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Thread: Oddball engines and prototypes

  1. #1651
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    From Ricardo's experiments with two stroke sleeve valves:

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    Lohring Miller

  2. #1652
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    Quote Originally Posted by husaberg View Post
    EN10

    it may not have been arround then? but i doubt it it looks like just a plain carbon steel?
    Looks the same, it's just an absolute bitch to machine.
    Go soothingly on the grease mud, as there lurks the skid demon

  3. #1653
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    Buried under a pile of *yger

    Quote Originally Posted by Pursang View Post
    Quote Originally Posted by wobbly View Post
    There are some very knowledgeable people out there that completely disagree with Me, Frits and Jan about the Ex duct cooling principle.
    Roland Holzer in his last iteration of the Modena kart engine made the duct alot shorter, saying that this allowed the pipe ( header,spigot ) to heat up faster
    when exiting corners.
    Franco at TM has a radical new design in CAD that completely insulates the duct from water cooling with an air gap.
    I plan on completely disproving the whole hot duct idea ( or making an idiot of myself ) by very soon having a brand new TM cylinder ceramic coated inside the duct.
    This coating surface will be VERY hot where in contact with the retained air/fuel charge.
    Doing exactly this process on the Britten made a heap of power, and doubled the water boil time when the bike was warmed up ( as the small rad was ducted correctly
    for forward motion,not sitting still ).
    It will have only one of two results on the 2T - 125 , instant detonation due to overheated gas being pushed back into the cylinder, or the engine will make more power due to
    more heat energy being transferred into the pipe.
    Just a very small maybe - would be both effects occur simultaneously. But deto kills engines,so that trumps the other effect every time.
    The dyno will not lie,as will the deto sensor on the head.
    Even if I am wrong I WILL tell everyone the result,as it has caused some very heated ( pun intended ) discussion, with lots of Italian arm waving in the process.
    And of course I would REALLY love to finally prove that The Great Leader was talking out his arse about a hotter duct being better - though he sort of already did that with
    his Chinese funded fiasco.
    With a bit more than an academic interest in exhaust duct cooling, I'm very interested in the potential value of a ceramic coated duct.

    https://s3.amazonaws.com/WEBPOSTS/KI...t+duct+Std.jpg

    In my simplistic approach to these things, it looks to me the the only real advantage to extensive water-cooling of the transfer duct is to provide thermal stability.
    Thus enabling "careful tuning" to control the point of detonation.

    The Negative to this heavy temperature management is removal of heat/energy from the exhaust pulse and the addition of heat to the charge in the duct.
    Plus the need to dispose of the captured (& wasted) heat/energy.

    As it has been determined, polishing the piston face, allows it to reflect, rather than absorb the heat of combustion.

    It follows (to me) that polishing the duct and header pipe should produce a similar result.
    Allowing hot exhaust to pass through without depositing heat AND allow cool transfer charge to enter and leave without picking up extra heat (Win-Win?)

    Polishing ducts and headers could, perhaps, also be simulated by a process something like this...
    .
    https://s3.amazonaws.com/WEBPOSTS/KIWI+ESE/jet+hot.JPG

    It's smooth & shiny, contains silver and is highly heat reflective.
    It is claimed to reduce the external temperature of headers by around 150C. AND that's After heating the steel tube from the inside.
    So the heat reflection is internal at the steel to coating junction. Heat reflection without the physical conduction could/should be much higher(?)

    (It is possible the inside was coated too, other coating companies suggest that they do it that way)
    .
    https://s3.amazonaws.com/WEBPOSTS/KI...hreduction.jpg

    Might be just speculation & wishful thinking......or the next Great Step Forward in 2 stroke technology & performance.
    This didn't get a single response on ESE, (even though it directly related to a Wobbly post). Not even a derogatory slur.
    The ESE Focus is obviously in a different direction at the moment.

