FAI fuel question

FAI fuel question
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> RC Fuels >> FAI fuel question

Page: [1]

Login

Message

<< Older Topic Newer Topic >>

FAI fuel question - 8/20/2004 2:29:53 PM

RoNeRiC

Posts: 183
Joined: 4/25/2004
From: East Moline, IL, USA
Status: offline

I'm going to get a new MVVS .49 engine. Needs 0-5% nitro. I bought 0% omega fuel which has 17% lube w/70syn 30 castor. I was reading the instructions and this forum about oil content. I want the total oil content to 20%. I'm looking at this to add to it http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXS622&P=0 . Now how much do I need to add to it to get to 20%, is this stuff ok, and since it is no nitro fuel will it still run ok without adding more methanol?

Another thing, if most engines require at least 18%, then why not make it with at least 18%. Like Omega is 17% oil content. Why 17%? Will not having that 1% be damaging to the engine?

Post #: 1

RE: FAI fuel question - 8/20/2004 2:36:03 PM

RoNeRiC

Posts: 183
Joined: 4/25/2004
From: East Moline, IL, USA
Status: offline

I was looking at the chart at klotzs website, is 4 oz the right answer, to bring 17% up to 20%? Measurement is for a gallon.

(in reply to RoNeRiC)

Post #: 2

RE: FAI fuel question - 8/21/2004 1:19:13 AM

downunder

Posts: 3113
Joined: 10/10/2002
From: Adelaide, AUSTRALIA
Status: offline

Let me try using these strange American ounces

1 gallon is 128 ounces and if the oil is 17% of this then there's 21.76 ounces of oil in there. If the content had been 20% oil then there'd be 25.6 ounces of oil so an extra 4 ounces would be near enough. But if you add 4 ounces then you end up with 132 ounces of fuel in total containing 25.76 (21.76 + 4) ounces of oil which gives 19.5% oil. Yes, I used a calculator to figure this out

If you use metrics it goes like this.
1 litre (1000cc) of fuel with 17% oil gives 170cc of oil. With 20% oil there's 200cc of oil so add 30cc and you're close. You don't need a calculator to work this out

(in reply to RoNeRiC)

Post #: 3

RE: FAI fuel question - 8/21/2004 2:32:29 AM

Ed Smith

Posts: 2807
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline

quote:

I was looking at the chart at klotzs website, is 4 oz the right answer, to bring 17% up to 20%? Measurement is for a gallon.

If the Klotz site says 4 oz why do you doubt it?

I find it rather amusing when people agonise over a 1% difference in oil content for say a $300.00 engine. Parked outside they probably have a$25,000.00 vehicle in which they drive to the sleaziest corner gas bar and fill it with the cheapest gas they can find!!

Ed S

(in reply to RoNeRiC)

Post #: 4

RE: FAI fuel question - 8/21/2004 4:01:43 AM

RoNeRiC

Posts: 183
Joined: 4/25/2004
From: East Moline, IL, USA
Status: offline

quote:

ORIGINAL: Ed Smith

quote:

I was looking at the chart at klotzs website, is 4 oz the right answer, to bring 17% up to 20%? Measurement is for a gallon.

If the Klotz site says 4 oz why do you doubt it?

I find it rather amusing when people agonise over a 1% difference in oil content for say a $300.00 engine. Parked outside they probably have a$25,000.00 vehicle in which they drive to the sleaziest corner gas bar and fill it with the cheapest gas they can find!!

Ed S

It doesn't say 4oz, I did the math of what they had on their percentage chart and that is what I came up with. Just wanted to see if I was right. Amazing that people answer threads with no advice at all.

< Message edited by RoNeRiC -- 8/21/2004 4:09:02 AM >

(in reply to Ed Smith)

Post #: 5

RE: FAI fuel question - 8/21/2004 4:05:19 AM

RoNeRiC

Posts: 183
Joined: 4/25/2004
From: East Moline, IL, USA
Status: offline

quote:

ORIGINAL: downunder

Let me try using these strange American ounces
1 gallon is 128 ounces and if the oil is 17% of this then there's 21.76 ounces of oil in there. If the content had been 20% oil then there'd be 25.6 ounces of oil so an extra 4 ounces would be near enough. But if you add 4 ounces then you end up with 132 ounces of fuel in total containing 25.76 (21.76 + 4) ounces of oil which gives 19.5% oil. Yes, I used a calculator to figure this out

If you use metrics it goes like this.
1 litre (1000cc) of fuel with 17% oil gives 170cc of oil. With 20% oil there's 200cc of oil so add 30cc and you're close. You don't need a calculator to work this out

So if I add the 4oz to a gallon of Omega,to bring it from 17% to 20%, will that effect my power output by throwing the percentage of Nitro/ methanol/oil?

