How much oil to add?  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> RC Fuels >> How much oil to add?
Page: [1]

Login
Message << Older Topic   Newer Topic >>
How much oil to add? - 9/24/2002 6:14:31 PM   
LooneyTunes



Posts: 182
Joined: 6/12/2002
From: San Antonio, Texas
Status: offline 		I have an Enya 2 cycle engine that requires 20% oil minimum. I guess it has to do with the cast iron piston/ hardened steel liner. Unfortunately here in San Antonio TX the choices of fuels are limited. All I can find is the most common sport blends. Depending on the manufacturer, the oil content ranges from 16% to 18%. I would like to add some castor to one of these blends and end up with 20% + oil content.

I am mathematically 'challenged' and volumetric math was never my strong suit.

So, I was wondering if anyone could help me figure this out. I know that my nitro % will drop but I am not too worried about that. So, say I start with a gallon of 10% nitro and 18% oil. How much castor do I add to end up with 20% oil? Is there a formula I can use? Thank you in advance.
       Post #: 1

How much oil to add? - 9/24/2002 7:28:41 PM   
EdMan-RCU


 

Posts: 249
Joined: 3/5/2002
From: tallahassee, FL, USA
Status: offline 		LooneyTones,
Here's your answer!!
If you have 1 gal. of fuel (128oz.), at a current percent of oil at 18%, you will need to add [COLOR=red]3.2 oz [/COLOR] of oil to bring the percentage up to 20% total oil.

Good Luck & Happy Flyin'
EdMan

(in reply to LooneyTunes)
       Post #: 2

How much oil to add? - 9/24/2002 7:43:11 PM   
rajul



Posts: 6220
Joined: 6/18/2002
From: Missouri City, TX, USA
Status: offline 		I think it is important to define whether the 20% is meant to be volumetric % or weight %. Volumetric % may be a little more tricky to calculate as you need to know the specific gravity of each component. However, I guess that for small additions of oil, using weight % may be good enough. After all, how much accuracy do you need ? Good luck............

(in reply to LooneyTunes)
       Post #: 3

How much oil to add? - 9/25/2002 1:05:19 AM   
EdMan-RCU


 

Posts: 249
Joined: 3/5/2002
From: tallahassee, FL, USA
Status: offline 		I would believe the % is by volume as apposed by weight. There is a formula for the calculations I posted earlier.

EdMan

(in reply to LooneyTunes)
       Post #: 4

How much oil to add? - 9/25/2002 1:50:48 AM   
Sport_Pilot



Posts: 7651
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		<>

Actually the steel liner is not hardened, if both surfaces are hard it won't wear in. The piston is cast iron which is already very hard so the liner is made to be softer. That is why you must use 20%+ oil. It is not as hard as ABC or even a ringed engine sleeve.

(in reply to LooneyTunes)
       Post #: 5

How much oil to add? - 9/25/2002 5:19:25 PM   
Ed Smith


 

Posts: 2820
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		Now that is interesting. Cast iron is not considered a hard material. Every cast iron piston/steel liner engine I ever owned had a hardened steel liner. Is Enya doing something different?

Ed S

(in reply to LooneyTunes)
       Post #: 6

How much oil to add? - 9/25/2002 5:39:11 PM   
LooneyTunes



Posts: 182
Joined: 6/12/2002
From: San Antonio, Texas
Status: offline 		Thanks for all the help. I'll just add 4 fluid oz. I'd rather have more oil than not enough.

As far as the Enya piston/liner goes, I got this straight out of the owners pamphlet. The SS40 BB Enya has a cast iron piston and hardened steel liner. I guess most of the wear will happen on the piston since cast iron is softer than hardened steel. There really is not much 'wear-in' to speak of. I lubed the engine up and turned her over a few times. She is as smooth as silk. There is no 'pinch' like on a ABC engine. The Enya relies on precision fit of the parts. Not heat like a ABC engine. At least that is how I understand it.

(in reply to LooneyTunes)
       Post #: 7

How much oil to add? - 9/25/2002 5:42:25 PM   
Sport_Pilot



Posts: 7651
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		[QUOTE]Originally posted by Ed Smith
Now that is interesting. Cast iron is not considered a hard material. Every cast iron piston/steel liner engine I ever owned had a hardened steel liner. Is Enya doing something different?

Ed S [/QUOTE]

Wrong, Cast iron is considered a hard material, not as hard as hardened tool steel but much harder than mild steel. Cast iron has an excess of carbon, so much that pure carbon is found between the crystals of iron and other metals. More carbon the harder the metal. The globules of carbon is why cast iron goes clunk when you hit it with a hammer vs steel which will ring. During the time that most engines were lapped steel and iron many companies made their sleeves from leaded steel, one of the softer steel alloys, but they broke in easily and with lots of oil and little dirt would last a while. Enya, Fox, and other high quality engines used a harder steel that was a tad softer than the cast iron piston. Not hard enough for an engineer to call it a hardened steel liner (which technically they are not), but since it was harder than competition the manufactures could claim they were hard steel. If you ever wear one out you will see that the liner wears more than the piston.

