So...Chuff Pipes

dougrail · Post by **dougrail** » Mon Jul 23, 2012 11:37 pm

Chuff pipes. They appear to be like marmite - people either love them or hate them. Some say they decrease engine performance as they choke the exhaust, others say they improve the whole garden railway experience by the sound.

Small engines, big engines, all sorts have them fitted. The question is, do they decrease performance, especially on smaller engines? re they worth fitting on say, an IP Jane or does it take off performance?

All input appreciated

DLRdan · Post by **DLRdan** » Tue Jul 24, 2012 9:14 am

It depends on the volume of steam you are sending through them. A small volume can pass through fairly quickly where as a large volume goes through slower creating back pressure. It won't affect a Mamod/Jane but it would a Roundhouse or Accucraft as it acts like an exhuast regulator. I doubt under normal circumstances it would have any noticable difference, it would be when you get NWAG length trains going up hills you would tell.

Adam R · Post by **Adam R** » Tue Jul 24, 2012 9:17 am

Personally, I think they sound awful. They sound just like a model steam engine with condensate trapped in the cylinders, so much so, my baldwin, runs without the factory one, and just stops at the valve block.

Its silent on its own, UNTIL it hits a bank or you lob a train behind it, It chuffs something lovely from the smokebox and gas burner being forced induction, it wont extuinguish it.

I may be tempted to put a short length of 4~5mm brass pipe halfway up the smokebox, but I see no point, the condensate clears fast the way it is, the engine is poweful until it starts to slip.

Each to their own, But I can think of a better way's to spend £25 odd.

dougrail · Post by **dougrail** » Tue Jul 24, 2012 9:28 am

Let's ignore the price factor as mine I scavenged for gratis [free- that's right!]. So on a Mamod/Jane/oscillator it doesn't affect the performance apparently? Cool.

Narrow Minded · Post by **Narrow Minded** » Tue Jul 24, 2012 9:33 am

Adam R:73118 wrote:Personally, I think they sound awful.

As you say, "each to their own" - I personally think they're great, especially when the loco's are being driven at scale speeds (In fact, they sound awful when the loco's are racing around the track - Pet Hate!)

I can think of a better way's to spend £25 odd.

Several people have demonstrated that you don't have to spend £25 on a bespoke chuffer, though IMHO the money spent buys you a quality product

Getting back On Topic, I was once told that "pinching" the end of a modified Mamod exhaust to act as an exhaust regulator and creating that bit of back pressure actually helps tame the run-away tendancies of the oscillators. I've done it to mine and it seems to have worked. It even produces a slight "chuff"

Adam R · Post by **Adam R** » Tue Jul 24, 2012 11:26 am

Ah I appear to have lost the bit in my post about how the Original 'chuff' pipe restricted performance, ill rewrite in more depth

If the exhaust is restricted it means the incoming steam has to 'work harder' to force the exhaust steam out.

If i remove the exhaust off the landrover, it goes like stink, but the fuel economy goes down, because the FLOW of the engine is increased. Stick in top and it will pull away at idle

The exhaust restricts it to a sensible power and increases the fuel economy. Stick it in top, it will stall at idle

you'll find with no chuffer, it will use marginally more steam, but have marginally higher power, with a chuffer it will use less steam, but have less power.

In this scale, were usually stopped by lack of adhesion rather than lack of power available. (what we really need is scale sanding gear[ill get my coat])

I strand to be corrected, but the chuffers are a pipe with a notch cut in them, the chuff is created by the steam being forced past making a noise. If the steam could just drift past, with no resitstance there would be no noise.

the baldwin with no chuff is virtually silent off the mark light engine, but as soon as it takes up some drag on the drawbar, it will chuff through the relatively narrow opening on the block under the smokebox. This will also be 'dry' as in no blobs of condensate bubbling round.

A blastpipe in a real loco is there to increase the velocity of the steam and create a vacum in the tubes/ lower smokebox, drawing air through the fire.

Doug, you have one for free, test it on both locos's and see what it does, surley it only takes seconds to remove.

I just dont think they are very chuffy, When i hear one, I dont appriciate the 'chuff' I just get a bit fed up with the asmatic straw in pop syndrome the ones ive heard suffer from.

My previous post is not intended to undermine any company producing these, its an honest opinion. If I wanted one, id probably make one, but ive never felt the need.

