Talk:Bourke engine/Archive 3

25th Jan references
sorry i've screwed up the refernence names, I'll work on them today. In February I will delete or edit all statements with reference requests that have been outstanding for more than a month. ALL.Greg Locock (talk) 21:26, 24 January 2008 (UTC)

One stroke two stroke 4 stroke or 8 stroke ?
Well, it is make your mind up time. From the description given of the cycle it is clearly a two stroke in my opinion. Greg Locock (talk) 04:26, 19 January 2008 (UTC)

January 17th 2008
On Jan 17 I shall be deleting all unreferenced statements that have been flagged, adding flags as needed and generally cleaning the article up. Thereafter I will regard the Jan 17 version as the default unless further claims are referenced properly. If you have any unreferenced claims in the article make sure they are tidied up by then. Greg Locock (talk) 10:17, 13 January 2008 (UTC)

To "Enthusiasts" Please refrain from personal attacks
I have noticed personal attacks posted in the article. Please do not post them in the article. It does not help your credibility, the credibility of your arguments, or contribute to the wikipedia in any way. —Preceding unsigned comment added by 64.146.239.67 (talk) 16:27, 4 January 2008 (UTC)

???????????????????????????????????????????????????????????????????????????????????????????????? —Preceding unsigned comment added by HemperorOfSmokeLandVillez.dum (talk • contribs) 15:56, 14 January 2008 (UTC) Huh ??? Did you act WRONG by THINKing that ONLY-YOU aRe the Russell Bourke-Cycle-Engine "Expert" ??? Wikipedia should BAN you because you kept claiming that Russell Bourke's engine make's Nitrogen DiOxide and that IS TOTALLY FALSE. Know yor chemistry. Catalytic converter's are ONLY needed when POISON is PRODUCED. Know your chemistry, so said Ru$$ell Bourke, the Je$u$ Chri$t of Internal-Combu$tion ...... - Hemperor that LOVE'$ www.RogerRichard.com 's expo$ure of the TRUTH a$ of 1-14-2008AfterDope 10:55am

Patents
I see no point in trying to add useful info to this article since it is being continuously vandalised, but if snybody cares heres a link that details the patents http://peswiki.com/index.php/Bourke_engine. As usual the nutjob is wrong. Greg Locock (talk) 03:55, 4 January 2008 (UTC)

???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? What NutJob iz wrong ? YOU ??? Again ??? Which Patent of Russell Bourke's design are you concerned with ??? Russell didn't have as many as Nikola Tesla, but he had several. Some weren't even filed, like his triple-slipper-bearing design as required for long term non-failure ...... WHY iz the Bourke Engine Documentary information BADLY-WRONG to GregyzLowCock ??? Doe$ the TRUTH HURT ??? your profit'$ ??? - Hemperor 1-14-2008AfterDope 11:04am

Jan 2 edits
I see that one of the enthusiasts has been editing again. I am loathe to simply revert it back to the last sane version, without at least discussing whetehr there is any validity to any of the edits.

Is there?

And why has he wrecked the formatting? and deleted the reflist? is this just vandalism?

Greg Locock (talk) 03:24, 2 January 2008 (UTC)


 * OK I've been through it and kept the little that was usable. Note that there are a large number of cites required. Greg Locock (talk) 05:36, 3 January 2008 (UTC)


 * Let's say that ALL uncited statements ned to have cites put in within two weeks. These need to meet WP:RS Greg Locock (talk) 06:54, 3 January 2008 (UTC)

huh ??? Why you allow Russell Bourke to make NO NOx ???
I'm suprised you read about Russell Bourke and what he designed, Mizz GregLoCocker. Why do you not dare call Roger Richard ??? Your BO$$ won't allow you ??? Ain't the TRUTH HURT-FULL ??? Why you call me funny name'z ??? Call me Nitrous-DiOxide_Breather ...... but homebrew homegrown Carbon-DiOxide iz a better DeOxygenated BUZZ ..... try it. Make sugar-water and add yeast. Breath in the Yeast-Exhaust and ENJOY the FREE BUZZ ...... Doktor'z like Nitrous and I prefer CarbonDiOxide Yeast Fart'z better than their ALCOHOL-PI$$ ..... ain't life WIERD ??? Or iz it ju$t me in ME ???

