Talk:Tuned pipe

Tuned pipe
Absolutely not "tuned pipe" is street language not engineering language. The tuned pipe article itself is full of errors and half baked misconceptions. "Tuned pipe" should be deleted not merged.--=Motorhead (talk) 22:34, 13 April 2009 (UTC)

As far as I can see there is nothing covered in the tuned pipe article that is not also in the expansion chamber article Thatslife91 (talk) 19:01, 23 November 2010 (UTC)

I just read this article and it is factually inaccurate. The need for an expansion chamber is not purely because of the nature of the simultaneous cycles, it is instead because of the nature of symmetrical port timing. 115.64.159.41 (talk) 13:37, 26 December 2010 (UTC)

Undo "merge"
I've just undone a ham-fisted attempt to merge this article with expansion chamber. Although that is a reasonable aim a "merge" that is in fact simply a deletion of an article is not a true merge: in particular the "merged" article did not even the alternative term. Regardless of the ignorance displayed above, the term is widely used even in formal contexts. I suspect some the preference for expansion chamber is derived from ignorance or regional/national language differences. Crispmuncher (talk) 15:33, 22 March 2012 (UTC)


 * Claims of "ham fisted" and "ignorance" is a bit over-the-top. Regardless, I don't mind having a civilised discussion about it. I read both articles and found that the contents of 'Tuned pipe' was a subset of the contents of Expansion chamber. In many places they were word-for-word identical. It seems silly to have two articles covering the same topic. The normal way that we handle this on WP is to chose one article as the main article and have the other article become a simple redirect to the main article (like I did). The main article then has to have a little bit of cleanup, like making sure that the intro mentions the multiple names. 'Expansion chamber' already mentioned tuned pipes (the opposite of your claim above), although it could have been worded a bit better ('Expansion chamber' says the term "tuned pipes" is only for 4 stroke engines, but see comments below) . Multiple terms being redirected to a single article is normal, accepted WP practice. Note that this isn't considered deleting the old article because the information in 'tuned pipe' was already present in 'Expansion chamber'.


 * Personally, I have no great preference for either term. I chose 'Expansion chamber' to be the main article simply because it had more information in it (especially for manufacturing). Also, consider that tuned pipe(s) can mean:
 * two stroke exhaust system (aka expansion chamber),
 * tuned length exhaust manifold (typically used on 4 stroke car engines),
 * tuned length inlet manifolds (tunnel rams being just one example),
 * pipes in a pipe organ,
 * pan pipes
 * and probably a few more things I can't think of right now.
 * Perhaps 'Tuned pipes' should be a disambiguation page with links going to each of the above topics - including one going to 'Expansion chamber'.
 * Even if the terms 'tuned pipes' and 'expansion chamber' are regional terms, it is normal WP practice to chose one (arbitrarily by an outsider if the warring factions can't decide among themselves) and then make the other term a simple redirect. Making two duplicate articles covering the same information is just silly and definitely not encouraged on WP.  Stepho  talk 04:49, 23 March 2012 (UTC)

Requested move affecting this page
A request has been filed to rename Expansion chamber to Tuned pipe, see Talk:Expansion chamber. 70.49.124.225 (talk) 04:00, 30 April 2012 (UTC)

Merge to Expansion chamber
Same topic, simple duplication. Merge has already been done recently, but was reverted.

Merge tuned pipe (weakest & unref) into expansion chamber (the larger and slightly better).

Then (arguably) rename to Tuned pipe as a better name (see Talk:Expansion chamber). Tuned pipe describes the system and function, not just one component of it. Also expansion chamber has a couple of other unrelated uses within exhaust systems that don't belong within this clear scope. However I suspect that in the 1950s, "expansion chamber" was actually the more common term. Certainly Irving's Two Stroke Power Units (pretty much canonical for small two-stroke petrol engines of the period) uses expansion chamber but not tuned pipe.