If anyone has an idea on how to shut an accucraft burner up, id be your best friend, mesh doesnt tend to last forever.

dougrail · Post by **dougrail** » Tue Jul 24, 2012 1:42 pm

Adam R:73126 wrote:Ah I appear to have lost the bit in my post about how the Original 'chuff' pipe restricted performance, ill rewrite in more depth

Seems so. Right, time for me to pay attention...

If the exhaust is restricted it means the incoming steam has to 'work harder' to force the exhaust steam out.

If i remove the exhaust off the landrover, it goes like stink, but the fuel economy goes down, because the FLOW of the engine is increased. Stick in top and it will pull away at idle

Aha. So in short it's a trade off between restraining power for better fuel, or more power but with less runtime on the gas ultimately.

The exhaust restricts it to a sensible power and increases the fuel economy. Stick it in top, it will stall at idle

With oscillators [Mamods anyway] usually a good thing given the runaway speeds they have?

you'll find with no chuffer, it will use marginally more steam, but have marginally higher power, with a chuffer it will use less steam, but have less power.

I see what you mean here. What if the engine in question is a hell of a steamraiser though - 60psi, and the SV is fountaining out steam even as the motion is going. Might as well take out the chuff and let that extra steam power the loco more, would I be right?

In this scale, were usually stopped by lack of adhesion rather than lack of power available. (what we really need is scale sanding gear[ill get my coat])

Lack of adhesion is always a problem - I'd love RC sanding gear but I also know it would terminally kill oscillators!

I strand to be corrected, but the chuffers are a pipe with a notch cut in them, the chuff is created by the steam being forced past making a noise. If the steam could just drift past, with no resitstance there would be no noise.

Looking at the Summerlands Chuffpipe which is what I scavanged for grat, pretty much yes but the 'end' of the pipe is also sealed - the steam has to come out of the side hole.

the baldwin with no chuff is virtually silent off the mark light engine, but as soon as it takes up some drag on the drawbar, it will chuff through the relatively narrow opening on the block under the smokebox. This will also be 'dry' as in no blobs of condensate bubbling round.

Dry steam being better than wet steam, so to speak...and the chuffpipe being metal creates minute blobs of condensate?

A blastpipe in a real loco is there to increase the velocity of the steam and create a vacum in the tubes/ lower smokebox, drawing air through the fire.

Doug, you have one for free, test it on both locos's and see what it does, surley it only takes seconds to remove.

On my Caradoc, which also has one fitted [!] it goes very nicely with the engine. My main study is with the oscillator Janet type - super gas burner, 60psi gas boiler, namely spoilt rotten

I'll remove mine and see what happens.

I just dont think they are very chuffy, When i hear one, I dont appriciate the 'chuff' I just get a bit fed up with the asmatic straw in pop syndrome the ones ive heard suffer from.

My previous post is not intended to undermine any company producing these, its an honest opinion. If I wanted one, id probably make one, but ive never felt the need.

If anyone has an idea on how to shut an accucraft burner up, id be your best friend, mesh doesnt tend to last forever.

Accucraft burner help always appreciated in these parts too! Now, back to the sound - it's a bit of both with me. When I've got the engine working hard with a good train it sounds very very convincing. However on light loads and light engine movements, it clickclickclickclicks. That's right, it clicks, kind of like a percolator or a cricket. It's become a trademark of the engine but can be a little bit offkilter with the whole 'steam engine' realism.

Thanks for the detailed help Adam, very much appreciated. Now to decide whether to remove before Sunday or not...

Adam R · Post by **Adam R** » Tue Jul 24, 2012 1:52 pm

Build up a good train

Keith S · Post by **Keith S** » Tue Jul 24, 2012 2:26 pm

Sorry, but the only sensible issue here is whether you like the sound or not. If the device altered the engine's "performance", which I am inclined to doubt, honestly, how many fewer wagons would it pull? With or without the chuff pipe these engines can already pull more wagons than a similar full size engine.

I personally think it's a trade-off; there are some situations like when you're running at greater than a proper scale speed, when the extra noise makes the engine just sound kind of funny; a real one would sound funny at those RPMs too. At scale-ish speeds when the engine is drawing a load, I think it sounds pretty good: certainly more appealing than the fizzing and popping most otherwise completely silent gas-fired engines make. When the engines are loaded up close to limit of their ability to pull without slipping, they will make a decent chuffing sound without the chuff pipe, but maybe they are more or less fun to play with when they are that heavily loaded, I don't know, I don't have enough wagons...