I explained why I didn't call Roger on your talk page. In addition I found some old correspondence with him from several years back. He was asked by several engineers why he didn't do some proper measurements on the engine and he came up with the usual guff. SO there is no point talking to him. He won't do the only test that will give the engine any credibility. That is his choice, but I see no point in repeating our advice to him.Greg Locock (talk) 04:45, 4 January 2008 (UTC)

???????????????????????????????????????????????????????????????????????????????????????????????? You did NOT remember typing at the www.RogerRichard.com guy that followed proof on paper and got proper result's after MANY learning bump'z ??? When you don't have many "copie's" of your proper design, why murder it without making a "clone" first ??? Where is YOUR test equipment ??? Can it test my Father's 9,000 pound-rated rotor-head bearing with-out ANY DOUBT of "your" result's ??? What if the "factory" was sold SOFT-METAL ??? SUE-WHO ??? You ??? GregysLowCock doesn't dare to talk with a Vietnam Veteran that know's how to trick ScarePlanes into crashing into mountain's ??? The ScarePort beeper iz right on top of that hill ...... 1-14-2008AfterDope 11:15am (ECT-5)

NPOV
Would whoever slapped a NPOV tag on the article on 11 December like to explain whether they are of the opinion that it reads too much like a credulous piece of PR, or is an over-enthusiastic demolishment of said puffery (with references?). Otherwise I'll take the tag off in mid January. Greg Locock (talk) 20:26, 31 December 2007 (UTC)

Creditable Witness
Greg, It seems that my computer has been infected with SpyWare from Argentina... Did you install SpyWare on my computer?--Alexfine (talk) 23:18, 9 December 2007 (UTC)


 * No Greglocock (talk) 00:44, 10 December 2007 (UTC)

Greg, I have copies of letters from military Generals and Majors that have witness the Bourke Engine operation. In their letters they have stated observations of (felt) low exhaust temperatures, light weight engine, and few moving parts. Would you like me to fax you copies of the letters. Also, I have copies of the Hot Rod magazine engine journalist article(s) that have witness the engine run continuously for hours, light weight, few moving parts, high power, and low fuel consumption. Would you like me to fax you copies of the articles?

Someone has published Paul Niquette account of an engine that someone (or he) claims to have been a Bourke Engine or replicate. His account doesn’t reflect any of the accounts I have read by military leaders or of the engine journalist. But, sounds like an account of other type of opposing piston engine. He does not represent a creditable agency for engine testing. His information needs to be removed from this web-site. He is not a creditable witness his resume reads like a rap sheet.

http://www.niquette.com/paul/access/resume.html

The Bourke is a unique engine no engine in the world runs like the Bourke engine. If you can provide information that differs, or of other engines that run like the Bourke please forward links. What is your definition of constant volume?

Who deleted my discussions? --Alexfine (talk) 01:46, 9 December 2007 (UTC)

I archived the previous versions of this page, see the panel at the top right.


 * I'll fax in a couple days. --Alexfine (talk) 21:33, 9 December 2007 (UTC)


 * Four days later, no fax. Gosh I'm surprised.

The fact that you don't like Niquette's report is neither here nor there, but if the Hot Rod writeup includes test results that are better then we'll stick them in the article.


 * Niquette, contains no facts just an account there are no vidoes, photos, data, or POC for the engine witness. His account needs to be removed.--Alexfine (talk) 21:33, 9 December 2007 (UTC)


 * Which are precisely the objection to the Bourke engine website, video proves little. We need authenticated numbers, not photos or videos.

I notice you are editing this page using several different accounts. If you have any connection with HemperorOfSmokeLandVillez.dum?, I suggest that you get him to calm down, as he is one tiny step away from being banned. I'm going to ask the admins to semi-protect this article so that only established editors (including you) can edit it. But please don't try and include uncyclopaedic stuff like 'The Bourke is a unique engine no engine in the world runs like the Bourke engine.'


 * Please provide links to other internal combustion engines that use the Scottish Yoke. Otherwise, the reference of the Bourke Engine is ‘unique’ is a true.--Alexfine (talk) 21:33, 9 December 2007 (UTC)


 * Five minutes googling: http://www.sliderengine.com/
 * http://www.rotoblock.com/howitworks.shtml
 * http://www.carjunky.com/Concept_Cars/Concept_Engines/Research/Scotch_yoke_engine_improvements_L37546/
 * http://www.jonfry.com/2005/06/stuttgart-sees-launch-of-extraordinary.html
 * etc. Face it Scotch yoke has been around for more than a hundred years and has a hundred years of cranks haha who like it.