Accordingly I strongly support merging, support TP->EC as the easiest direction, and weakly support a rename to TP, but wouldn't argue too much over that. Andy Dingley (talk) 13:36, 1 May 2012 (UTC)

I oppose the merge. Tuned pipes are used, for example, in conjunction with extractor manifolds. This is a distinct topic to expansion chamber. Andrewa (talk) 18:07, 9 May 2012 (UTC)


 * First of all, what does the eventual name have to do with the merge? There's nothing here in either article that isn't a simple overlap and directly related to two-strokes, and two-strokes alone. That's the reason for the merge.
 * If you want to discuss tuned pipes with extractor manifolds (and not for two strokes), then do so. If you want an article on tuned pipes other than two strokes, then we can do that with disambiguation on the names. Andy Dingley (talk) 20:14, 9 May 2012 (UTC)


 * I want articles that have names and leads that accurately describe their contents. These don't. The merge would help, but it's a short-sighted solution, in that you need to preserve the article histories somehow, and long term you'll end up with two article anyway. In that way, the proposed merge risks creating needless problems. See Talk:Expansion chamber.


 * In the context of petrol-fueled two-stroke engines which applies:


 * An expansion chamber is a type of tuned pipe.
 * A tuned pipe is a type of expansion chamber.
 * Tuned pipe and expansion chamber are two names for the same thing.
 * None of the above.


 * The first thing is to decide which of these four is true. Andrewa (talk) 00:58, 10 May 2012 (UTC)


 * I don't understand your point here. The two articles at issue are quite clear in stating what they intend to cover (whether they achieve this or not) and "Two stroke exhausts that use resonance to improve scavenging" is a clearly notable stand-alone topic. We should have an article on this. If we want another article on some other separate aspect too, then we can add that as another article.
 * In the context as described here, the two terms and the two articles refer to the same thing. Andy Dingley (talk) 01:21, 10 May 2012 (UTC)


 * OK. Then there's no question of two articles, one of them more specific than the other, covering this topic. The next question is, what's the best name for it? Above you say ...the name tuned pipe is much better than expansion chamber. It is also the rather more common everyday name for such a system. But as Stepho-wrs has pointed out here and elsewhere, there are other uses for the phrase tuned pipe. Is this the primary meaning of the term, and if not, how is it best to disambiguate it? Andrewa (talk) 02:28, 10 May 2012 (UTC)
 * I don't think we have to address the primary topic question at present, as this is also the only article under that name. For the time being, it (or its redirect) can go to tuned pipe. We disambiguate in the future, at the time we then need to because we have other topics too. If these already exist, then disambiguate this now as tuned pipe (two stroke engine), or whatever you think. Andy Dingley (talk) 07:31, 10 May 2012 (UTC)

Two things: 1) Both articles are reasonably technical, as is this discussion, yet neither article has any more than a very few references. That fact casts doubt on the content of both articles. Maybe they should be deleted because they lack notability. 2) The Tuned pipe article says its subject applies to two-stroke engines, while the Expansion chamber article says that the Tuned pipe applies to four-stroke engines. Which is it? Lou Sander (talk) 13:22, 10 May 2012 (UTC)


 * Cool. Let's agree that neither is notable, so please delete both (Then I might get a chance to just fix the damned things). Neither is a good article: they're unclear, they're unreferenced, much of them is just plain wrong.
 * The concept described here only applies (and can only apply) to two-stroke engines with long valve overlaps, generally meaning piston-ported engines (and four strokes aren't piston-ported). If this needs disambiguation (which it doesn't yet have), from articles on other tuned pipes (that don't exist yet), then no-one cares if the name gets changed - however WP practice is to not do that until it's actually needed. This is a good scope for an article on a notable topic - this much is unarguable and trivially easy to reference.
 * There is possibly some confusion with organ pipes (we can just call those organ pipes) and also with four-stroke exhaust systems. There is no overlap with four-stroke exhaust systems, even if the term has been borrowed by four-stroke mechanics afterwards. Those are different devices, they don't belong in this article. Andy Dingley (talk) 14:15, 10 May 2012 (UTC)