(in reply to downunder)

Post #: 6

RE: FAI fuel question - 8/21/2004 8:53:00 AM

Ed Smith

Posts: 2807
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline

Ok, here is some advice. Because you will have reduced the percentage of the ingredient in the fuel that burns there will be a minimal decrease in performance. When I say minimal I mean so small that you will not be able to tell the difference. You would experience a bigger variation on different days of climate changes. Likewise the small amount of oil being added will not make much difference to the lubricating properties of the fuel, which at 17% is quite adequate. I have run high performance racing engines on high nitro fuel with 14% of all synthetic oil with no problems.

MVVS are robust quality built engines, small variations in oil or even other ingredients will make no discernible difference. Whatever fuel you will be using when operating this engine is the fuel you should be using for break-in.

Ed S

(in reply to RoNeRiC)

Post #: 7

RE: FAI fuel question - 8/21/2004 5:33:19 PM

RoNeRiC

Posts: 183
Joined: 4/25/2004
From: East Moline, IL, USA
Status: offline

quote:

ORIGINAL: Ed Smith

Ok, here is some advice. Because you will have reduced the percentage of the ingredient in the fuel that burns there will be a minimal decrease in performance. When I say minimal I mean so small that you will not be able to tell the difference. You would experience a bigger variation on different days of climate changes. Likewise the small amount of oil being added will not make much difference to the lubricating properties of the fuel, which at 17% is quite adequate. I have run high performance racing engines on high nitro fuel with 14% of all synthetic oil with no problems.

MVVS are robust quality built engines, small variations in oil or even other ingredients will make no discernible difference. Whatever fuel you will be using when operating this engine is the fuel you should be using for break-in.

Ed S

Thanks Ed. I can't wait until I fire that beast up!!!!

(in reply to Ed Smith)

Post #: 8

RE: FAI fuel question - 8/21/2004 7:04:49 PM

hauckf

Posts: 187
Joined: 3/1/2002
From: Decatur, AL, USA
Status: offline

To raise the oil percentage in a gallon of fuel from 17% to 20% add 4.8 ounces of oil to the gallon. If you want to calculate it yourself, here's the formula:

Fl oz. to add to a gallon = (D% -S%) X 128 / (100 - D%) where D% is the desired oil percentage, S% is the starting oil percentage. In your example, (20 - 17) X 128 / (100 - 20) = 4.8

Here's an easier way: If you are trying to raise the oil percentage of a gallon of fuel to 20% oil, add 1.6 oz. of oil for each percent of increase you want. In your case, you want to increase the percentage from 17 to 20, or 3%. 3 X 1.6 = 4.8 oz.

To get to 18% add 1.56 oz for each % increase you want.
To get to 19% add 1.58 oz for each % increase.
To get to 21% add 1.62 oz for each % increase.
To get to 22% add 1.64 oz for each % increase.

If you don't want to do any math at all, there are several sites that have calculators that will do the math for you, and several programs to do the calculations have been offered on this forum. (Sorry, I don't have any of the addressed for the sites.)

(in reply to RoNeRiC)

Post #: 9

RE: FAI fuel question - 8/22/2004 1:29:08 AM

downunder

Posts: 3113
Joined: 10/10/2002
From: Adelaide, AUSTRALIA
Status: offline

quote:

ORIGINAL: RoNeRiC
So if I add the 4oz to a gallon of Omega,to bring it from 17% to 20%, will that effect my power output by throwing the percentage of Nitro/ methanol/oil?

Adding some oil won't affect the power at all. The "fuel" part of fuel is just the methanol/nitro and the flow rate of this is what's set by the needle valve. If you add some oil then the needle just needs to be opened very slightly more (because now you're flowing slightly more oil) to get back to the same rate of methanol/nitro.

