running a straight pipe on a 1/4 scale,Will R?
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running a straight pipe on a 1/4 scale,Will R?
today the pipe coupler split on my 1/4 scale buggy and for a lil' while i just ran the 5' header. it seems to add power like it want to rev out instantly! why do i even have to run my 'tuned pipe"? Will Robinson if your read'in i'm running 5%syn,5% poly, and 15%nitro now...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
Mike:
The "Tuned pipes" that are easily available usually aren't tuned that well if at all, and have a greater function as mufflers than as a performance enhancement. Often an open pipe will give better power, but a lot more noise also. Looks like your 5" (I assume 5' was a typo) is just about the right length for your set up. If you can get away with the noise there's no reason to put the expansion chamber back on. Except the possible preservation of your hearing.
On the fuel. Do you really need 5% oil with that engine? It wont hurt, but I thought you could go to 3%, or even 2% and still be safe.
Bill.
The "Tuned pipes" that are easily available usually aren't tuned that well if at all, and have a greater function as mufflers than as a performance enhancement. Often an open pipe will give better power, but a lot more noise also. Looks like your 5" (I assume 5' was a typo) is just about the right length for your set up. If you can get away with the noise there's no reason to put the expansion chamber back on. Except the possible preservation of your hearing.
On the fuel. Do you really need 5% oil with that engine? It wont hurt, but I thought you could go to 3%, or even 2% and still be safe.
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
i ran it again today and it's just too loud! my ears were ringin. it's kill'in me because i had no idea of the untaped power- free power at that. i guess i'll put the pipe back on and slide it up the header a lil to make it shorter. maybe that will help some.
i went with the 5% syn. for no other reason than i like a lil smoke trail when i drive. plus wont the added oil pull some of the heat out of the motor though the exhaust?...PB
i went with the 5% syn. for no other reason than i like a lil smoke trail when i drive. plus wont the added oil pull some of the heat out of the motor though the exhaust?...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
Mike:
The synthetic leaves a smoke trail of burned oil. It's not effective as a cooling agent. Castor oil leaves a trail of unburnt oil, and it does carry heat away from the engine.
Regardless, up to the point of fouling the spark plug more oil wont hurt, whether it's synthetic or castor.
And on the other. If you feel like some experimentation, the expanding taper acts like an infinitely variable length of header pipe, between the length to the start of the taper and the end. So if the head pipe is 5", and there is a one inch section before the taper starts, your effective short length is six inches. Then if the opening tapered section is another six inches, you have a pipe that has most of the characteristics of a 12" pipe at low rpm, and working its way with increasing rpm to being an effective 6" length at high rpm. That's what you would have if you cut the pipe apart at its largest diameter. But when you use the complete pipe, the reversed cone section also comes into play, as does the stinger on the end.
So, as I said, if you feel like doing some experimentation, you can shorten the head pipe a little at a time, you might well find the power coming back without the increased noise level. You will reach a point where the power isn't increasing any more, that means it's time to stop. Or you might find the power down from the last attempt, if you save the cut bits you can weld the last one back on, or buy a new head pipe and cut it to the length you found worked best.
It is also possible the ideal length will be longer than what you now have, so if you have some short pieces of matching pipe start with two couplers and some added length, work your way down to what you now have before cutting the pipe on the engine.
Problem: The peak length will change as the air temperature and humidity change, so unless you keep a selection of different length head pipes it will always (almost) be a compromise.
Enjoy.
Bill.
The synthetic leaves a smoke trail of burned oil. It's not effective as a cooling agent. Castor oil leaves a trail of unburnt oil, and it does carry heat away from the engine.
Regardless, up to the point of fouling the spark plug more oil wont hurt, whether it's synthetic or castor.
And on the other. If you feel like some experimentation, the expanding taper acts like an infinitely variable length of header pipe, between the length to the start of the taper and the end. So if the head pipe is 5", and there is a one inch section before the taper starts, your effective short length is six inches. Then if the opening tapered section is another six inches, you have a pipe that has most of the characteristics of a 12" pipe at low rpm, and working its way with increasing rpm to being an effective 6" length at high rpm. That's what you would have if you cut the pipe apart at its largest diameter. But when you use the complete pipe, the reversed cone section also comes into play, as does the stinger on the end.
So, as I said, if you feel like doing some experimentation, you can shorten the head pipe a little at a time, you might well find the power coming back without the increased noise level. You will reach a point where the power isn't increasing any more, that means it's time to stop. Or you might find the power down from the last attempt, if you save the cut bits you can weld the last one back on, or buy a new head pipe and cut it to the length you found worked best.
It is also possible the ideal length will be longer than what you now have, so if you have some short pieces of matching pipe start with two couplers and some added length, work your way down to what you now have before cutting the pipe on the engine.
Problem: The peak length will change as the air temperature and humidity change, so unless you keep a selection of different length head pipes it will always (almost) be a compromise.
Enjoy.
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
thanks much for your insight bill, as always. i think i'll try cutting it down a lil' with the ol' pipe cuter. it's too long anyway in my opinion. but do i realy have to cut it? can i get the same results just by 'sliding' it farther up the header? also i have seen mufflers made to fit on the stinger end of the pipe. do you know of one available that will fit over the end of just the header?...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
Mike:
If sliding the expansion chamber up the pipe shortens its length rather than just having it stick further inside it will work to change the tuning.
But another thought - do a search on "Mousse can," That might be a good way to go since you already have the head pipe at a good length.
