how important is that baffle
06-25-2006, 03:45 AM
#1
how important is that baffle
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
06-25-2006, 05:46 AM
#2
Senior Member
RE: how important is that baffle
I run all my twostrokes without baffles.Just make sure to readjust the needles,so the engine runs at optimum everytime you alter anything(baffle, siliconetubing...)
06-25-2006, 08:24 AM
#3
RE: how important is that baffle
ORIGINAL: asmund
I run all my twostrokes without baffles.Just make sure to readjust the needles,so the engine runs at optimum everytime you alter anything(baffle, siliconetubing...)
I run all my twostrokes without baffles.Just make sure to readjust the needles,so the engine runs at optimum everytime you alter anything(baffle, siliconetubing...)
Thanks Asmund, so I guess That you need some baffling to make the pressure fitting work with the hose to the tank. Its just strange that Now I get the !/2 tank dead sticks where as I didnt before the 8 inch silicone hose was on
06-25-2006, 10:48 AM
#4
RE: how important is that baffle
I'd suspect the long tubing added back some or most of the backpressure you lost by removing the baffle. Modern RC carbs are just too big to run without muffler pressure. Have a look at the size venturi in the old Fox (if you've still got it) and compare it to the size throat in the Magnum carb.
I just measured my old Fox 35 and it's 7mm (0.276") less the spray bar which looks like .125".
I just measured my old Fox 35 and it's 7mm (0.276") less the spray bar which looks like .125".
06-25-2006, 11:20 AM
#5
Senior Member
My Feedback: (14)
RE: how important is that baffle
ORIGINAL: suzonka
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
06-25-2006, 05:42 PM
#6
RE: how important is that baffle
ORIGINAL: Artisan
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
ORIGINAL: suzonka
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
06-25-2006, 06:08 PM
#7
RE: how important is that baffle
ORIGINAL: downunder
I'd suspect the long tubing added back some or most of the backpressure you lost by removing the baffle. Modern RC carbs are just too big to run without muffler pressure. Have a look at the size venturi in the old Fox (if you've still got it) and compare it to the size throat in the Magnum carb.
I just measured my old Fox 35 and it's 7mm (0.276") less the spray bar which looks like .125".
I'd suspect the long tubing added back some or most of the backpressure you lost by removing the baffle. Modern RC carbs are just too big to run without muffler pressure. Have a look at the size venturi in the old Fox (if you've still got it) and compare it to the size throat in the Magnum carb.
I just measured my old Fox 35 and it's 7mm (0.276") less the spray bar which looks like .125".
Yes your right downunder , May be Illhave to add more tubing to sorta ad pressure not to much sorta like a tuned exhaust,???
06-25-2006, 08:35 PM
#8
Senior Member
My Feedback: (14)
RE: how important is that baffle
ORIGINAL: suzonka
Yes Thanks for the info, and the Rossi is a very good engine
ORIGINAL: Artisan
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
ORIGINAL: suzonka
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
----------------
Sorry about that. I didn't answer your question. (blush)
It would depend upon which side of the baffle the pressure nipple is residing. If it is upstream, removing the baffle COULD reduce positive pressure to the fuel tank, therefore reducing fuel feed. If the pressure nipple is downstream of the baffle, I don't think it would make much difference.
06-25-2006, 11:09 PM
#9
RE: how important is that baffle
ORIGINAL: Artisan
----------------
Sorry about that. I didn't answer your question. (blush)
It would depend upon which side of the baffle the pressure nipple is residing. If it is upstream, removing the baffle COULD reduce positive pressure to the fuel tank, therefore reducing fuel feed. If the pressure nipple is downstream of the baffle, I don't think it would make much difference.
ORIGINAL: suzonka
Yes Thanks for the info, and the Rossi is a very good engine
ORIGINAL: Artisan
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
ORIGINAL: suzonka
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
How critical is the back pressure needed in r/c engine set ups like a 46 magnum BB ,I used to run my fox 35s without any mufflers in the old control line days and never a dead stick, But with my r/c ,s I get quit a few , here's what happened I took the baffle out of my 46 mag muffler and added a long silicone tubing ,maybe 8 inches, I had this set up on a plane for 2 years and no problems, now I put this very same engine in another model but didn't use the silicone tubing, so I get dead sticks now, on about 1/3rd to 1/2 tank full, so could it be it needs the baffle back in or the 8 inch tubing? any suggestions?
-------------
It depends.
Doncha hate answers like that?
The problem is that most manufacturers today have increased carb size (resulting in less negative pressure (suction) at the spray bar) to the point where they depend upon the pressure derived from the muffler in order to provide enough steady fuel flow to the carb for consistent operation.
Wanna do without muffler pressure at all? Fine, but you will have to reduce the carb air flow rate in order to do so. Yes, that's how the old control line engines were, they had small carburetors in order to provide the higher suction (negative pressure) that was necessary to pull the fuel reliably.
This is why I liked (and still do) Rossi engines. They obtain their extra power through superior design and execution, not through huge carbs that will not pull sufficient fuel unaided by muffler pressure.
----------------
Sorry about that. I didn't answer your question. (blush)
It would depend upon which side of the baffle the pressure nipple is residing. If it is upstream, removing the baffle COULD reduce positive pressure to the fuel tank, therefore reducing fuel feed. If the pressure nipple is downstream of the baffle, I don't think it would make much difference.
Thats a good answer , my nipple is before the baffle towards the exhaust port,so I would need the baffle,/Thanks Not to change the sibject, but I once had a new out of th4 box super tiger motor 40, I checked everything and broke it in right, well it went dead stick after 5 to 7 minutes of flying I sent it back they gave me another new motor , later on I found out some where on some site that some of them we made with the connecting rod turned around 180 deg from the way it was suppost to be, I dont know if mine had that sistuation, but the next one I got ran perfect from day one, and still is running ,so this dead stick stuff can really be nerve racking when you cant find the problem, Thanks again.
07-04-2006, 12:14 PM
#10
Senior Member
Join Date: Jun 2004
Location: Deep River, ON, CANADA
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RE: how important is that baffle
It very much depends on what brand & size engine you are using, plus what RPM you are pulling.
Some engines need the help from a baffle, while others don't care much.
For example, a TT 46 Pro runs really well with an 11-6 prop without a baffle (even with the muffler stinger drilled out), while a GMS 47 often improves in reliability by having a baffled muffler instead of the GMS tuned muffler.
Additionally, an engine that runs well without a baffle, with a particular prop, may run poorly unbaffled if you over-prop it & reduce the RPM significantly.
Conversely, a poor-running unbaffled engine may perk up dramatically by running a prop with less load, allowing the engine to wind up more.
Suck it and see.
Some engines need the help from a baffle, while others don't care much.
For example, a TT 46 Pro runs really well with an 11-6 prop without a baffle (even with the muffler stinger drilled out), while a GMS 47 often improves in reliability by having a baffled muffler instead of the GMS tuned muffler.
Additionally, an engine that runs well without a baffle, with a particular prop, may run poorly unbaffled if you over-prop it & reduce the RPM significantly.
Conversely, a poor-running unbaffled engine may perk up dramatically by running a prop with less load, allowing the engine to wind up more.
Suck it and see.
