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Old Jul 23, 2003, 03:01 AM
Boo
Guest
n/a Posts
Tuned pipe on a four stroke 120

Hi I asked this before but noone answered, idk if the post showed or not ?

Anyway, I've seen tuned pipes advertised for use with 4-stroke engines
and I wondered how much use they are ?

I know on a 2-stroke they improve breathing and power considerably but
I'd always assumed that with the separate intake and exhaust cycles on a
4-stroke there was no advantage to using a tuned pipe ?

If I am wrong here does anyone know what sort of power increase that eg
an OS 120 FS might expect from the addition of a full wave quiet pipe
like the ones Just Engines supply ?

Thanks,

--
Boo

Old Jul 23, 2003, 03:01 AM
Greg
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net>
wrote:

>Hi I asked this before but noone answered, idk if the post showed or not ?


It did, phone Just Engines and you're sure to get sound advice.

Greg
Old Jul 24, 2003, 03:01 AM
Boo
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

> phone Just Engines and you're sure to get sound advice.
>

This may be true but I just wondered what other modellers experience of
running 120 size (or similar) on tuned pipes was ? I mean are they hard
to set up, finicky on needle setting, peaky or what. Also how much
(if at all) does it affect the power output ?

I'm not dissing JE but they are in the market to sell stuff, I just
wondered what "real peoples" experiences were ?

Thanks,

--
Boo

Old Jul 24, 2003, 03:01 AM
Ed Cregger
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

Tuned pipes provide a boost in power for most two-strokes.

The only people running tuned pipes on four-strokes are those that are
saddled with strict noise restrictions.

While it is true that a divergent cone "can" provide some scavenging effect
for a four-stroke engine if tuned properly, I doubt that the whole tuned
pipe set-up is worth its weight unless noise reduction is figured into the
equation.

Ed Cregger




"Boo" <Boo@spam_me_no_spam.net> wrote in message
news:bfn7r5$5mp$1@newsg3.svr.pol.co.uk...
> > phone Just Engines and you're sure to get sound advice.
> >

> This may be true but I just wondered what other modellers experience of
> running 120 size (or similar) on tuned pipes was ? I mean are they hard
> to set up, finicky on needle setting, peaky or what. Also how much
> (if at all) does it affect the power output ?
>
> I'm not dissing JE but they are in the market to sell stuff, I just
> wondered what "real peoples" experiences were ?
>
> Thanks,
>
> --
> Boo
>




Old Jul 25, 2003, 03:00 AM
The Natural Philosopher
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

Boo wrote:

> > phone Just Engines and you're sure to get sound advice.

>
>>

> This may be true but I just wondered what other modellers experience of
> running 120 size (or similar) on tuned pipes was ? I mean are they hard
> to set up, finicky on needle setting, peaky or what. Also how much
> (if at all) does it affect the power output ?
>
> I'm not dissing JE but they are in the market to sell stuff, I just
> wondered what "real peoples" experiences were ?
>



Umm. A tuned pipe works, AFAICR, by using the fact that on a 2-stroke
teh exhaust and inlet effectively overlap, and teh tining dras unburnt
fule into the exhaust and then rams it back into the combustion chamber.

There is very little overlap on most 4-strokes, so I am dubious it would
actually make much difference in performance at all..certainly nothing
like as dramatic as on a 2-stroke that is desined to use it..

Get a turbocharger. That should work :-)




> Thanks,
>



Old Jul 25, 2003, 03:00 AM
The Natural Philosopher
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

Ed Cregger wrote:

> Tuned pipes provide a boost in power for most two-strokes.
>
> The only people running tuned pipes on four-strokes are those that are
> saddled with strict noise restrictions.
>
> While it is true that a divergent cone "can" provide some scavenging effect
> for a four-stroke engine if tuned properly, I doubt that the whole tuned
> pipe set-up is worth its weight unless noise reduction is figured into the
> equation.
>
> Ed Cregger



Thanks ed, that was my recollection as well. I am pretty sure that
racing 4 strokes do get some gain on tuned pipes in the car world, but
its not dramatic, and their valve timimgs are wild anyway.

AFAICR which confirms your opinon, its more about reducing exhaust back
pressure, than pre-chatging the combustion cyle - that is, on very high
gas flows, it makes teh silencing system look like less of an onstructin
than it otherwise might.

