tuned pipe for O.S. 46VX-M ?
10-10-2007, 09:34 PM
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RE: tuned pipe for O.S. 46VX-M ?
hello guys on my old ops it ran best 10 1/8 from the plug to the center of the fatest part of the pipe running 40 % and head clearance was set at .016 thousands of a inch. and thanks fast9 for looking into this for me
10-11-2007, 10:54 AM
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RE: tuned pipe for O.S. 46VX-M ?
Sorry but I have not been by the place where I keep my boats in a few days, I should be able to check on that length today. I am by no means some sort of expert, but I've run a number of boats. Usually, the engine manufacturer will give you a rough pipe length to start with. I usually start about an inch longer to be safe. If they give you a range start with the longest length. The pipe maker will probably have an estimated range also. If it seems to run really good, (after it is broken in and the mixture is close) I will cut about 1/4 " at a time. If it seems to not rev out well or is difficult to get on the pipe I might take a 1/2" off the first time. If I think I am getting close I might cut about 1/8" at a time. I quit as soon as I can not see any performance increase. It's time consuming, and to do it right the engine must be broken in, the mixture set close and about the right prop on the boat. I just use a hack say and a file and cut it at the pond.
10-11-2007, 11:48 AM
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RE: tuned pipe for O.S. 46VX-M ?
Fast9...I've checked with the OS website regarding the right pipe and the correct length, but to no avail. It's difficult to get any meaningful feedback on this issue or any other from those folks. They have not been helpful at all! I guess all I can do is adopt your method of cutting a little at a time until I feel I'm at the right point. Seems like there ought to be a more precise method, but what the hey. I can't find it. Thanks for your feedback. I appreciate it.
10-11-2007, 03:18 PM
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RE: tuned pipe for O.S. 46VX-M ?
Gentlemen, I believe i've solved the tuned pipe mystery[8D]:
I've just received my new engine and in the instructions it clearly states:
ANY OF THE TUNED SILENCER CURRENTLY AVAILABLE FOR .65 TO .90 cu.in.ENGINES MAY BE USED.
that leaves any of the .40 tuned pipe OUT! reading further, this just might be the reason why
:
WHEN A TUNED SILENCER IS SET TO BE TUNED BEST AT FULL THROTTLE, THE ENGINE WILL NOT GET OUT OF TUNE AND KEEP RUNNING AT HIGH R.P.M. WHEN CLOSE THE THROTTLE FROM FULL THROTTLE TO REDUCE THE SPEED FOR A TURN, WHILE THE MIXTURE GETS LEAN TO THE DEGREE OF THROTTLE CLOSING. THIS MAY CAUSE CONNECTING ROD SEIZURE WHICH WILL RESULT IN CONNECTING ROD FAILURE!
now if translated to better English this is what they're saying:
when you close partially the throttle while "on pipe" the engine continues on high revs BUT by cutting the throttle you starve the fuel to engine THUS it overheats!
further on, they propose a remedy (for this NOT to happen):
A) (IN A TURN) CLOSE THE THROTTLE TO IDLE JUST LONG ENOUGH TO GET IT "OFF THE PIPE" AND IMMEDIATELY REOPEN THE THROTTLE TO THE DESIRED POSITION FOR THE TURN
B) SET THE TUNED PIPE A LITTLE LONGER TO ALLOW FOR THE ENGINE TO "GET OUT OF TUNE" EASILY WHEN THE THROTTLE IS MOVED FROM THE FULL THROTTLE POSITION
there you go! so as long as the engine DOES NOT STAY on the pipe when throtteling back it looks to be safe!
so Pete i wouldn't cut the pipe at all as long as the engine gets "on the pipe" at full throttle[8D]
I hope this solves the mystery,
Cheers, Vasek
I've just received my new engine and in the instructions it clearly states:
ANY OF THE TUNED SILENCER CURRENTLY AVAILABLE FOR .65 TO .90 cu.in.ENGINES MAY BE USED.
that leaves any of the .40 tuned pipe OUT! reading further, this just might be the reason why
:WHEN A TUNED SILENCER IS SET TO BE TUNED BEST AT FULL THROTTLE, THE ENGINE WILL NOT GET OUT OF TUNE AND KEEP RUNNING AT HIGH R.P.M. WHEN CLOSE THE THROTTLE FROM FULL THROTTLE TO REDUCE THE SPEED FOR A TURN, WHILE THE MIXTURE GETS LEAN TO THE DEGREE OF THROTTLE CLOSING. THIS MAY CAUSE CONNECTING ROD SEIZURE WHICH WILL RESULT IN CONNECTING ROD FAILURE!