http://www.shop4exhaust.com/t-Long-and-Short-Tube-Headers.aspx ''Because a tuned pipe cannot be effective over the full spectrum of the RPM, it has to be "tuned" for a certain RPM range. Usually, high performance headers are tuned for the lower RPM because that's where most engines have weakest horse power and torque. By adjusting the exhaust pipe's total length the engine can be "tuned” at the pipe. During a testing or development phase most tuned headers are cut at the coupler that connects exhaust manifold and tuned pipe little by little and test driven until improvements are seen at desirable RPM band. Generally longer pipe moves the effective band of tuned pipe to lower RPM range, and shorter length moves the effectiveness band to higher RPM.'' (my emphasis)

This is talking about four-stroke systems. Now, the current tuned pipe article is just about two stroke systems, but is there any reason that the article should not be expanded to include these four-stroke systems? They do have some things in common with the two-stroke version, while there are also important differences. Andrewa (talk) 04:35, 12 May 2012 (UTC)

On reflection, I've decided to try the opposite approach, and create a new article covering both two- and four-stroke systems at tuned exhaust.

Please see Talk:tuned exhaust.

In view of this I now agree that this article and the one at expansion chamber should be merged, but I don't see either title as particularly good in terms of WP:AT. Is there another possible title for an article on two-stroke systems specifically? Andrewa (talk) 19:51, 15 May 2012 (UTC)

See also Talk:Expansion chamber and particularly Talk:Expansion chamber where I suggest that the merge proposal hasn't failed at all. Andrewa (talk) 10:25, 1 June 2012 (UTC)

Lead
I've had a go at clarifying the article scope as described in the lead. 

I haven't yet touched the sentence Its purpose is to retain the air/fuel mixture in the combustion chamber by using the pressure wave produced by the combustion process itself and bouncing it back to the exhaust port at the appropriate time, thus precluding the fresh charge, which comes through the transfer ports, to follow the exhaust gases. But I'm skeptical that this is accurate.

Is the pressure wave really produced by the combustion process itself, or is it produced by the opening of the exhaust port?

I'm a bit skeptical of that word preclude as well. That would mean it completely prevented it, but that's only true in a fairly narrow rev range. Andrewa (talk) 21:45, 11 May 2012 (UTC)

I note also that this is significantly different to the current lead at expansion chamber: ''An expansion chamber is an exhaust system used on a two-stroke cycle engine to enhance its power output by improving its volumetric efficiency. It makes use of the energy left in the burnt exhaust exiting the cylinder to aid the filling of the cylinder for the next cycle. It is the two-stroke equivalent of the tuned pipes (or headers) used on four-stroke cycle engines'' (my emphasis).

IMO both leads still need work. Clarify the scopes of both articles, and the merge/move issues will become a lot clearer. See also Talk:Expansion chamber. Andrewa (talk) 00:14, 15 May 2012 (UTC)

Proposed redirect
The useful content of this article (currently at tuned pipe) seems to now be entirely duplicated in the expansion chamber article. There's been a lot of discussion and activity regarding moves and merges (and I've been part of the discussion, but haven't moved any material myself), but it all seems academic now. The situation we need to address is that this article probably has a useful history which we should preserve, but has no useful content.

This page should become a redirect, immediately. But where to? The obvious candidates are:


 * Expansion chamber, an article on tuned two-stroke exhaust systems. The main problem with this is that, according to that very same article, the term tuned pipe applies to four-stroke systems. It could also be argued that the expansion chamber is just part of the tuned exhaust system, as it doesn't include the manifold, the length of which is a vital part of the tuning.
 * Tuned exhaust, an overview article on both two-stroke and four-stroke systems.
 * Tuned pipe (disambiguation).

Anyway, my proposal is that this page should redirect to one of those (I don't really mind which) as a first step, and we can then get on with cleaning up and possibly moving the article at expansion chamber (which BTW has some issues, but as I've said before also has a lot of good material. Overall I like it a lot.) Andrewa (talk) 08:01, 4 June 2012 (UTC)

See also Talk:Expansion chamber, where I posted a heads-up on this proposal which has now seen some discussion there. The discussion there so far seems to support this proposal but it's not all that clear to me so I'm very interested in other views on this.