Constant volume combustion means that the exploding mixture is held at a constant volume while it burns. You can't do this in an engine with a crankshaft, and the Scotch Yoke does offer a slight improvement over a conventional engine in this respect. However the difference is tiny. You can work it out yourself, since you are an engineer.


 * Thanks, I'll use the fact the Scotch Yoke offers some slight improvement over an engine with crankshaft.--Alexfine (talk) 21:33, 9 December 2007 (UTC)


 * Yup, grasp at any straw. That is the sure sign of an engineer (sarcasm). Work the numbers out yourself. Greglocock (talk) 12:11, 13 December 2007 (UTC)

Greglocock (talk) 02:31, 9 December 2007 (UTC)

Problems with the second opinion of the critique
1) Seal friction from the seal between the air compressor chamber and the crankcase, against the conrod, will reduce the efficiency. - Opinion 2nd: The crankshaft revolves within the Scottish Yoke there is no connection to the piston rod to restrict motion, during critical timing operations.


 * This is the seal that prevents the charge from getting into the crankcase. Does it rub against the conrod? Yes of course. Does it create friciton? Yes of course

2) Pumping losses, the air charge is compressed and expanded twice but energy is only extracted for power in one of the expansions. – Opinion 2nd:: There are two compression strokes for every revolution of the crankshaft twice the power.


 * No, this is the standard problem with a two stroke that uses transfer ports- first you draw the air into the first chamber, then you compress it, then transfer it via the transfer ports, and expand it and then you have to compress it again.

3) Engine weight is likely to be high as it will have to be very strongly built to cope with the high peak pressures seen as a result of the rapid high temperature combustion, and the scotch yoke/triple slipper bearing are heavier than a conventional crankshaft. – Opinion 2nd: Prototype engines demonstrate light weight, proven.


 * What power to weight ratio has been achieved?

4) Each piston pair is highly imbalanced. This will limit the speed range and hence the power of the engine, and increase its weight due to the strong construction necessary to react the high forces in the components. – Opinion 2nd: Videos of the Bourke engine demonstrates balanced engine and smooth operation. Opposing piston engines are used in motorcycle engines today, proven


 * Boxer two cylinder engines move both pistons inwards together, so they balance each other. A Bourke two cylinder moves the pistons in the same direction, so there is no counterbalance. An 8 cylinder Bourke (4 pairs of pistons) would be balanced, anything less is not.

5) High speed two-stroke engines tend to be inefficient compared with four-strokes because some of the intake charge escapes unburnt with the exhaust. – Opinion 2nd: The different Bourke engine videos do not show any visible emissions (gaseous) directly from the exhaust port, good indication of complete combustion.


 * You don't measure efficiency by /looking/ at the exhaust gas. You measure the amount of fuel in, and the energy you get out.

6) When the charge is transferred from the compressor chamber to the combustion chamber it will cool down, reducing the efficiency of the engine. – Opinion 2nd: The ideal gas law proves that temperature, volume, and pressure are proportional, proven.


 * Sorry that is not what is being discussed.

7) Use of excess air will reduce the torque available for a given engine size. – Opinion 2nd: Excess air insures completed combustion will occur and that all the hydro-carbons (fuel) ignite. Excessive air (oxygen) has been proven in turbo charged engines to increase power, proven.


 * Rubbish, for maximum power for a given swept volume you need a slightly rich mixture.

8) Forcing the exhaust out through small ports will incur a further efficiency loss. – Opinion 2nd:: No studies or proof demonstrate this is ineffective, but is unique to the Bourke Engine.


 * No, this is a standard feature of every internal combustion engine. I do agree that it is not necessarily worse on the Bourke than on other engines

9) Operating an internal combustion engine in detonation reduces efficiency due to heat lost from the combustion gases being scrubbed against the combustion chamber walls by the shock waves. – Opinion 2nd:: The Bourke Engine can handle detonation because of is unique piston design. View prototype engine, and listen to the little bombs exploding.


 * I'm not too sure about this one to be honest. However if the claim is correct then your answer doesn't counter it.