now if translated to better English this is what they're saying:
when you close partially the throttle while "on pipe" the engine continues on high revs BUT by cutting the throttle you starve the fuel to engine THUS it overheats!
further on, they propose a remedy (for this NOT to happen):
A) (IN A TURN) CLOSE THE THROTTLE TO IDLE JUST LONG ENOUGH TO GET IT "OFF THE PIPE" AND IMMEDIATELY REOPEN THE THROTTLE TO THE DESIRED POSITION FOR THE TURN
B) SET THE TUNED PIPE A LITTLE LONGER TO ALLOW FOR THE ENGINE TO "GET OUT OF TUNE" EASILY WHEN THE THROTTLE IS MOVED FROM THE FULL THROTTLE POSITION
there you go! so as long as the engine DOES NOT STAY on the pipe when throtteling back it looks to be safe!
so Pete i wouldn't cut the pipe at all as long as the engine gets "on the pipe" at full throttle[8D]
I hope this solves the mystery,
Cheers, Vasek
10-11-2007, 07:17 PM
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RE: tuned pipe for O.S. 46VX-M ?
ORIGINAL: Getnoff
Fast9.....how do you figure out exactly what the "right" pipe length measurement should be? I have always heard that you're suppose to measure from the glow plug down the header and pipe to the fattest part of the tuned pipe...BUT...what is the right measurement for any engine pipe combination? Do you just cut a little at a time off the tuned pipe until the engine performance is what you're looking for, and how do you know that you've gotten to that point? What exactly are you looking for? Please help.
I went on the net trying to research this, and Oh my God! I came across one of the mot technical write-ups that I've ever read, and quote frankly, it was beyond my mental capability to comprehend. There must be a "Tuned Pipe for Dummies" write-up out there somewhere, but I haven't found it. Is there an easy way for us "newbies" to grasp this? If so, PLEASE share it!
Fast9.....how do you figure out exactly what the "right" pipe length measurement should be? I have always heard that you're suppose to measure from the glow plug down the header and pipe to the fattest part of the tuned pipe...BUT...what is the right measurement for any engine pipe combination? Do you just cut a little at a time off the tuned pipe until the engine performance is what you're looking for, and how do you know that you've gotten to that point? What exactly are you looking for? Please help.
I went on the net trying to research this, and Oh my God! I came across one of the mot technical write-ups that I've ever read, and quote frankly, it was beyond my mental capability to comprehend. There must be a "Tuned Pipe for Dummies" write-up out there somewhere, but I haven't found it. Is there an easy way for us "newbies" to grasp this? If so, PLEASE share it!
Have a look here at an article by Gary Baldwin, South African racer of FSRV.
For circuit racing set up but the practical set up is the same wherever you are running.
Regards,
Glenn
10-11-2007, 07:23 PM
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RE: tuned pipe for O.S. 46VX-M ?
ORIGINAL: vasek
Gentlemen, I believe i've solved the tuned pipe mystery[8D]:
I've just received my new engine and in the instructions it clearly states:
ANY OF THE TUNED SILENCER CURRENTLY AVAILABLE FOR .65 TO .90 cu.in.ENGINES MAY BE USED.
that leaves any of the .40 tuned pipe OUT! reading further, this just might be the reason why:
WHEN A TUNED SILENCER IS SET TO BE TUNED BEST AT FULL THROTTLE, THE ENGINE WILL NOT GET OUT OF TUNE AND KEEP RUNNING AT HIGH R.P.M. WHEN CLOSE THE THROTTLE FROM FULL THROTTLE TO REDUCE THE SPEED FOR A TURN, WHILE THE MIXTURE GETS LEAN TO THE DEGREE OF THROTTLE CLOSING. THIS MAY CAUSE CONNECTING ROD SEIZURE WHICH WILL RESULT IN CONNECTING ROD FAILURE!
now if translated to better English this is what they're saying:
when you close partially the throttle while "on pipe" the engine continues on high revs BUT by cutting the throttle you starve the fuel to engine THUS it overheats!
