Fox .15 Fuel?

Is Fox Super Fuel, 5% Nitro, 29% Caster ok for a Fox .15 size engine?
I figure it is better safe to ask rather then assume.

Thanks
Paul

rootbeard,
Duke Fox used to recommend "Missile Mist".
I think any good fuel with 15%-25% nitro and 22% 25% lube should work well. If it is a well-used engine I would suggest all castor.
I think the Fox 35 is the only Fox that NEEDS 25%-29% mostly or all castor.
Duke used to recommend Superfuel for worn out engines (iron/steel) also. It will restore some compression.
Sorry for rambling.

Sig 10%-15% nitro 25% all castor, or similar. (15% nitro preferred)

Bill <><

Sig Champion 10% seems to make my motors happy.

(No idea about the oil contents though)

How about Fox Formula-15 15% Nitro/18% Castor

http://www.foxmanufacturing.com/store/shop.cfm?currpage=2&cat=Fuel

Thanks
Paul

>How about Fox Formula-15 15% Nitro/18% Castor
>
>http://www.foxmanufacturing.com/store/shop.cfm?currpage=2&cat=Fuel
>
For a "newish" 15, after break-in, that would probably be fine, but for its starting hour, and its old age, more oil is in order, and the older it gets, the closer to 100% castor you want to go (as the compression goes down, the castor should go up, somewhat compensating for the wear). I would use no less than 22% oil during a small engine's breakin runs.

And in my book, 15's or less in displacement are "small".

.

Kiwi

>Is Fox Super Fuel, 5% Nitro, 29% Caster ok for a Fox .15
>size engine?

You failed to state which engine you are talking about.

For the slant plug engine and others with the iron piston/sleeve the answer is absolutely yes, but a higher nitro would be better.

For the BB schneurle engines 22% oil would be good, for an ABC engine all synthethic will be OK but a blend with 5-50% castor will work well.

If you use all synthetic and don't fly the engine on a regular basis you will need to use a good after-run oil especially with a ball bearing engine. With all/high castor and plain bearings it is a good practice but not required

I will try to look closer at the engine when I get home tonight. All I know is it is a used Fox .15

Any other sources for fuel other then Fox and Sig?
LHS is not a option for me. It is a R/C car shop. The guys know very little about planes and carry very little inventory for planes. C/L is almost null.

Thanks
Paul

Be careful of car fuels. They run at high RPM and usually can tolerate less oil. If you do need to use one of these fuels add enough castor oil to bring it up to 22%-25% total oil.
As far as I know ALL Fox .15's are iron/steel piston/cylinders.

> As far as I know ALL Fox .15's are iron/steel piston/cylinders.
>
The BB-shaft one will tolerate lower oil percentage levels more readily than a plain-bushing front end type. The seriously different aspect on most Fox engines is that they can suffer from rust problems faster if an all-synthetic oil fuel is used. Among the products of burning fuel is water, and synthetic oils don't protect the engines like castor does, and as a metter of fact, it also breaks down and leaves water behind when it gets moderately hot.

.

Kiwi

I have been searching the past post. I know someone posted that there is a place that will custom mix what ever you need.
Anyone have that link?
I do find it hard that I can not find Fox fuel for a Fox engine???

Thanks
Paul

Since you are in Tennessee check with Red Max in South Carolina. They custom blend but don't know about a minimum. (800-742-8484) See pg 42 of May Model Aviation.

Powermaster fuel has (or had) a fuel with 28/29% castor (512-285-9595)

Ritch's Hobbies will blend to your specs, no minimum, (713-661-5458)

LAST EDITED ON Apr-01-04 AT 11:48 AM (CDT)
 
>Since you are in Tennessee check with Red Max in South Carolina. They custom blend but don't
>know about a minimum. (800-742-8484) See pg 42 of May Model Aviation.
>
>Powermaster fuel has (or had) a fuel with 28/29% castor (512-285-9595)
>
>Ritch's Hobbies will blend to your specs, no minimum, (713-661-5458)

Avoid Red Max when a fuel mix needs to have REAL, decent castor. They use a totally inferior type and then claim otherwise. Their lies about castor have cost them the trust of a large part of the CL community. Powermaster *is* good stuff, so is Ritch's Brew. I don't know what arrangements either one has any more, if any, for saving the user from paying huge hazmat shipping fees/penalties.

.

Kiwi

>I have been searching the past post. I know someone posted
>that there is a place that will custom mix what ever you
>need.
>Anyone have that link?
>I do find it hard that I can not find Fox fuel for a Fox
>engine???
>
>Thanks
>Paul
>

This may or may not help you but the past thread enclosed has been helpfull for me.