I am sure there should be a market for tiny turbochargers :-)



>
>
>
>
> "Boo" <Boo@spam_me_no_spam.net> wrote in message
> news:bfn7r5$5mp$1@newsg3.svr.pol.co.uk...
>
>>>phone Just Engines and you're sure to get sound advice.
>>>
>>>

>>This may be true but I just wondered what other modellers experience of
>>running 120 size (or similar) on tuned pipes was ? I mean are they hard
>>to set up, finicky on needle setting, peaky or what. Also how much
>>(if at all) does it affect the power output ?
>>
>>I'm not dissing JE but they are in the market to sell stuff, I just
>>wondered what "real peoples" experiences were ?
>>
>>Thanks,
>>
>>--
>>Boo
>>
>>

>
>
>



Old Jul 26, 2003, 03:01 AM
Bob Adkins
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net> wrote:

>Hi I asked this before but noone answered, idk if the post showed or not ?
>
>Anyway, I've seen tuned pipes advertised for use with 4-stroke engines
>and I wondered how much use they are ?
>
>I know on a 2-stroke they improve breathing and power considerably but
>I'd always assumed that with the separate intake and exhaust cycles on a
>4-stroke there was no advantage to using a tuned pipe ?
>
>If I am wrong here does anyone know what sort of power increase that eg
>an OS 120 FS might expect from the addition of a full wave quiet pipe
>like the ones Just Engines supply ?


I'm willing to bet that most 4 stroke pipes in use today are to route the
exhaust neatly through the belly pan, and to further silence the 4 stroke
sound.

Bob
Old Jul 26, 2003, 03:01 AM
Ed Cregger
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

I agree.

Any power gain, if it truly exists, is purely coincidental.

Ed Cregger


"Bob Adkins" <bobad@charter.net> wrote in message
news:k6b3iv0foge46f3mmgoimhe7tjsqlmiqrh@4ax.com...
> On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net> wrote:
>
> >Hi I asked this before but noone answered, idk if the post showed or not

?
> >
> >Anyway, I've seen tuned pipes advertised for use with 4-stroke engines
> >and I wondered how much use they are ?
> >
> >I know on a 2-stroke they improve breathing and power considerably but
> >I'd always assumed that with the separate intake and exhaust cycles on a
> >4-stroke there was no advantage to using a tuned pipe ?
> >
> >If I am wrong here does anyone know what sort of power increase that eg
> >an OS 120 FS might expect from the addition of a full wave quiet pipe
> >like the ones Just Engines supply ?

>
> I'm willing to bet that most 4 stroke pipes in use today are to route the
> exhaust neatly through the belly pan, and to further silence the 4 stroke
> sound.
>
> Bob




Old Jul 27, 2003, 03:00 AM
Courseyauto
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

Bob Adkins" <bobad@charter.net> wrote in message
news:k6b3iv0foge46f3mmgoimhe7tjsqlmiqrh@4ax.com...
> On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net> wrote:
>
> >Hi I asked this before but noone answered, idk if the post showed or not

?
> >
> >Anyway, I've seen tuned pipes advertised for use with 4-stroke engines
> >and I wondered how much use they are ?
> >
> >I know on a 2-stroke they improve breathing and power considerably but
> >I'd always assumed that with the separate intake and exhaust cycles on a
> >4-stroke there was no advantage to using a tuned pipe ?
> >
> >If I am wrong here does anyone know what sort of power increase that eg
> >an OS 120 FS might expect from the addition of a full wave quiet pipe
> >like the ones Just Engines supply ?

>
> I'm willing to bet that most 4 stroke pipes in use today are to route the
> exhaust neatly through the belly pan, and to further silence the 4 stroke
> sound.
>
> Bob



The only time a tune pipe would benifit on a 4 stroke is during the overlap
time that both valves are open at the same time,which varies with camshafts. it
is during this time that the exhaust would help pull intake charge into the
cylinder.
Old Jul 27, 2003, 03:00 AM
Icrashrc
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

Don't tell the top fuel and funny car guys [and gals] that tuned exhaust
doesn't work! Those may look like random pieces of pipe bolted on the head but
size and length are very critical.

>I agree.
>
>Any power gain, if it truly exists, is purely coincidental.
>
>Ed Cregger
>
>
>"Bob Adkins" <bobad@charter.net> wrote in message
>news:k6b3iv0foge46f3mmgoimhe7tjsqlmiqrh@4ax.com.. .
>> On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net> wrote:
>>
>> >Hi I asked this before but noone answered, idk if the post showed or not

>?
>> >
>> >Anyway, I've seen tuned pipes advertised for use with 4-stroke engines
>> >and I wondered how much use they are ?
>> >
>> >I know on a 2-stroke they improve breathing and power considerably but
>> >I'd always assumed that with the separate intake and exhaust cycles on a
>> >4-stroke there was no advantage to using a tuned pipe ?
>> >
>> >If I am wrong here does anyone know what sort of power increase that eg
>> >an OS 120 FS might expect from the addition of a full wave quiet pipe
>> >like the ones Just Engines supply ?

>>
>> I'm willing to bet that most 4 stroke pipes in use today are to route the
>> exhaust neatly through the belly pan, and to further silence the 4 stroke
>> sound.
>>
>> Bob

>
>
>
>
>
>
>
>
>



remove my-wife to reply :-)
Old Jul 27, 2003, 03:00 AM
Ed Cregger
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

My guess is that they are not worth the weight gain for aircraft use.

