Talk:Tuned exhaust

New stub

There are already existing articles on two-stroke engines at tuned pipe and expansion chamber, and some controversy over their future, with a proposed move and a proposed merge and much discussion.

Wherever those two articles end up, there's enough material I think for an overview article covering both two- and four-stroke engines. This is it.

Note that it's not a content fork of either of these. Both of these other articles are currently [23] [24] scoped explicitly to two-stroke engines.

Note also that, having created this stub, I've now dropped both my opposition to the merge of tuned pipe and expansion chamber [25], and my alternative proposal to instead broaden the scope of tuned pipe [26] [27].

I still think that we ultimately need two articles, but this is now one of them, so the other two can now merge. Andrewa (talk) 12:35, 16 May 2012 (UTC)

And those two are now merged, albeit rather messily. Andrewa (talk) 18:55, 13 June 2012 (UTC)

Please be careful

Note that the articles at tuned pipe and expansion chamber currently [28] [29] are not consistent with each other, and are poorly referenced. It's bad enough that one contributor seriously suggested deletion, admittedly a while ago [30], claiming "tuned pipe" is street language not engineering language. The tuned pipe article itself is full of errors and half baked misconceptions. That's my impression too, frankly.

So please be very careful copying or merging material from either of these articles to here. Andrewa (talk) 19:37, 15 May 2012 (UTC)

Just to emphasis this, a third contributor described the tuned pipe and expansion chamber articles as one poor, one really bad [31]. This particular post is even more severe in its criticism of this article, admittedly!

As a glaring example, the lead to the expansion chamber article currently [32] reads in part It is the two-stroke equivalent of the tuned pipes (or headers) used on four-stroke cycle engines (wikilink as in the article, my emphasis). But the tuned pipe article is currently [33] also specifically and only about two-stroke engines, and this point has been forcefully made by other contributors, most recently and perhaps most forcefully in the same post that said one poor, one really bad. Umm, yes! Andrewa (talk) 00:11, 3 June 2012 (UTC)

Apart from your passive-appressive sniping at other editors, why have you been so vociferous in opposing any attempt to clean up those two articles? Andy Dingley (talk) 00:38, 3 June 2012 (UTC)

I support cleaning up the articles and always have, and have also supported merging them since this edit a fortnight ago. Andrewa (talk) 05:05, 3 June 2012 (UTC)

And they are now merged, see above. Andrewa (talk) 03:27, 14 June 2012 (UTC)

Terminology

The heated discussions regarding tuned exhausts seem to be largely about terminology, so this section is a little think tank as to what the various terms might mean. Contributions welcome, preferably with some sort of reference. Sources here don't need to be up to article standards of reliability, although the more reliable the better obviously. Any source is better than none here, which is not true in the article namespace.

There are many issues, among them and local national varieties of English, use of jargon, and the varying reliability of sources, including websites and also published magazines.

I suggest that we keep the subsections alphabetical, one per term. And it's a talk page, so please sign your contributions.

Feel free to disagree with any of my attempts at definitions, and to add new subsections for other relevant terms. Mine are mainly from Google and/or off the top of my head so far. I'll try to add citations in time, even if only to examples of usage on the web, and even find some reliable sources maybe. And help is more than welcome with this too.

Again, this is a far lower standard than we want for articles, but I hope it will be a useful start here. Andrewa (talk) 21:29, 9 June 2012 (UTC)

Collector

A technical term particularly in the USA. Can mean the whole of an extractor manifold, or just the part of it that combines the exhausts from several cylinders. May also mean any multicylinder aftermarket or performance manifold whether or not with any extractor function. Andrewa (talk) 19:41, 8 June 2012 (UTC)

Exhaust manifold

As a technical term, the part of the exhaust system that attaches immediately to the engine, whether single cylinder [34] or multiple. It may attach to the cylinder head or, in the case of some two-stroke engines and flathead V8s and possibly others, to the cylinder or cylinder block.

As a descriptive phrase, the part of the exhaust system that combines the exhaust from several cylinders. Andrewa (talk) 19:41, 8 June 2012 (UTC)

Expansion chamber

As a technical term, refers to the tuned exhaust of a two-stroke engine, and possibly has other technical meanings in pumping stations and the like.

As a descriptive phrase, refers to the part of the two-stroke tuned exhaust system that functions as a Helmholtz resonator, and has several other meanings including parts of other exhaust systems. Many mufflers function as expansion chambers, as do parts of some scientific instruments. Andrewa (talk) 20:42, 8 June 2012 (UTC)

Extractor manifold

Also commonly called extractors.

In Australia, strictly this is an exhaust manifold that uses the Venturi effect to scavenge one cylinder using the exhaust of another. Unsure whether a tuned zoomie header qualifies, I guess it could. Andrewa (talk) 19:41, 8 June 2012 (UTC)

Header

US English. Any exhaust manifold other then the plain cast-iron ones that come on many engines, with or without extractor function [35]. Andrewa (talk) 19:41, 8 June 2012 (UTC)

Tubular manifold

UK English. Similar to header. Andrewa (talk) 19:41, 8 June 2012 (UTC)

Tuned exhaust

As far as I know this is just a descriptive phrase rather than a technical term. As such, it covers both the tuned exhaust systems used on two- and on four-stroke engines, despite them working on very different principles. Andrewa (talk) 21:35, 9 June 2012 (UTC)

Tuned pipe

As a technical term, similar to expansion chamber, and may also have other meanings in automotive engineering, in music and in acoustics.