10) Emissions - although some tests have shown low emissions in some circumstances, these were not necessarily at full power. As the scavenge ratio (ie engine torque) is increased more HC and CO will be emitted. See HCCI engine. - Opinion 2nd: Tested were performed at different RPMS (engine torque), by Roger Richards.


 * well great lets see some test results.


 * Greglocock (talk) 03:53, 9 December 2007 (UTC)

Efficiency calculations
For 1 hp burning 1 lb/h of standard gasoline.

calorific value		4.27E+07	J/kg 1 lb/h	=	0.454	kg/h fuel energy in per hour=		1.94E+07	J/h Therefore power in=		5385	W

power out	=1 hp=	745.7	W efficiency=power out/power in=		13.85% Greglocock 08:36, 27 June 2007 (UTC)

Operating Cycle
(0)Starting from BDC the intake port is covered. As the piston travels toward TDC energy is used to create a partial vacuum in the compression (lower) chamber. As the piston approaches TDC the intake port is opened and air is drawn into the compression chamber from the intake duct. The energy used to create the vacuum cannot be recovered as the air transfer is an irreversible process.

(1) TDC, with a full charge of air in the compression chamber, the cool air is warmed by the cylinder walls and piston.

(2) The piston moves down, so the skirt closes the intake in the beginning of the down stroke. The air is then compressed by the piston, its temperature and pressure rising roughly in an adiabatic compression. In the early stages of compression it absorbs heat from the cylinder walls. In the later stages of compression it warms the cylinder, resulting in a loss of internal energy (This is inevitable according to second law of thermal dynamics regarding energy transfers). Some of this heat is also lost to the cooling system. Given the extended dwell time around BDC this heat loss to the walls is greater than a more conventional two stroke.

(3) Approaching BDC the piston uncovers the transfer port and opens the exhaust port of the combustion chamber. Energy stored in the compressed air in the compression chamber is used to help blow the exhaust out of the exhaust port. As it does so the compressed air expands and cools some and fuel is injected and mixed with the incoming charge. As in a traditional cross-scavenged two stroke engine, inevitably some mixing of the incoming mixture and the exhaust takes place. If the scavenge ratio exceeds 40% some fresh mixture is discharged unburnt out of the exhaust port.

(4) At BDC the residual exhaust in the chamber and the walls of the chamber heat the incoming mixture.

(5) As the piston moves up the piston ring closes the transfer port in the combustion chamber and the exhaust port. As the piston moves up the bore it re-compresses the mixture causing it to heat up and transfer heat back into the walls. As in (2) the heat transfer to and from the mixture increases the internal energy loss from the mixture. Also as in (2) some of this heat lost to the walls is lost to the cooling system. Since the Bourke engine has extended dwell time near TDC the air charge is held in a compressed heated state, exacerbating the heat loss to the walls.

(6) TDC - the mixture is fully compressed, and is now ignited, either by self ignition or by the spark plug. If the mixture detonates it will cause shock waves to bounce around the combustion chamber. Each time these shock waves bounce off a wall or the piston the compressed charge forming the shock wave transfers heat to the piston or combustion chamber wall losing energy that otherwise could be extracted in the power stroke.

(7) The rising pressure due to the combustion forces the piston back down the bore. Since the burning/burnt mixture is hot it heats the cylinder walls. The extended dwell time around TDC ensures almost complete combustion of all the fuel. However as in (5), the extended dwell time also increases the amount of heat transfered to the walls which is later lost to the cooling system.

(8) The piston ring uncovers the transfer port and the exhaust port (as in 3), and the exhaust flows out of the exhaust port, pushed out partly by the incoming charge.

--DieselDude 01:33, 28 June 2007 (UTC)


 * This operation mostly a two stroke cycle. I don't think it belongs in this article. There are some minor differences and those should be called out where appropriate but the two-stroke lecture is distracting. —Preceding unsigned comment added by War (talk • contribs) 07:32, 14 December 2007 (UTC)

Request for cites
OK, I'm going to do that this afternoon. Greglocock (talk) 01:17, 16 December 2007 (UTC)


 * Done GregLocock 06:49, 16 December 2007 (UTC) —Preceding unsigned comment added by Greglocock (talk • contribs)

Discussion of Conspiracy angle
Why do people associate the Bourke engine with a conspiracy? He died of natural causes and nobody used the design. If there was a conspiracy he would have died prematurely and under unusual circumstances and industry would have snapped up his design. Just look at what happened to Rudolf Diesel. --DieselDude (talk) 00:24, 16 January 2008 (UTC)