further on, they propose a remedy (for this NOT to happen):
A) (IN A TURN) CLOSE THE THROTTLE TO IDLE JUST LONG ENOUGH TO GET IT "OFF THE PIPE" AND IMMEDIATELY REOPEN THE THROTTLE TO THE DESIRED POSITION FOR THE TURN
B) SET THE TUNED PIPE A LITTLE LONGER TO ALLOW FOR THE ENGINE TO "GET OUT OF TUNE" EASILY WHEN THE THROTTLE IS MOVED FROM THE FULL THROTTLE POSITION
there you go! so as long as the engine DOES NOT STAY on the pipe when throtteling back it looks to be safe!
so Pete i wouldn't cut the pipe at all as long as the engine gets "on the pipe" at full throttle[8D]
I hope this solves the mystery,
Cheers, Vasek
Gentlemen, I believe i've solved the tuned pipe mystery[8D]:
I've just received my new engine and in the instructions it clearly states:
ANY OF THE TUNED SILENCER CURRENTLY AVAILABLE FOR .65 TO .90 cu.in.ENGINES MAY BE USED.
that leaves any of the .40 tuned pipe OUT! reading further, this just might be the reason why
:WHEN A TUNED SILENCER IS SET TO BE TUNED BEST AT FULL THROTTLE, THE ENGINE WILL NOT GET OUT OF TUNE AND KEEP RUNNING AT HIGH R.P.M. WHEN CLOSE THE THROTTLE FROM FULL THROTTLE TO REDUCE THE SPEED FOR A TURN, WHILE THE MIXTURE GETS LEAN TO THE DEGREE OF THROTTLE CLOSING. THIS MAY CAUSE CONNECTING ROD SEIZURE WHICH WILL RESULT IN CONNECTING ROD FAILURE!
now if translated to better English this is what they're saying:
when you close partially the throttle while "on pipe" the engine continues on high revs BUT by cutting the throttle you starve the fuel to engine THUS it overheats!
further on, they propose a remedy (for this NOT to happen):
A) (IN A TURN) CLOSE THE THROTTLE TO IDLE JUST LONG ENOUGH TO GET IT "OFF THE PIPE" AND IMMEDIATELY REOPEN THE THROTTLE TO THE DESIRED POSITION FOR THE TURN
B) SET THE TUNED PIPE A LITTLE LONGER TO ALLOW FOR THE ENGINE TO "GET OUT OF TUNE" EASILY WHEN THE THROTTLE IS MOVED FROM THE FULL THROTTLE POSITION
there you go! so as long as the engine DOES NOT STAY on the pipe when throtteling back it looks to be safe!
so Pete i wouldn't cut the pipe at all as long as the engine gets "on the pipe" at full throttle[8D]
I hope this solves the mystery,
Cheers, Vasek
Kind of see what you are saying Vasek, but, the whole idea of a nitro engine and tuned pipe is high performance - have always tuned pipes to give overall best compromise for the course being run on, it's my experience that when the throttle is closed the revs drop pretty quick, on any engine.
As the fuel contains the lubricant then naturally there is a period of lubrication deficiency. It's is and always has been the case with two stroke motors.
Good quality fuel with the correct lubricant content for boats should overcome this issue and maintain sufficient lubricant for what are, lets face it, the very brief moments when the throttle is closed on a nitro engine.
I just can not see a pipe causing this issue.
Glenn
10-11-2007, 09:02 PM
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RE: tuned pipe for O.S. 46VX-M ?
This is all very interesting feedback. Whether or not valid. I at least now know why OS is giving this warning about which size tuned pipe to run with their .46 VX-M. As I think about it, wouldn't this concern by OS ultimately apply to every single 2-stoke nitro engine out there? Why don't we see this warning made by all manufacturers? Does OS put this warning on all of their engines? I'm feeling more and more confident now about just running a .45 sized tuned pipe with this engine. I bought a new CMDI 45XTS and a MACs muffled and unmuffled 11cc pipe. Personally, I just think I'll start with the .45, and see what happens.
10-12-2007, 02:33 AM
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RE: tuned pipe for O.S. 46VX-M ?
ORIGINAL: glennb2006
Just don't shut the throttle!!
Easy.
Glenn
Just don't shut the throttle!!
Easy.
Glenn
[&:]that's why i opt for the recommendation (B) to use the longer (.60 size) pipe
cheers V.
10-12-2007, 11:09 AM
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RE: tuned pipe for O.S. 46VX-M ?
Yeah. I second that. I've got 4 of these OS .46 VX-M's...2 new and 2 used. Don't ask me why, but I do. To date I've only run 1 of them and that was with a Macs 1369 muffled pipe mounted aboard a Cajun Bullet 45 hull. It ran okay, but I wasn't jumping with joy, and that's why I've been so interested in this thread.