Anyway, you should decide if you like the sound or not. "Performance" sounds like a silly consideration, unless you're racing them...

dougrail · Post by **dougrail** » Tue Jul 24, 2012 2:55 pm

Keith S:73135 wrote:Sorry, but the only sensible issue here is whether you like the sound or not. If the device altered the engine's "performance", which I am inclined to doubt, honestly, how many fewer wagons would it pull? With or without the chuff pipe these engines can already pull more wagons than a similar full size engine.

Is it though? This is what I wished to find out. I do likethe sound and even the 'clicking' I've grown used to as 'part of the engine'. Soif it was just acoustics, I'm keeping it. However performance considerations have to be taken into account as I care to maximise the potential of the design.

I personally think it's a trade-off; there are some situations like when you're running at greater than a proper scale speed, when the extra noise makes the engine just sound kind of funny; a real one would sound funny at those RPMs too. At scale-ish speeds when the engine is drawing a load, I think it sounds pretty good: certainly more appealing than the fizzing and popping most otherwise completely silent gas-fired engines make. When the engines are loaded up close to limit of their ability to pull without slipping, they will make a decent chuffing sound without the chuff pipe, but maybe they are more or less fun to play with when they are that heavily loaded, I don't know, I don't have enough wagons...

Anyway, you should decide if you like the sound or not. "Performance" sounds like a silly consideration, unless you're racing them...

Not quite racing but I am looking to as said, maximise the performance of my little engine and if the chuffpipe hinders that, then it must go.

Thanks for the sage advice Keith!

Pendo Pilot · Post by **Pendo Pilot** » Tue Jul 24, 2012 3:50 pm

I run chuff pipes in almost all my locos (summerlands type). I like the sound they make when driven properly. No more restricted than a normal RH or accy pipe IMHO. In the example of my lady Anne (a modern version) the thing was totally silent when running, now produces a good chuff & much easier to drive from sound. All my fitted loco's have not lost one bit of power or running times. The Carrie for instance barks away superb with load 20 up my grades, probably better than it did as standard. All the mucky water thrown out is now directed below the loco even on "wet" steamers in the accy range.
I'm really happy that I tried them out tbh & the ease of fitting to most locos helped. Just the Fowler to do, but that is going to be a pain due to the riveted on old style smokebox.

Gremlin · Post by **Gremlin** » Tue Jul 24, 2012 4:19 pm

I've made a couple and tried to get a slightly deeper sound than some I've heard. I don't like them when they are too high pitched or hissy. Here is the one I made for my Lady Anne, which I'm quite happy with.
http://www.youtube.com/watch?v=we5d4GukQ-s

Dr. Bond of the DVLR · Post by **Dr. Bond of the DVLR** » Tue Jul 24, 2012 4:36 pm

I have fitted chuff pipes to all my locos and think they are grand. I try to drive all locos at a speed suitable for my line, with its sharp curves and short end to end nature that speed is very slow so I think they sound good with each beat distinct and clear.

The best chuff pipe I've ever heard is on the cheddar Samson in this video:
http://www.youtube.com/watch?v=X2lffq4m8Zw
and here:
http://www.youtube.com/watch?v=9QwK_yU5 ... el&list=UL

GTB · Post by **GTB** » Tue Jul 24, 2012 5:23 pm

Adam R:73126 wrote: If anyone has an idea on how to shut an accucraft burner up, id be your best friend, mesh doesnt tend to last forever.

Milton Loco Works make changeover burners for Accucraft locos that are similar to a Roundhouse burner, with rows of holes rather than slots.

http://www.appc27.dsl.pipex.com/frameset-1.htm Click on 'Accucraft Parts 2' and scroll down.

No idea how well the MLW ones work, but when the first slotted burner I made wailed like a Banshee, I built a new one with circular holes similar an RH burner. It now burns quietly and I had to fit a smaller jet so the safety valve wasn't continuously lifting.

Graeme

Keith S · Post by **Keith S** » Tue Jul 24, 2012 7:27 pm

Well Doug, from a performance standpoint, I work with gas turbine engines at my job, and I can tell you that every time a flowing fluid has to take a ninety degree bend, it loses energy. Also anything that causes drag in the fluid flow causes it to lose energy. So the stock exhaust pipe must also go, since it is pinched off at the top with a little hole drilled in it. This causes turbulence in the exhaust stream, and is an artificial restriction. The hole is probably the same size as the exhaust ports in the cylinders or the reversing valve, and so probably doesn't cause back pressure to any greater extent than the friction imparted to the exhaust stream from the walls of the pipe itself. You'd do best to completely remove the exhaust pipe and allow the exhaust to blast right up the chimney from the hole on top of the cylinder block. You'd do even better to eliminate the reverser altogether and let the cylinders exhaust straight to atmosphere, but then the engine would only go forwards.