Wrong Information
6) When the charge is transferred from the compressor chamber to the combustion chamber it will cool down, reducing the efficiency[citation needed] of the engine.[18]

This is not a fact, it is incorrect. If the author is implying that the cooling decreases the heat of the working fluid then the author should consider that the engine's heat is regulated with cool fuel, air and fluid circulating around the engine, therefore any heat loss is irrelevant as it readily available save material limitations. —Preceding unsigned comment added by 66.186.238.96 (talk) 04:52, 26 October 2008 (UTC)


 * No. That would only apply if there was no heat transfer between the working fluid and the rest of the engine as it was compressed and then expanded. That is called a reversible adiabatic expansion cycle, and is only theoretically attainable, that is, in practice you always lose a bit in each process. This is first year undergraduate thermodynamics.


 * I'd add that the whole reason we split the article up into separate advantages and critique sections was to reduce the schizophrenic tendency that you have reintroduced. To be honest until someone publishes some real performance data for one of these things and runs it for a long time (as for example Revetec has had the guts to do with their engine) then it is a bit of a waste of time arguing the fine points of this stuff. For the record, you are definitely wrong on the balance, anything less than an 8 cylinder (ie 4 module) engine will be unbalanced unless you add external balancer shafts, you appear to be ignoring the first order torque effect due to the cylinder spacing. Greg Locock (talk) 07:22, 26 October 2008 (UTC)


 * Item #6 is still incorrect. You are correct isentropic flow is not attainable due to heat escaping. However the compression-expansion-compression is not exactly isentropic http://engr.bd.psu.edu/davej/classes/thermo/Fig6_19.gif nor is anyone implying as much. The heat lost from the working fluid during expansion is radiated back into the working fluid from the engine components that are maintained at a higher temperature. Consequently, the graph would instead increase in temperature from initial conditions. The efficiency loss is zero and potential gains are possible from engine components radiating heat into the cooled working fluid. Imagine the point on the TS graph at a given time, T0 the compression chamber is full dS=0 T0=1, the compression chamber decreases volume ds=~0 T1=2. Heat begins to radiate into the engine at this time T3=1.9 ds=~-0.1. The working fluid is decompressed into the combustion chamber T4=.9 ds=~-0.1. The heat from the engine combustion chamber radiates into the decompressed working fluid T4=1.2 ds=~.2 at a higher rate than the heat escaped due to the hot working fluid evacuated one half cycle prior. The working fluid is compressed T5=2.2 ds=~.2. Pressure loss due to inefficient air seals may decrease the overall efficiency however.


 * You are correct about the balancing for nonconcentric side-by-side piston alignments of the motor, however concentric end-on-end piston alignments are indeed balanced.


 * If the criticism section should contain only criticism and no advantages; the advantage section without criticism, then it would follow that the false and/or irrelevant argument be removed. The remaining true and/or relevant statements would then be sorted into the appropriate section, criticism or advantage. However that may reduce the diversity of information available or increase the quality of the article, I don't know which would occur, what is wikipedia's position on this? Who would determine what is true, false, relevant or irrelevant?66.186.238.96 (talk)


 * "The efficiency loss is zero " Wrong. I wish you wouldn't edit your own points after I have replied to them it makes my observations look irrelevant, although I do understand that you have the right to do that. Can I suggest that you register? The article as it was was the result of a month of protracted argument and vandalism, so I am a bit defensive about how it has ended up. Can I also point out that this article is about the Bourke engine as described in his patents and books, not some potential improved version of the Bourke engine - which would presumably resemble an Orbital Two Stroke? I'll have look through your changes and have a think about how to approach a compromise. Greg Locock (talk) 23:14, 26 October 2008 (UTC)

High Power to weight claim
While it is true that a twin crank arragement will solve the vibration problem it does so at a high cost in terms of packaging space and weight. Similarly the response that high efficiency diesels are heavy doesn't really help, bourke claims high power to weight and high efficiency in the same engine. I emphasise this article is about the Bourke engine and the claims made for it, not some hypothetical improved version.Greg Locock (talk) 00:04, 27 October 2008 (UTC)

Recent edits to criticism section
Rather than get into a silly revert war I'll put them in here, the additions are bolded

1) Seal friction from the seal between the air compressor chamber and the crankcase, against the conrod, will reduce the efficiency . often in a negligible amount when compared to frictional losses due to the high number of moving parts in a typical ICE. 


