MJD
Posts: 1509
Joined: 5/27/2003
From: Orangeville,
ON, CANADA
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quote:
ORIGINAL: GrahamC
I subscribe to a Yahoo group called "049 collectors". There was an interesting post today about a proposed test to compare Castor to Synthetic oil in our 1/2a engines. Copied and pasted below is the original email plus my response.
I don't have any sure starts let alone new ones. If I had I would donate them to the cause.
I posted this here as there are those who read this forum who have these same questions and may be able and willing to lend a hand in support of this initative.
His name is Aaron and it appears he works for Novak Performance (car guys) and uses the email of novakperformance @ yahoo.com
quote:
Aaron,
I think this is great idea and if I had 2 new unrun surestarts I would donate them to the cause.
There is much in the way of old wives tales about the pluses, minuses, and virtues of castor oil versus synthetics and even about the need for these engines to use high nitro fuels (ie 25+%) but lets leave the variable of hi nitro out of the equation as after all you intend to only try and measure the difference between two types of oil.
I would suggest a third combination - a 50/50 blend of castor and synthetic. And this could be taken even further with 25/75 and 75/25 blends but lets not get carried away.
As to props, a 6x3 is as good as any and should represent a "decent load" on the engines under test. My preferred prop for 1/2a sport flying is the APC 5.7x3 or the APC 6x2 as I think the 6x3 is a wee bit much. However, just pick one and go for it.
Also, before even starting to break in the engines, tear them down (as I am sure have already planned), give them a good cleaning and ensure the piston ball joint is properly set before running the engines.
You might also consider replacing the Cox plugs with Galbreath heads and Nelson plugs. This should not have any impact on the results but reduce ensure consistencly between the engines and would let you save the Cox plugs for anytime you really need the Cox plugs.
I have taken the liberty of posting your proposal in the 1/2a forum on RcUniverse. There are many there who would be very interested in your results and you may find donors for the engines needed for the test.
cheers, Graham in Ottawa Canada
At 04:28 5/15/2008 -0000, you wrote:
>Good Day,
> My name is Aaron Novak, been watching this group for a bit and grew
>up flying 1/2A CL airplanes. Now I work in engineering as a "big"
>engine company. Ive always read the disputes between synthetic and
>castor oils in our small engines, but never saw any kind of
>scientific testing. So I have a proposal:
>
>2-Identical new COX surestart engines
>1-run on 25% Nitro 25% Castor oil fuel (Bakers AA)
>1-run on 25% Nitro 25% Synthetic oil fuel (Cool Power Blue)
>Fuels to be accurately blended by myself from virgin materials.
>Engines run side by side with 32oz fuel tanks propped with 6-3 APC
>props ( balanced ). Engines will be broken in for 30 minutes using
>the intended endurance fuel using the standard rich-lean-rich
>procedure. Both engines will be run 25-50 rpm rich of peak and
>allowed to run the entire endurance of the 32 oz tank. Peak RPM will
>be recorded at the beginning and end of the run to check for any
>loss of performance. The engines will then be torn down and a full
>inspection for wear done and pictures of the parts taken for all to
>view and posted in this group. I would also entertain a
>castor/synthetic blend depending on the results.
>
>Is this something anyone would be interested in?? If so I am willing
>to donate the time, facility, fuel ingredients and all if someone
>can donate the engines.
>
>Thanks!!
>-Aaron Novak
>
Seems like a good cause in need of a couple of "cheap" surestarts to get it going.
So what say ye Denizens of this corner of World 1/2a ?
cheers, Graham
- For $6.99 a pop. why doesn't he just order two, wouldn't that be easier than trying to score two on the forums? Or is that deal no longer available?
- 25% oil? I would say run less than that - who runs 25% synthetic in 1/2A's? Nobody, and few run 25% castor unless they blend or juggle their own fuels.
20% oil might be a more representative test. Otherwise, results could be skewed by the disproportionate amount of oil.
- If a castor/synthetic blend is going to be tested, I would recommend one of the more common blends on the market - say 80/20 syn/cas? An additional test that would be of real practical value is to run one on 32oz of off the shelf regular old syn/cas sport fuel, i.e. 18% total oil 80:20 syn/cas blend, compared to the two above fuels. It would be a useful data point to know the relative wear rate. This way, one would know more about the sin or virtue level of using those fuels.
- One thing I would say is that in normal operation they either get launched on the rich side then go comfortably lean towards the end of the tank, or they get tweaked a little closer to peak and run like gangbusters until the end of the tank when they go a bit too lean. How much difference that type of cycling will make versus pure endurance testing at near peak, I dunno. Comments?
In terms of pure longetivity of the piston/cylinder and ball joint, I guess this will tell a fair bit.
Alan @ Weston UK says he's run a TD .049 flat out on (Weston's..) Prosynth fuel with much less oil than we would normally consider .049-worthy, and recorded lower cylinder head temps and better peak rpm than with traditional fuel. Then again, he also said that the factory team has has had West .50 powered Magnums flying at 240mph. At least one of the above two claims is bogus..  . If I am not mistaken (and I easily could be) cylinder head temp doesn't really tell the story about wear rate that one might think anyways.
MJD
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The Great Castor vs Synthetic debate - 