It still seems to me that that discussion concerning making this article a redirect is best on this talk page. Andrewa (talk) 09:53, 4 June 2012 (UTC)


 * OK, to re-state my comment at the other page, because you claim that it's not valid if I make it at that page, even though it seems you're about to hide this talk page behind a redirect anyway (great way to stop future readers noticing the audit trail).


 * Just to clarify, the above bullet is part of the post by Andy Dingley at 10:09, 4 June 2012 (UTC), in reply to these edits of mine at Talk:Expansion chamber. But I have no intention of redirecting the talk page, I see no reason to do that and every reason not to. Nor do I claim that it's not valid if you make it at that page, but I do think the discussion is more helpful here. Andrewa (talk) 06:59, 5 June 2012 (UTC)


 * Do not redirect tuned pipe or expansion chamber to tuned exhaust They are different topics, or at least notable sub-topics, within the broader scope. Andy Dingley (talk) 10:09, 4 June 2012 (UTC)


 * Agree that redirecting (or even merging) expansion chamber to tuned exhaust is not a good idea. The article at tuned exhaust is quite long and detailed enough. A separate main article on tuned exhausts in two-stroke engines is best (as I've always said).


 * Have you any objection to redirecting tuned pipe (in the article namespace only, not this talk page) to expansion chamber, as suggested above?


 * As also stated above, there is an unreferenced claim at expansion chamber that it is the two-stroke equivalent of the tuned pipes (or headers) used on four-stroke cycle engines (my emphasis). Do you have any opinion or even reference as to whether or not this is true? Because if it is true, then surely the redirect from tuned pipe should be to the more general article at tuned exhaust, which covers both the two-stroke and four-stroke versions? But if it's not true, then the redirect should go to the article currently at expansion chamber.


 * But I'm certainly not going to redirect to tuned exhaust without consensus here. I do want to document here the reasons for the decision, whatever it is, just in case others wish to review it later. Andrewa (talk) 06:59, 5 June 2012 (UTC)


 * is the two-stroke equivalent of the tuned pipes (or headers) used on four-stroke cycle engines
 * Of course this isn't true. How many times have I said that it wasn't true, that the two existing articles were poor, that they needed rework to fix them, and that existing WP articles aren't WP:RS for fixing WP articles. Just because a poor article makes a particular statement, why on earth would that become some dogmatic axiom that we have to base the rest of our content about? It's just wrong, based on a misunderstanding of how the different systems work. You seem to be hanging onto this point at all costs, once again to justify redirecting a potentially good topic for two-strokes alone to your new article at tuned exhaust. Andy Dingley (talk) 10:36, 5 June 2012 (UTC)


 * Please read No personal attacks. It's not optional. As I've said before you have an awesome edit history. Please familiarise yourself with the fundamental policies, including that one and Civility.


 * I have asked before whether you disagree with this claim, and I'm afraid that if you've answered the question I've missed it. And you have said that the existing articles are poor, and I've agreed. But I think we also agree that there is lots of material at expansion chamber worth saving. We need to be specific about what is good there and what is not.


 * So, let's get on with it. As I said above, sources to support the claim that tuned pipe is not a term used for four-stroke tuned exhausts would be good. Those belong here in this talk page, as evidence justifying the redirect which I among others have proposed to expansion chamber.


 * And you haven't explicitly said here that you support this redirect to expansion chamber, but you have said elsewhere Yet again, you oppose a correct merge proposal. This immediate redirect would be tantamount to deleting the article instead, which is not the goal required. As the article doesn't have much content to offer to a merge to expansion chamber, then this does seem like a route to the same end result though.


 * Can you understand why I'm a bit reluctant to take this as support for the redirect proposal? But unless you explicitly say here that you oppose the redirect to expansion chamber, that's what I think I should do for now.