(in reply to LooneyTunes)
       Post #: 8

How much oil to add? - 9/25/2002 10:18:19 PM   
Ed Smith


 

Posts: 2820
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		There are too many people on these Forums with big opinions and little knowledge.

I can only repeat what I said.

When I refer to hardened steel I am refering to steel that has gone through a heat treating process to through harden it. As were all of the steel liners I have ever owned.

A blanket statement like "More carbon the harder the metal" is incorrect. As was noted cast iron contains a lot of carbon. However the metal can be machined, cut and filed quite easily, hardly the characteristics of a hard metal.

I see that Looney Tunes has cleared up the matter. A cast iron piston and hardened steel liner. Sound familier?

I am finished with this thread.

Ed S

(in reply to LooneyTunes)
       Post #: 9

How much oil to add? - 9/25/2002 10:42:53 PM   
Sport_Pilot



Posts: 7651
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		Hardened steel is machinable also. I dispute that cast iron can be machined quite easily. It is hard to cut on a lathe for example requireing a more expensive metal than required for most steels, even unhardened tool steel. It also has a habit of cracking if you make too course of a cut. If you notice most machining of an engine block is ground not cut.

I have checked and I may have been wrong about the sleeve not being made of hardened steel, but many steels are softer even after hardenining, unless you are talking surface hardening which is what I think I got confused about. Check this out.

http://www.eltroservices.com/hardness.htm

You will find cast iron second to last and is harder than most steels.

(in reply to LooneyTunes)
       Post #: 10

How much oil to add? - 9/25/2002 11:00:43 PM   
Sport_Pilot



Posts: 7651
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		And another chart.

http://www.salemball.com/rockwell.htm

Note hardened 420 steel is softer than cast iron.

(in reply to LooneyTunes)
       Post #: 11

How much oil to add? - 9/26/2002 2:12:40 AM   
Steve Guinn



Posts: 835
Joined: 8/23/2002
From: WV
Status: offline 		The Byron lube booster has a mixing chart. It says to add 2.5 oz. of oil to go from 18 to 20%. Believe that works out to a 125 oz. gal.

_____________________________

"The weather is here, wish you were beautiful."
J. Buffett

(in reply to LooneyTunes)
       Post #: 12

How much oil to add? - 9/26/2002 5:29:02 AM   
hauckf


 

Posts: 188
Joined: 3/1/2002
From: Decatur, AL, USA
Status: offline 		Well, here we go again! EdMan's figure of 3.2 fluid oz. will increase 18% by volume to 20% by volume. Byron, however, calculates the percentages of the ingredients in their fuel by WEIGHT, not volume as do most other manufacturers. The differences are significant. 18% by weight of synthetic oil equates to about 15.5% by volume; 20% oil by weight is about 17.3% by volume (assuming a synthetic oil with a specific gravity of 1.000, 15% nitro). The Byron mixing chart is apparently meant to be used with their percent-by-weight fuels, and that is probably why their figure is 2.5 oz. instead of 3.2 oz. (A gallon contains 128 fluid oz.)

(in reply to LooneyTunes)
       Post #: 13

How much oil to add? - 9/26/2002 4:26:02 PM   
Ed Smith


 

Posts: 2820
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		We buy fuel by the gallon, not by the pound. Gallons and fluid ounces are volumes. Nitro is quite heavy. 15% by weight is less quantity than 15% by volume. Now they would not be trying to mislead us would they? Surely not!

Ed S

P.S. of course there could be some realy heavy oil. Think what that would do to the % by weight.

(in reply to LooneyTunes)
       Post #: 14

How much oil to add? - 9/26/2002 5:14:03 PM   
Sport_Pilot



Posts: 7651
Joined: 1/21/2002
From: Acworth, GA, USA
Status: offline 		Ed,

In doing some research I find it may be possible that some lapped steel engines had a harder liner than the piston. A poster on another site claims that US engines use a liner softer than the piston, and UK engines had a high chrome alloy sleeve that was harder than the cast iron piston. Also Cox engines use a chrome plated copper piston, the sleeve is steel and much softer. So maybe the Enya has a harder sleeve than the piston, and maybe not.

I cannot find anybody but you and Loonytunes who think that cast iron is a soft material!

So my strong opinion is not based on ignorance. Eh?

(in reply to LooneyTunes)