Steve Helmick
Charter Member
2323 posts Jul-10-03, 11:54 AM (CDT)
 
2. "RE: fuel question"
In response to message #1
 
   Here's a formula for deriving oil needed to boost fuel from % of oil present to % of oil wanted
Where:
C= % of oil current
X= oz. of oil added
Y= % of oil desired
all measurements in oz.
and figured for 1 gallon fuel (128 oz.)

128Y - 128C = X - XY

Solved for 20% oil to 28% oil
128(.28) - 128(.20) = X - .28X
35.84 - 25.6 = .72X
10.24 = .72X
14.222 = X

You need to add 14.222 oz. to move 20% oil to 28% oil.

Nitro reduction formula where
C = %Nitro present
X = still equals added oz. of oil
R = reduced Nitro %
R = 128 * C / 128 + X
with the 20% to 28% change and 10% nitro fuel
R = 128(.10) / (128 + 14.222)
R = 12.8 / 142.222
R = .090001sumptin or 9% nitro
These formulas work with any percentage of nitro or oil. As long as you know where you are, you can get where you want to go. I might add that if you are looking to boost nitro, just use the first formula for nitro instead of oil, be careful though, you will lower oil content when you add nitro. I snatched this off RCOnline CL forum several years ago. Steve

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Mike Gretz
unregistered user
Jul-10-03, 03:48 PM (CDT)
 
3. "RE: fuel question"
In response to message #2
 
   Altering fuel is actually a bit tricky. Depends on just how accurate you want to be. Here's your example:

You're starting with "a gallon of fuel, 10% nitro, 20% castor oil".
Here's the breakdown of what's actually in that gallon:
Note: 1 gallon = 128 total fld.oz.
nitro - 12.8 fld.oz. - 10% (of 128 total oz.)
oil - 25.6 fld.oz. - 20% (of 128 total oz.)
methanol - 89.6 fld.oz. - 70% (of 128 total oz.)

If you add 14.222 fld.oz. of oil, as Steve says, you will then have a total of 142.222 fld.oz. of fuel (128 plus 14.222)
The breakdown will be:
nitro - 12.8 fld.oz. - 9%
oil - 39.822 fld.oz. - 28%
methanol - 89.6 fld.oz. - 63%

So now you have the 28% oil you want, but your nitro percentage is down to 9%.

The answer is to take your base gallon of fuel and add 14.9 oz. of oil AND add 1.7 oz. of nitro.
You will end up with 144.6 oz. of new fuel that will be:
nitro - 14.5 fld.oz. - 10%
oil - 40.5 fld.oz. - 28%
methanol - 89.6 fld.oz. - 62%

LAST EDITED ON Mar-31-04 AT 08:41 PM (CDT)
 
>> As far as I know ALL Fox .15's are iron/steel piston/cylinders.
>>
>The BB-shaft one will tolerate lower oil percentage levels
>more readily than a plain-bushing front end type. The
>seriously different aspect on most Fox engines is that they
>can suffer from rust problems faster if an all-synthetic oil
>fuel is used. Among the products of burning fuel is water,
>and synthetic oils don't protect the engines like castor
>does, and as a metter of fact, it also breaks down and
>leaves water behind when it gets moderately hot.
>
>.
>
>Kiwi
>
>**

It ain't the bearings or the piston and sleeve that is the weak point on these but the con rod. Just like a stock OS Max .35S, it is the cast aluminum rod that you have to watch out for. These need all castor and more the better- otherwise you are asking for trouble.
GMA once told me that the first thing you do with one of these puppies (assuming you have the parts) is pull the rod and replace it with one of the forged .15XX issues- makes 'em darn near bulletproof.

Jake

LAST EDITED ON Apr-01-04 AT 09:54 AM (CDT)
 
I will take all the castor I can get.
I just wish I could order a Qt bottle off the shelf with the right mixture for this engine.

Thanks
Paul

rootbeard: If you are talking about the late 50s-early 60s Steel Fin or slant plug monoblock 15...

I approach these small Foxes as if they are 1/2As. They like nitro, where 15% is a nice amount. Also, you don't need the 29% oil like Fox recommends for the 35 Stunt. 25% is sufficient, and maybe even a bit less.

In chilly 40 to 50 degree weather, these engines want to be heated up some. So, use the nitro. In hot, 90 degree+ temps, you probably could run the 29% oil 5 % nitro mix with no difficulty.

Another point: an 8-4 seems to hit a sweet spot for stunt/sport aps with these engines. In fact, the instruction manual was very specific in this recommendation.