Exhaust (and intake) tuning is not specific to cars, model planes, or motorcycles. But when you get down to items specific to a model car I am out of it. Can't tell you anything about what is available just for them. Point me to an item I'll look at it, might even go out on a limb and offer an opinion.
Bill.
If sliding the expansion chamber up the pipe shortens its length rather than just having it stick further inside it will work to change the tuning.
But another thought - do a search on "Mousse can," That might be a good way to go since you already have the head pipe at a good length.
Exhaust (and intake) tuning is not specific to cars, model planes, or motorcycles. But when you get down to items specific to a model car I am out of it. Can't tell you anything about what is available just for them. Point me to an item I'll look at it, might even go out on a limb and offer an opinion.
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
i checked out the mousse can and that looks like good ol' grass roots r/c'in to me[sm=thumbup.gif]. i think i'm just run the header and an adapted 'stinger muffler' they claim that it doesn't take away hardly any power but still mufflels the sound. heres a link www.davesmotors.com/store/product465.html tell what you think. will it be the same power wise from having to taper down the header so it can fit? thanks for lookin...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
Mike:
Tapering the head pipe will change the tuning. Best if you can get a muffler to fit the existing pipe diameter. Might not have a great effect, though.
But a mousse can is $29 less expensive than the muffler you pointed to. Go ahead and do the mousse can bit, you'll find it does a pretty good job as a muffler too. If you don't get what you want you can always go back and buy the muffler.
Bill.
Tapering the head pipe will change the tuning. Best if you can get a muffler to fit the existing pipe diameter. Might not have a great effect, though.
But a mousse can is $29 less expensive than the muffler you pointed to. Go ahead and do the mousse can bit, you'll find it does a pretty good job as a muffler too. If you don't get what you want you can always go back and buy the muffler.
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
ok i did some searching and reading and everything i've seen says the mousse can is said to work on small motors .12 through .25. what size approx. would i need for a 27cc motor?
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RE: running a straight pipe on a 1/4 scale,Will R?
Paul:
Now there you might have a problem I didn't think about. There aren't too many large aluminum cans around that would be strong enough. One I have found is used by a company named "Raw Spirit." If you have a liquor store around that caters to the "Yuppie" crowd, you might find their brand of cocktails. The cans are 12 ounce (355ml) and should be big enough, if just barely. Whether they are big enough or not, buy a six pack and you can have a good time emptying them. The one I have I found on the side of the road. (Right... you say) There might also be something in a larger can available.
Since you're running a car weight wont be as much a consideration as it is on a plane, so you're not really limited to aluminum cans. You could try a steel can, something like a propane torch bottle, but do be careful cutting the first hole.
The larger the can, the smaller diameter the outlet can be, and the better the muffling.
If you figure the volume of the expansion chamber you took off, that will most likely be your minimum size.
Keep me informed.
Bill.
Now there you might have a problem I didn't think about. There aren't too many large aluminum cans around that would be strong enough. One I have found is used by a company named "Raw Spirit." If you have a liquor store around that caters to the "Yuppie" crowd, you might find their brand of cocktails. The cans are 12 ounce (355ml) and should be big enough, if just barely. Whether they are big enough or not, buy a six pack and you can have a good time emptying them. The one I have I found on the side of the road. (Right... you say) There might also be something in a larger can available.
Since you're running a car weight wont be as much a consideration as it is on a plane, so you're not really limited to aluminum cans. You could try a steel can, something like a propane torch bottle, but do be careful cutting the first hole.
The larger the can, the smaller diameter the outlet can be, and the better the muffling.
If you figure the volume of the expansion chamber you took off, that will most likely be your minimum size.
Keep me informed.
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
heres what i made already and woefully too small, 7oz.
the next problem is my header is not very long so the can has to have some kinda taper to fit in the space between the shock and the rear bulkhead. i'll let you know how the first pipe runs...PB
the next problem is my header is not very long so the can has to have some kinda taper to fit in the space between the shock and the rear bulkhead. i'll let you know how the first pipe runs...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
Pauly:
Looks awfully tight to get through there. Would it be possible to run the exhaust over the bulkhead? Or run it forward?
Bill.
Looks awfully tight to get through there. Would it be possible to run the exhaust over the bulkhead? Or run it forward?
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
the first pipe was not good[&o]. far too small! heres my second go round. it's 14oz. i can and will mount it facing forward. it's raining out so maybe tomorrow we will see how it does. p.s. hows the weather down there? were gettin a couple of inches up here...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
update: the second pipe is where the power is! very close to no pipe at all plus less noise. it's too big though and facing forward there is no support for it. i bored out the end of the lil pipe so we will see. hopefully that will help. any idea on how i can strip off the lettering and stuff?...PB
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RE: running a straight pipe on a 1/4 scale,Will R?
Paul:
The easiest way to get the paint off would be burn it off with a torch, be careful not to melt the can. Second, experiment with various solvents until you find one that works, and scrub it off. Least pleasant would be sanding it.
Or you could just paint over it.
Bill.
The easiest way to get the paint off would be burn it off with a torch, be careful not to melt the can. Second, experiment with various solvents until you find one that works, and scrub it off. Least pleasant would be sanding it.
Or you could just paint over it.
Bill.
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RE: running a straight pipe on a 1/4 scale,Will R?
the lil' bored out pipe is golden! it has all the power i'm lookin for. it's a bit loud but not like no pipe at all. i tried taking a butane torch to get the paint off it to no avail. maybe some kind of stripper will work. thanks for all your help...PB