 * And if you provide sources to back up your claim about the four-stroke version, I think it should stay that way. Otherwise, you're quite right to fear that it may not. Andrewa (talk) 20:10, 5 June 2012 (UTC)


 * You do so love the sound of your own voice, that much is clear. Once again, I don't care about any of these articles. You WP:OWN them, you are clearly going to do whatever you like to them, despite whatever any real sources support (and I gave you real ones from Irving and Smith ages ago) and certainly whatever I say. You ask me to cite refs to prove a negative, but at the same time you build whole extra articles (and or two duplicate articles are now five, with added organ pipes) based on "references" from crappy Jimmy & Bubba car-tuning websites. You might have time for this nonsense, others don't. Andy Dingley (talk) 21:33, 5 June 2012 (UTC)


 * Well, if you do have sources, please cite them, either here or in the appropriate article. Or at least a diff to say where you cited them before. I'm sorry if you feel that this is repeating yourself.


 * You say Irving and Smith... is one of the references you have provided Irving's Two Stroke Power Units (pretty much canonical for small two-stroke petrol engines of the period) uses expansion chamber but not tuned pipe . Phil Irving is certainly a citeable authority on both two- and four-stroke engines, but as this work is about two-stroke engines it's not likely to tell us whether the term tuned pipe is also applied to four-strokes, which is the question here, and you say he doesn't use the term for two-strokes anyway, so that particular post and source seems irrelevant.


 * I'll see if I can find your Smith reference. Andrewa (talk) 06:53, 6 June 2012 (UTC)


 * Phil Irving
 * The Expansion-chamber system,
 * P.H. Smith
 * All of these describe the two stroke system using resonance to improve scavenging, just as previously described. Both authors use the term "Expansion Chamber" to name this, rather than tuned pipe.
 * It was pointed out to me over the weekend by an ocarina maker that one reason for this might be that they're not strictly tuned pipes, any more than an ocarina is - they're more like Helmholtz resonators, which operate by the elasticity of a volume of gas, rather than by linear wave propagation.
 * Some of these refs also describe four stroke exhausts, although they're clear that the effect described for two strokes plays no part in how an efficient four stroke exhaust is designed: the desired effects, and the means to achieve them, are still different. It is however rare to find any text that describes exhaust systems for both two strokes (of the crankcase compression type) and four strokes: there's just little crossover between motorbikes and the rest. I have a few books on the construction of hillclimb cars ('60s-'70s) that do this, but I wouldn't regard them as particularly authoritative on exhausts. Similarly for my engine tuning and head gasflow books. Smith's (Scientific Design of...) is just about the only one that does cover both. Andy Dingley (talk) 13:09, 6 June 2012 (UTC)
 * All of these describe the two stroke system using resonance to improve scavenging, just as previously described. Both authors use the term "Expansion Chamber" to name this, rather than tuned pipe.
 * It was pointed out to me over the weekend by an ocarina maker that one reason for this might be that they're not strictly tuned pipes, any more than an ocarina is - they're more like Helmholtz resonators, which operate by the elasticity of a volume of gas, rather than by linear wave propagation.
 * Some of these refs also describe four stroke exhausts, although they're clear that the effect described for two strokes plays no part in how an efficient four stroke exhaust is designed: the desired effects, and the means to achieve them, are still different. It is however rare to find any text that describes exhaust systems for both two strokes (of the crankcase compression type) and four strokes: there's just little crossover between motorbikes and the rest. I have a few books on the construction of hillclimb cars ('60s-'70s) that do this, but I wouldn't regard them as particularly authoritative on exhausts. Similarly for my engine tuning and head gasflow books. Smith's (Scientific Design of...) is just about the only one that does cover both. Andy Dingley (talk) 13:09, 6 June 2012 (UTC)
 * All of these describe the two stroke system using resonance to improve scavenging, just as previously described. Both authors use the term "Expansion Chamber" to name this, rather than tuned pipe.
 * It was pointed out to me over the weekend by an ocarina maker that one reason for this might be that they're not strictly tuned pipes, any more than an ocarina is - they're more like Helmholtz resonators, which operate by the elasticity of a volume of gas, rather than by linear wave propagation.
 * Some of these refs also describe four stroke exhausts, although they're clear that the effect described for two strokes plays no part in how an efficient four stroke exhaust is designed: the desired effects, and the means to achieve them, are still different. It is however rare to find any text that describes exhaust systems for both two strokes (of the crankcase compression type) and four strokes: there's just little crossover between motorbikes and the rest. I have a few books on the construction of hillclimb cars ('60s-'70s) that do this, but I wouldn't regard them as particularly authoritative on exhausts. Similarly for my engine tuning and head gasflow books. Smith's (Scientific Design of...) is just about the only one that does cover both. Andy Dingley (talk) 13:09, 6 June 2012 (UTC)