If anything the passages and opening inside a Summerlands chuffer are greater in area than the exhaust pipe itself, so I can't see it causing any back pressure. It does generate turbulence in the exhaust stream, and this turbulence is optimized by the design of the chuffer to be audible in the form of a hissing sound which bounces around in the chimney and smokebox to sound like a locomotive chuff. Making sound waves robs the exhaust stream of some of its energy, strictly speaking causing it to slow in velocity and rise a tiny bit in pressure, but I would doubt it is any more energy than is lost to friction from the stock exhaust pipe anyway. This phenomenon is measurable in the intake in a turbine engine moving at close to the speed of sound, but in a little steam engine? Never. Therefore I don't think the chuffers cause any measurable back pressure. You must remove the exhaust system altogether to make your engine pull any more wagons. I really think you need to focus more on whether you like the sound. I'm absolutely sure the engine doesn't "feel" the chuffer!

Anyway, if you were after a performance machine, you should mount a marine flash-steam boiler on a chassis with rubber wheels and a valveless single-acting pair of cylinders driving some reduction gears.

When I demonstrated my roundhouse engine to the engineers at work, I had it dragging a flat wagon with a five-gallon bucket of de-icing fluid on top, and the thing the guys liked the most about the whole show was how much they thought the engine sounded like "a real one". This is why you get a chuffer. If performance is your goal, get rid of the exhaust and the reversing block, remove the cab, tanks, chimney and smokebox, and anything else that causes drag or unnecessary weight, put rubber tyres on the wheels, and boost the boiler pressure. That should fix it!

benchmark · Post by **benchmark** » Tue Jul 24, 2012 8:24 pm

I think they sound great and more realistic. I have not noticed any loss in performance of the loco but even it if does, i do not mind sacrificing a little performance for that sweet sound.

laurence703 · Post by **laurence703** » Wed Jul 25, 2012 5:48 pm

Spotted this on Youtube... There is certainly a difference on an Accucraft Caradoc... it has a clip of before and after.

http://www.youtube.com/watch?v=UbVq9cHV ... re=related

Chris Bird · Post by **Chris Bird** » Thu Jul 26, 2012 3:16 pm

Hi folks
Well I just found this thread - and it is interesting to see the conjecture about back pressure. I was pleased to see that Keith S has got it right - there is no increase in back pressure from a Summerlands Chuffer. The jet is precision drilled, is the same diameter as the exhaust and is fractionally larger than some. The slot is much larger. The sound is not from any restriction it is from turning the exhaust through 90 degrees across the end of a resonator.

To give you an example, the massive Accucraft K-27 uses a 3mm exhaust and the boss that screws in has a hole smaller than the Chuffer. The loco will pull a house.

Other types of chuff pipe often do use a constriction to make the sound, by crimping the end of the pipe.

The sound is determined by the loco and the accoustics of the chimney and smokebox. A Mamod sounds different from a Caradoc, which is different from a Katy. There is a video of a Hercules just posted - and it is different again.

Also please remember that I personally guarantee your money back if you don't like it, don't fit it or any other reason within 8 weeks.

In the end - it is just a matter of what you like - I happen to like my locos to chuff!

Cheers
Chris
Summerlands Chuffer

dougrail · Post by **dougrail** » Thu Jul 26, 2012 5:53 pm

Hi Chris,

Please [and all forumfolk] note that this wasn't a stage on which to criticise or otherwise demolish the Chuffpipe. I was merely curious about whether they did diminish loco performance whatsoever. However having one on both my Caradoc and my PPS Jenny, provided performance is not affected I am more than happy wth mine.

Chris Bird · Post by **Chris Bird** » Thu Jul 26, 2012 10:46 pm

dougrail:73237 wrote:Hi Chris,

Please [and all forumfolk] note that this wasn't a stage on which to criticise or otherwise demolish the Chuffpipe. I was merely curious about whether they did diminish loco performance whatsoever. However having one on both my Caradoc and my PPS Jenny, provided performance is not affected I am more than happy wth mine.

Well Dougrail, I am always delighted to see discussion on the subject and it is only right that opinions vary - but I do like to get the facts straight when I went to so much trouble to be sure my Chuffer didn't affect performance. Oh yes - and 'demolished' chuffers are no problem as we fix them for free when customers overtighten them or mistakenly try modifications

Cheers
Chris

Cheers

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So...Chuff Pipes

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