What head temps for gas? I need help.  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Gas Engines >> What head temps for gas? I need help.
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What head temps for gas? I need help. - 7/14/2008 10:15:14 PM   
quanta


 

Posts: 17
Joined: 8/22/2007
From: Ottawa, ON, CANADA
Status: offline 		Hi everyone,

I have an OS .50 Hyper ringed nitro engine that usually burns 15% or 30% nitro with I think around 22% oil content.

I am very interested in converting it to run on regular pump gas and oil mix. I have read so far the a ratio of 4:1 is good. It needs this high oil as it runs at 16000rpm continuously and without that kind of oil it would self destruct in short order. There is a fellow on these forums that started to do testing with these motors on gas but I have not seen any new posts from him recently. I am very keen to get mine running on gas.

I have a Carbsmart that has a sensor that is epoxied in the head. The control unit uses a servo to adjust the needle according to temp. So during hard loads it ends up richening the mixture during flight. It works perfect for nitro. The running temp is adjustable from 194f (90c) to 248f (120c).

I am hoping somebody can lead me in the right direction as to what temp a head should not pass in a motor like mine running gas/oil mix.

Thank you very much,

John
       Post #: 1

RE: What head temps for gas? I need help. - 7/14/2008 10:52:02 PM   
pe reivers



Posts: 2770
Joined: 1/23/2002
From: Arcen, , NETHERLANDS
Status: offline 		for gas, 150C is a good upper limit

_____________________________

Pe, Dealer for MVVS, MTW and Mejzlik; www.mvvs.nl
There is sanctuary in analisys.

(in reply to quanta)
       Post #: 2

RE: What head temps for gas? I need help. - 7/15/2008 1:46:32 AM   
JohnF


 

Posts: 307
Joined: 3/30/2003
From: toms river, NJ, USA
Status: offline 		John, where do I find a "carbsmart" and do you have any pictures you can post of the installation?

(in reply to pe reivers)
       Post #: 3

RE: What head temps for gas? I need help. - 7/15/2008 2:05:15 AM   
DMcQuinn



Posts: 1556
Joined: 1/9/2002
From: Chesterfield, MO, USA
Status: offline 		Pe - I have always appreciated your advice as it seems to well reasoned and scientific. What do you think of this information on the German 3W site where it says:

"Using this method the optimum temp. for air cooled two - stroke engines is approx. 220 - 270 degree Celsius".

Read the entire article here: http://www.3w-modellmotoren.com/english/3W_Modellmotoren.htm

They are measuring with a sensor mounted to a ring under the spark plug. This seems way too high to me.

(in reply to JohnF)
       Post #: 4

RE: What head temps for gas? I need help. - 7/15/2008 5:49:50 PM   
quanta


 

Posts: 17
Joined: 8/22/2007
From: Ottawa, ON, CANADA
Status: offline 		Hi, I get my parts from a good guy named Ken in Vancouver since I am in Canada. Great service and trust worthy. Here is the link the carbsmart parts.. http://www.rcflightstore.com/index.php?cPath=129&sort=3a&page=2

So if head temps of 150c are a good upper limit I will need to figure some thing out since it is only adjustable to 120 (or is it 130). The sensor is epoxy resined between two cooling fins as far in as possible to get it right up against the combustion chamber. This way it is quicker to sense temp differences and react accordingly to keep them close to the set temp. Works flawlessly on my OS50 hyper running nitro keeping perfect combustion temps and producing solid and safe power.

I will need to find an electronics guy and inquire about adding a resistor to trick the Carbsmart to allow it to sense 150 as 120. I don't think moving the sensor to another location further away from the combustion chamber is a good idea as it will not produce immediate results. Delaying it from richening the mixture and dropping the temp during a high temp situation is asking for trouble.

Does anyone know what percentage of power is produced by 30% nitro compared to a gas oil mix of 4:1 ?

Thanks again.


(in reply to DMcQuinn)
       Post #: 5

RE: What head temps for gas? I need help. - 7/15/2008 7:18:37 PM   
Truckracer


 

Posts: 562
Joined: 4/3/2004
From: Des Moines, IA, USA
Status: offline
quote:

ORIGINAL: quanta

Hi, I get my parts from a good guy named Ken in Vancouver since I am in Canada. Great service and trust worthy. Here is the link the carbsmart parts.. http://www.rcflightstore.com/index.php?cPath=129&sort=3a&page=2

So if head temps of 150c are a good upper limit I will need to figure some thing out since it is only adjustable to 120 (or is it 130). The sensor is epoxy resined between two cooling fins as far in as possible to get it right up against the combustion chamber. This way it is quicker to sense temp differences and react accordingly to keep them close to the set temp. Works flawlessly on my OS50 hyper running nitro keeping perfect combustion temps and producing solid and safe power.

I will need to find an electronics guy and inquire about adding a resistor to trick the Carbsmart to allow it to sense 150 as 120. I don't think moving the sensor to another location further away from the combustion chamber is a good idea as it will not produce immediate results. Delaying it from richening the mixture and dropping the temp during a high temp situation is asking for trouble.

Does anyone know what percentage of power is produced by 30% nitro compared to a gas oil mix of 4:1 ?

Thanks again.




Just curious quanta ....... what type of ignition are you going to use on your conversion and are you going to replace the stock carb with something more suitable for use with gas? Sounds like a very ambitious project.

(in reply to quanta)
       Post #: 6

RE: What head temps for gas? I need help. - 7/15/2008 9:05:03 PM   
pe reivers



Posts: 2770
Joined: 1/23/2002
From: Arcen, , NETHERLANDS
Status: offline 		Use the max temperature as is. With a good cooling system the mixture should richen up to a certain point, beyond which you dare not go with gas engines, or the plug will foul.
TIG! (This Is Gas!)
Being on the brink of four stroking rich at full throttle will be as far as you can go. Any richer, or you will have to replace plugs at an alarming rate. Hot plugs will help some if you want to go as far as that.

_____________________________

Pe, Dealer for MVVS, MTW and Mejzlik; www.mvvs.nl
There is sanctuary in analisys.

(in reply to quanta)
       Post #: 7

RE: What head temps for gas? I need help. - 7/16/2008 8:25:00 AM   
Ed Cregger



Posts: 7736
Joined: 1/31/2002
From: Ringgold, GA, USA
Status: offline
quote:

ORIGINAL: quanta

Hi everyone,

I have an OS .50 Hyper ringed nitro engine that usually burns 15% or 30% nitro with I think around 22% oil content.

I am very interested in converting it to run on regular pump gas and oil mix. I have read so far the a ratio of 4:1 is good. It needs this high oil as it runs at 16000rpm continuously and without that kind of oil it would self destruct in short order. There is a fellow on these forums that started to do testing with these motors on gas but I have not seen any new posts from him recently. I am very keen to get mine running on gas.

I have a Carbsmart that has a sensor that is epoxied in the head. The control unit uses a servo to adjust the needle according to temp. So during hard loads it ends up richening the mixture during flight. It works perfect for nitro. The running temp is adjustable from 194f (90c) to 248f (120c).

I am hoping somebody can lead me in the right direction as to what temp a head should not pass in a motor like mine running gas/oil mix.

Thank you very much,

John






The Carbsmart's function when running on a glow engine is to richen the mixture when temps elevate. This retards the timing - so to speak - but only in a glow engine. This function is next to useless with a spark fired gasoline/petrol engine.


Ed Cregger


_____________________________

Artisan

"Flying models since the Fifties - I'll get the hang of this yet!!!"

(in reply to quanta)
       Post #: 8

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