10-12-2007, 09:07 PM
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RE: tuned pipe for O.S. 46VX-M ?
Hello again,
well, I only have certain experience gained over many years.
To me, it makes little sense what is written in the OS data sheets.
There is one optimum tuned pipe for any given engine operating in certain conditions, and the tuned length is of course adjustable for different props, nitro content, hulls, atmospheric conditions etc.
Ultimately, the pipe is always tuned to give the best power compromise (Lap times) achievable - or at least it should be.
It seems to me, from reading back in this thread, that there is a consensus to run a pipe for a larger motor with this engine, again, it does not seem to add up to me, the power will be produced at lower than optimum RPM. Unless maybe that is what OS are trying to achieve for some reason - people running their engines tuned to produce maximum power at lower revs. than is achievable.
Just a thought.
Regards,
Glenn
well, I only have certain experience gained over many years.
To me, it makes little sense what is written in the OS data sheets.
There is one optimum tuned pipe for any given engine operating in certain conditions, and the tuned length is of course adjustable for different props, nitro content, hulls, atmospheric conditions etc.
Ultimately, the pipe is always tuned to give the best power compromise (Lap times) achievable - or at least it should be.
It seems to me, from reading back in this thread, that there is a consensus to run a pipe for a larger motor with this engine, again, it does not seem to add up to me, the power will be produced at lower than optimum RPM. Unless maybe that is what OS are trying to achieve for some reason - people running their engines tuned to produce maximum power at lower revs. than is achievable.
Just a thought.
Regards,
Glenn
10-14-2007, 04:06 PM
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RE: tuned pipe for O.S. 46VX-M ?
ORIGINAL: wave waker
i have a goodluck on this combination OS.46, silent pipe and prather 245 on tc31 hull.
btw, what hull r u goin to run?
i have a goodluck on this combination OS.46, silent pipe and prather 245 on tc31 hull.
btw, what hull r u goin to run?
Sean
10-14-2007, 04:28 PM
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RE: tuned pipe for O.S. 46VX-M ?
here's a better view of the pipe, the one in cylindrical shape, i believed it's called silent pipe .45- .60 by irwin or copper pipe..hope somebody's familiar with this will chine in.
10-14-2007, 11:42 PM
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RE: tuned pipe for O.S. 46VX-M ?
ORIGINAL: wave waker
btw, what hull r u goin to run?
btw, what hull r u goin to run?
]
10-15-2007, 05:16 PM
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RE: tuned pipe for O.S. 46VX-M ?
Back on the issue of pipe length. Mine is at 11". (5" form cylinder center to end of header and another six of pipe). I am probably running a hair rich and I have a 3" piece of silicone tube after the pipe to get the exhaust out the back(not sure how this affects the pipe tune).
As far as the engine not coming off the pipe, mine comes on and off in an instant. I joke with my friends it should be a drag boat because it will go from idle to 50 mph in about 100 ft. I do have an OPS motor in another boat that does tend to hang on to the pipe for maybe a half second after you lift. It's a little annoying, but I never considered it a real issue with hurting the motor. Maybe I need to try a longer pipe on it.
As far as the engine not coming off the pipe, mine comes on and off in an instant. I joke with my friends it should be a drag boat because it will go from idle to 50 mph in about 100 ft. I do have an OPS motor in another boat that does tend to hang on to the pipe for maybe a half second after you lift. It's a little annoying, but I never considered it a real issue with hurting the motor. Maybe I need to try a longer pipe on it.
10-16-2007, 02:13 AM
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RE: tuned pipe for O.S. 46VX-M ?
Fas9, that's good new with the OPS .40 tuned pipe. I just bought one used off of e*bay
i might also get a .60 size Macs from TH and try both
i might also get a .60 size Macs from TH and try both
10-16-2007, 08:33 PM
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RE: tuned pipe for O.S. 46VX-M ?
thanks fast 9 for the info on pipe length i should have my header next weekend so i just may get to get it in the water before the ice forms up here
thanks again for your help
thanks again for your help
10-16-2007, 08:40 PM
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RE: tuned pipe for O.S. 46VX-M ?
thanks fast 9 for the info on pipe length i should have my header next weekend so i just may get to get it in the water before the ice forms up here
thanks again for your help
thanks again for your help