 * That may be so, but claiming low friction with no proof is just silly - let's see the sums or the tests, it doesn't even need a running engine

3) Engine weight is likely to be high because it will have to be very strongly built to cope with the high peak pressures seen as a result of the rapid high temperature combustion. High pressure diesel engines that obtain similar efficiencies are also overbuilt to withstand the higher stresses often resulting in higher reliability, efficiency and longer service life than other heat engines. 


 * Fine, but that is incompatible with high power to weight ratio

4) Each piston pair is highly imbalanced without another piston pair counterbalancing as the two pistons move in the same direction at the same time, unlike in a boxer engine. . This will limit the speed range and hence the power of two cylinder Bourke Engines, and increase their weight due to the strong construction necessary to react the high forces in the components. Counterbalanced piston arrangements in multiples of four eliminate imbalances, i.e. 4, 8, 12 cylinder motors balancing the motor in a quasi-boxer arrangement permitting high speeds and power ranges for these motors.
 * As mentioned above twin cranks will massively increase the weight, hence hit the power to weight ratio, the 8 cylinder or 4 module unit is the first truly balanced one with a single crank

5) High speed two-stroke engines tend to be inefficient compared with four-strokes because some of the intake charge escapes unburnt with the exhaust. Direct gasoline injection has superseded older fuel delivery systems eliminating this effect, the benefit is most pronounced in two cycle engines. 
 * Firstly the Bourke did not use GDI and secondly the problem is to do with blowdown, not injection. This can be avoided, at a cost in power, and adds a further source of inefficiency (extra scavenge air) but saves blowing partially burnt fuel out the exhaust

6) When the charge is transferred from the compressor chamber to the combustion chamber it will cool down, reducing the efficiency of the engine.


 * I agree this needs a total rewrite, the efficiency problems due to heat transfer are at every stage of the intake, compression and transfer/expansion and recompression cycle. Has Bourke ever published a P-V diagram, either measured or calculated, for the engine?

10) Emissions - although some tests have shown low emissions in some circumstances, these were not necessarily at full power. As the scavenge ratio (ie engine torque) is increased more HC and CO will be emitted. Based on information from non-Bourke Engines.


 * True, but the scavenge compromise is common to all two strokes, it is their defining design issue

9) Operating an internal combustion engine in detonation reduces efficiency due to heat lost from the combustion gases being scrubbed against the combustion chamber walls by the shock waves. 11) Increased dwell time at TDC will allow more heat to be transferred to the cylinder walls, reducing the efficiency. . However excess heat is typically pulled away from an ICE into the atmosphere to prevent damage to the engine, therefore the heat loss is inconsequential to the efficiency.
 * Not true, it is a very important part of the losses,.

'''Furthermore heat may be retained by controlling the amount of coolant flow via a thermostat or other insulation. (Not more so in Bourke's design than in any other, with the exception that the exhaust valve is the biggest single cooling problem (piston is next)). Item 9 is similarly negated.'''
 * No, similarly it is not

12) When running in auto-ignition mode the timing of the start of the burn is controlled by the operating state of the engine, rather than directly as in a spark ignition or diesel engine. As such it may be possible to optimize it for one operating condition, but not for the wide range of torques and speeds that an engine typically sees. The result will be reduced efficiency and higher emissions. Modern ICE components eliminate this criticism because electronic fuel pumps are now the standard on high pressure high efficiency diesel engines that also utilized mechanical fuel pumps prior to emission regulations. The electrical fuel pump allows precise timing and amounts of fuel to be delivered permitting a wide range of high efficiency low emission operating conditions. 
 * Irrelevant because Bourke did not use GDI.

13) If the efficiency is high, then combustion temperatures must be high, as required by the Carnot cycle, and the air fuel mixture must be lean. High combustion temperatures and lean mixtures cause nitrogen dioxide to be formed. The Carnot Theorum specifies that a lower exhaust temperature raises efficiency more than a higher combustion temperature, therefore the low exhaust temperature of a Bourke Engine negates the potential for NOx while providing high potential efficiencies.
 * Possibly, but then the low exhaust temp of the Bourke is anecdotal, and frankly unlikely under power, due to blowdown.

Greg Locock (talk) 23:45, 29 October 2008 (UTC)