Ed Cregger


"Icrashrc" <icrashrc@aol.com.my-wife> wrote

> Don't tell the top fuel and funny car guys [and gals] that tuned exhaust
> doesn't work! Those may look like random pieces of pipe bolted on the head

but
> size and length are very critical.
>
> >I agree.
> >
> >Any power gain, if it truly exists, is purely coincidental.
> >
> >Ed Cregger
> >
> >
> >"Bob Adkins" <bobad@charter.net> wrote in message
> >news:k6b3iv0foge46f3mmgoimhe7tjsqlmiqrh@4ax.com.. .
> >> On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net>

wrote:
> >>
> >> >Hi I asked this before but noone answered, idk if the post showed or

not
> >?
> >> >
> >> >Anyway, I've seen tuned pipes advertised for use with 4-stroke

engines
> >> >and I wondered how much use they are ?
> >> >
> >> >I know on a 2-stroke they improve breathing and power considerably but
> >> >I'd always assumed that with the separate intake and exhaust cycles on

a
> >> >4-stroke there was no advantage to using a tuned pipe ?
> >> >
> >> >If I am wrong here does anyone know what sort of power increase that

eg
> >> >an OS 120 FS might expect from the addition of a full wave quiet pipe
> >> >like the ones Just Engines supply ?
> >>
> >> I'm willing to bet that most 4 stroke pipes in use today are to route

the
> >> exhaust neatly through the belly pan, and to further silence the 4

stroke
> >> sound.
> >>
> >> Bob

> >
> >
> >
> >
> >
> >
> >
> >
> >

>
>
> remove my-wife to reply :-)




Old Jul 27, 2003, 03:00 AM
Bob Adkins
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

On 26 Jul 2003 11:07:57 GMT, courseyauto@aol.com (Courseyauto) wrote:


> The only time a tune pipe would benifit on a 4 stroke is during the overlap
>time that both valves are open at the same time,which varies with camshafts. it
>is during this time that the exhaust would help pull intake charge into the
>cylinder.


Valve timing is too conservative on 4 stroke engines. I bet they would throw
prop nuts like popcorn if timed radically enough to use a pipe.

Bob
Old Jul 27, 2003, 03:00 AM
Paul McIntosh
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

That is exactly what the Macs pipe did on my OS .91 Surpass. In fact, it
made my engine TOO quiet! While racing, I couldn't hear my plane above the
others!

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"Bob Adkins" <bobad@charter.net> wrote in message
news:k6b3iv0foge46f3mmgoimhe7tjsqlmiqrh@4ax.com...
> On Tue, 22 Jul 2003 18:07:36 +0100, Boo <Boo@spam_me_no_spam.net> wrote:
>
> >Hi I asked this before but noone answered, idk if the post showed or not

?
> >
> >Anyway, I've seen tuned pipes advertised for use with 4-stroke engines
> >and I wondered how much use they are ?
> >
> >I know on a 2-stroke they improve breathing and power considerably but
> >I'd always assumed that with the separate intake and exhaust cycles on a
> >4-stroke there was no advantage to using a tuned pipe ?
> >
> >If I am wrong here does anyone know what sort of power increase that eg
> >an OS 120 FS might expect from the addition of a full wave quiet pipe
> >like the ones Just Engines supply ?

>
> I'm willing to bet that most 4 stroke pipes in use today are to route the
> exhaust neatly through the belly pan, and to further silence the 4 stroke
> sound.
>
> Bob



Old Jul 28, 2003, 03:00 AM
Boo
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120

Paul McIntosh wrote:
> That is exactly what the Macs pipe did on my OS .91 Surpass. In fact, it
> made my engine TOO quiet! While racing, I couldn't hear my plane above the
> others!


Hi Paul,

Does this mean you've actually tried a tuned pipe on a fs engine ? At
last ! Real people's experience ! Can you tell me what, if anything,
it did to the revs on a given prop ?

Thanks,

--
Boo

Old Jul 28, 2003, 03:01 AM
RCFlyr
Guest
n/a Posts
Re: Tuned pipe on a four stroke 120



Icrashrc wrote:
> Don't tell the top fuel and funny car guys [and gals] that tuned exhaust
> doesn't work! Those may look like random pieces of pipe bolted on the head but
> size and length are very critical.
>
>
>>I agree.
>>
>>Any power gain, if it truly exists, is purely coincidental.
>>
>>Ed Cregger
>>

Cannot speak for model engines, but I had a 1968 Honda CB-450K
motorcycle that I fitted with shorty megaphones. With these megaphones
all of the power went into making noise and the engine didn't run worth
a crap, especially at higher rpm's. The stock pipes performed much
better. We tried an experiment by lengthening the header pipes
incrementally and we reached a point where the bike actually would run
better than stock. But it was LOUD. In conclusion, we found that the
length of the exhaust does make a difference in 4-stroke engines.
However you will pay a penalty at either end of the rpm range depending
on the length of the pipes.

RCFlyr sed that!!

 


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