OK, I think we're getting somewhere. Lots of good observations here.

Agreed that there is little crossover between two and four stroke systems. But disagree that this is a contrast between motorbikes and the rest. Four-stroke motorbikes are often fitted with aftermarket extractors in Australia. Tuned expansion chambers are fitted to two-stroke engines in many applications, including model engines, aircraft engines, motorbikes and even some cars (and as noted before Wikipedia does not seem to cover the cars at all at present, if we do I can't find it).

There is some crossover. Both are accurately described as tuned exhaust systems. Both are a compromise that works best at a particular engine speed. And in both cases it seems that there have been motorcycles that have used variable exhaust geometry to broaden the engine speed range at which the tuned exhaust is effective (I didn't know this until researching these articles, I think it's even a possible WP:DYK if it can be better sourced).

Agree that the two-stroke systems are, technically, a Helmholtz resonator rather than a tuned pipe.

But at the risk of harping, the question here is simply, are readers likely to visit the URL http://en.wikipedia.org/wiki/Tuned_pipe (or any of its aliases) seeking information on four-stroke systems? If not, then the redirect should clearly go to the article on two-stroke systems (or to the DAB, depending on other considerations). But if they are, then there's a case for it going somewhere else.


 * (And nor is it relevant whether for four strokes it's more trouble than it's worth . This may be true for motorcycles for all I know, but as I understand it and have said before, more generally and in many cases both on the road and in competition, they are well worth the effort. There are many dyno tests showing this, and much money has been spent on them by makers who don't need to impress anyone with gimmicks. But in many other cases they are not. In particular, many aftermarket exhausts for both cars and motorcycles give no scavenging benefit at all, because the relatively expensive development work necessary to achieve results has simply never been attempted. Far cheaper just to weld up and chrome something that looks and sounds fast, and sadly, likely to sell better too! I expect you've read magazine articles which said something like that, there have been many. A few aftermarket inlet manifolds are even worse, built to enable an expensive aftermarket carbie to look impressive and not require extensive body mods, and with little or no attention to gas flow.


 * But that's content, not navigation, and irrelevant here. What's relevant is, is the four-stroke case an encyclopedic topic, and how do we best cover it if so. Extractor manifolds are common enough that I think we should cover them, and that would remain true even if it were shown that none of them actually achieved any performance benefit. Andrewa (talk) 20:34, 7 June 2012 (UTC))

And even then, if the overwhelming majority want the two-stroke case, a hatnote there is a better solution for those who want the four-stroke system. That's why I'm not all that worried which of the three possible redirects we end up with. It's very difficult to tell which is best, and frankly I'm not convinced that Wikipedia makes such decisions well or consistently, or even that it matters all that much.

Similarly, the fact that the name tuned pipe is technically inaccurate for the two-stroke system is interesting but irrelevant to this particular discussion. All that's at issue here is that people do commonly use that name, and so we want to provide navigation aids to get them to the information they want. When they get there the article may well include the information that the name they are using is a misnomer, but that's a matter of content, not navigation. Andrewa (talk) 14:43, 6 June 2012 (UTC)

Done
Discussion seems to have petered out, consensus is still not all that clear but there's a strong consensus to do something rather than nothing, so I've been bold  probably not before time. Andrewa (talk) 22:40, 10 June 2012 (UTC)