As a descriptive phrase, any resonator whose frequency is determined by the length of a column of air or other gas.

Its technical usage applied to two-stroke engines is therefore a misnomer, but it is an accurate description of the tuned exhausts used on four-stroke engines. Andrewa (talk) 01:18, 9 June 2012 (UTC)

Other articles

I've had a go at populating Category:Exhaust systems. Several of these were not previously in it [36] [37] [38] [39] [40].

And another [41]. Andrewa (talk) 21:00, 13 June 2012 (UTC)

Below is a survey of those articles on exhaust systems, tuned or otherwise, that I've found so far.

• Expansion chamber - two-stroke systems only. Multiple issues.
• Tuned pipe - subset of the material at expansion chamber, see Talk:Tuned pipe#Proposed redirect.
• Exhaust pulse pressure charging - supercharged two-stroke loop-scavenged diesels.
• Kadenacy effect - stub article on patented use of exhaust momentum to draw new charge into the cylinder or combustion chamber, applied to various internal combustion engines including two-strokes and pulse-jets.
• Exhaust system - four-stroke systems only (!), other issues.
• Exhaust manifold - four-stroke systems.
• Scavenging (automotive) - marked as stub.
• Aftermarket exhaust parts - looks to be comprehensive coverage, some refs but many more needed.

And of course tuned exhaust needs more refs too. Most of them do. Lots still to do. Andrewa (talk) 22:09, 10 June 2012 (UTC)

Add

• Pressure wave supercharger - fascinating and well referenced, could use a tidy up.
• Inertial supercharging effect - A stub with issues, the lead talks about valve timing but the body is a single paragraph about two-strokes which is well worth a read: The inertial supercharging effect from two-stroke engines is the result of the design of an expansion chamber in the two-stroke exhaust system. Its spiraled inside design was designed to turbulate the exhaust gas and create a vacuum that rips the exhaust gas out of the engine, bringing engine on to a "powerband" in high load situations. As every action has a reaction, by ripping the exhaust gasses out of the engine combined with the effects of the reeds, you are in turn ripping more fuel-air mixture into the combustion chamber, creating a supercharged power delivery effect IE "powerband". This is why the two-stroke engine is preferred by many motorcycling enthusiasts world wide.

Whew! Andrewa (talk) 20:13, 14 June 2012 (UTC)

Article scope and naming

The thing that really strikes me about that survey is that several articles have titles that don't match their current scopes. The most spectacular example is exhaust system, which is currently about four-stroke engines only.

This is an issue that has already led or at least contributed to much grief and misunderstanding at Talk:Expansion chamber and Talk:Tuned pipe. The scopes of the articles didn't (and still don't) match the titles.

Ideally three things need to match:

• The article title.
• The article contents or scope.
• The lead.

If any of these three is out of step with the others, then we have a problem. Andrewa (talk) 12:52, 11 June 2012 (UTC)

Add

• Two-stroke power valve system
• Four-stroke power valve system

to the list... but in both of these cases the title, scope and lead seem to match fairly well. That's not to say either is a perfect article, just the particular issue of scope and naming is not a problem. Also, they both seem long enough that merging to other articles is not likely to be a question. Andrewa (talk) 21:00, 13 June 2012 (UTC)

Progress

I've had a go at the lead of expansion chamber [42] see Talk:Expansion chamber#Lead. Andrewa (talk) 18:34, 13 June 2012 (UTC)

Also added some Wikiproject banners to several talk pages including this one and the exhaust systems category talk [43] [44] [45] [46] [47] [48].

Help of course appreciated, that's the whole reason for adding the Wikiproject banners! Andrewa (talk) 18:53, 13 June 2012 (UTC)

Tuned exhaust of a turbo diesel

http://www.a1customs.com/tuned_performance_exhaust_gm-65_exhaust_system.htm reads in part GM 6.5 Turbo Diesel Performance Tuned Exhaust Systems High-Performance Exhaust System, Mufflers & Special Pipes. Copyright © 1994-2009. The 6.5 stock exhaust system can be improved dramatically by removing the catalytic converter or "soot trap" and in some cases the factory turbo downpipe is dented or crushed looking and very restrictive. You may want to check local regulations before removing the cat. conv. but being a diesel in some areas this 'may' be allowed... (their formatting removed and my emphasis added).

There's no mention of why they call these exhaust systems tuned, and I'm skeptical of many parts of this page. In terms of this article and any sensible definition, these exhaust systems don't appear to be tuned at all. At best they seem to be tuned only in the sense of being part of a package to increase engine performance. But this isn't the place to indulge in original research concerning the validity of the claims of advertisers.

On the other hand, if the claim that these systems are tuned is in some sense valid then that information belongs in the article.

Either way in fact, if reliable sources can be found to either support or dismiss the claim that these systems are tuned then that information could well be encyclopedic, and a very interesting addition to the article. Andrewa (talk) 21:11, 13 June 2012 (UTC)

Sources

Scientific Design of Exhaust and Intake Systems (Engineering and Performance) [49] looks very interesting. One review reads in part This book is one of only a few in this field [50] which is my experience too! This review continues to suggest better references as AG Bell's books or Dalton's "Practical gas flow" which he says are more up to date. Andrewa (talk) 19:51, 4 December 2012 (UTC)