UUCP> l...@4ccvw25.UUCP (Lyman Lew) writes:
>This is gonna be interesting. Let me know if you guys are interested
>in the outcome of my experiment.

Keep me posted!!

Robert