(in reply to RoNeRiC)

Post #: 10

RE: FAI fuel question - 9/19/2004 11:24:27 PM

kostask

Posts: 6
Joined: 6/23/2004
From: athens, GREECE
Status: offline

QUESTION:
ACCORDING TO KYOSHO THE STANDARD FUEL FOR THEIR STADIUM FORCE TRUCK IS 10% NITRO AND THE HIGH PERFORMANCE IS 16%,NOW I ASKED AT THE PLACE WHERE I BOUGHT MY R/C IF IT' S BETTER TO RUN THE TRUCK WITH FUEL HAVING 10% NITRO SO TO KEEP IT COOLER EVEN THOUGH IT WON'T BE AS FAST,AND THEY TOLD ME THAT THE MORE NITRO IN THE FUEL THE COLDER IT RUNS ... THAT DOESN 'T SEEM RIGHT THOUGH....A FRIEND TOLD ME THAT HE HAD BOUGHT BRAKE IN FUEL WHICH HAD NO NITRO IN IT AND THE ENGINE USED TO RUN REAL SWEAT..SO,ANYBODY HAVE ANY IDEA ABOUT THAT?
THANK YOU FOR YOUR TIME!

(in reply to downunder)

Post #: 11

RE: FAI fuel question - 9/24/2004 11:47:43 PM

Jim Schwagle

Posts: 556
Joined: 12/23/2002
From: Canyon Country, CA, USA
Status: offline

The higher the nitro content, the richer you need to run the engine, to get enough fuel for the air passing through the carb (higher nitro means less methanol per ounce of fuel). More fuel means more oil, leads to a little cooler running engine.

_____________________________

Three useless things for a pilot...Runway behind you...
Altitude above you...Fuel at home...

(in reply to kostask)

Post #: 12

RE: FAI fuel question - 9/29/2004 10:26:08 PM

Bax

Posts: 12028
Joined: 4/26/2002
From: Champaign, IL, USA
Status: offline

quote:

ORIGINAL: Jim Schwagle

The higher the nitro content, the richer you need to run the engine, to get enough fuel for the air passing through the carb (higher nitro means less methanol per ounce of fuel). More fuel means more oil, leads to a little cooler running engine.

Sorry, but I must disagree. More power = more heat. No way to get around that. The actual needle setting will change, but if you're getting a higher power output, the engine will run at a higher temperature.

_____________________________

Bill Baxter, Manager Hobby Services/Futaba Service/North America
3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
Service Phone: 217 398-0007
Email: hobbyservices@hobbico.com

(in reply to Jim Schwagle)

Post #: 13

RE: FAI fuel question - 10/13/2004 6:44:21 PM

sdavied

Posts: 112
Joined: 9/1/2002
From: Ellis, KS, USA
Status: offline

For any mathematicians out there, here is the derivation of the equation:

x = amount to add
S = (% oil in original fuel) / 100
D = (% oil desired) / 100
Ts = Total volume at start
Te = Total volume at end
(note: x and T must be in the same units of measure)

Te = Ts + x
Ts * S = volume of oil at start
Te * D = volume of oil at end

TeD = TsS + x
(Ts + x)D = TsS + x
DTs + Dx = TsS + x
DTs - TsS = x - Dx
DTs - TsS = x(1 - D)

[Ts(D - S)] / (1 - D)

This works with any system of measure (metric or US).

< Message edited by sdavied -- 10/13/2004 7:03:26 PM >

_____________________________

JR Ergo .30
O.S. .32 SX-H

(in reply to Bax)

Post #: 14

RE: FAI fuel question - 10/16/2004 8:44:21 PM

Jim Schwagle

Posts: 556
Joined: 12/23/2002
From: Canyon Country, CA, USA
Status: offline

All I can do is repeat what Dave Shadel said. With a higher nitro fuel, you richen it up, power output is similar, but with a richer mixture, you run cooler. Perhaps we are talking about two different things. With higher nitro, you run richer than normally. Yes, more nitro adds heat to the engine, but more oil helps remove it. I guess it just depends upon if you are trying to lean it for every RPM. Heli pilots will run on 30% fuel, but with 23% oil and I've seen the head cool enough to put your fingers on, but Helis tend to run richer than "plankers". It's all determined by where you leave that little old needle.

Edit for clarity.
Second edit for grammar....duh.

< Message edited by Jim Schwagle -- 10/16/2004 8:52:04 PM >

_____________________________

Three useless things for a pilot...Runway behind you...
Altitude above you...Fuel at home...

(in reply to sdavied)

Post #: 15

RE: FAI fuel question - 10/18/2004 9:38:16 PM