    Perhaps the Learned Gentlemen that visit here, might have some experience, information, feedback, comment.

    cheers, Daryl

  4. #1654
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    Well I've learned that you don't mirror finish inlet ports as it will actually reduce flow...For max flow, there should be a boundary layer. A finish equivalent to a light hone or bead blasting is sufficient to give the boundary layer something to form on. How this would equate to a high velocity, high temp exhaust which will have a lot of energetic tumbling motion entrapped in it, i really can't guess.
    Irving, as always, had something to say about exhaust ports - a thin layer of carbon is a good insulator....
    I will no longer see PM's on this a/c. If you wish to PM me, use grumphv2 a/c please - and include an email address if you require a reply.
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  5. #1655
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    MY take is, how often are you going to re polish this duct? I can't see it staying shiny for very long at all.
    Neil

  6. #1656
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    Quote Originally Posted by Grumph View Post
    Well I've learned that you don't mirror finish inlet ports as it will actually reduce flow...For max flow, there should be a boundary layer. A finish equivalent to a light hone or bead blasting is sufficient to give the boundary layer something to form on. How this would equate to a high velocity, high temp exhaust which will have a lot of energetic tumbling motion entrapped in it, i really can't guess.
    Irving, as always, had something to say about exhaust ports - a thin layer of carbon is a good insulator....
    I read something years ago about NASA researching what you might call variable texture surface corrugations, trying to match optimum boundary sheer profiles with actual flow velocity.

    Sounded far too advanced for any technology I could imagine at the time, but one of the research strings involved dolphins. Their subcutaneous fat ripples as they swim, and the ripples apparently very closely resemble the perfect pitch/texture to minimise drag at any given speed.

    There's been at least one elastomeric tube developed in an attempt to mimic that effect.
    Go soothingly on the grease mud, as there lurks the skid demon

  7. #1657
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    I don't know about the exhaust surface finish, I have always made the inside of the model engines in the 400 to 600 grit finish range, so quite smooth but not shiny. Anyway's many years ago, a guy in Hamilton a Ferrari that they decided to polish the insides of the inlet ports when they did some work on the heads and valves. It went noticeably worse due to the polish work they did. I am not sure if they got the inlets lightly sand blasted again or not. Somewhere on here at KiwiBiker, was mention of a 400 grit surface finish for inlet ports. Can't remember who said it though.
    Neil

  8. #1658
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    Quote Originally Posted by Ocean1 View Post
    Looks the same, it's just an absolute bitch to machine.
    i was meaning from the look of the basic use spec sheet
    it has Si and Ni is that what makes it harder to machine or does it tool harden?
    Quote Originally Posted by Ocean1 View Post
    I read something years ago about NASA researching what you might call variable texture surface corrugations, trying to match optimum boundary sheer profiles with actual flow velocity.

    Sounded far too advanced for any technology I could imagine at the time, but one of the research strings involved dolphins. Their subcutaneous fat ripples as they swim, and the ripples apparently very closely resemble the perfect pitch/texture to minimise drag at any given speed.

    There's been at least one elastomeric tube developed in an attempt to mimic that effect.
    shark skin as in the swimers togs to replicate a sharks skin.
    http://www.symscape.com/blog/swimsui...hnology-doping
    http://theconversation.com/fast-suit...n-records-7960
    Golf balls is another. although a little more complicated.
    http://www.aerospaceweb.org/question...cs/q0215.shtml
    I polish exhaust ports on 2ts as i can;t be arsed removing carbon later.
    Quote Originally Posted by Lightbulb View Post
    lightly sand blasted again or not. Somewhere on here at KiwiBiker, was mention of a 400 grit surface finish for inlet ports. Can't remember who said it though.
    Neil
    dremel finish flatted off with 400 git is perfect according to Jan? i think.

    Quote Originally Posted by lohring View Post
    From Ricardo's experiments with two stroke sleeve valves:

    Click image for larger version. 

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    Lohring Miller
    nice find.Ricardo was years ahead of himself even with tapering of ports as well as 4v and squish turbulence too
    But in modern terms #The coolant temp should not be allowed to get anyhere near 100C on a competition engine esp a two stroke.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  9. #1659
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    Wonder if this goes any better than anything else? Would take a few hours of CNC programming..


    Click image for larger version. 

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    “The only reason for time is so that everything doesn’t happen at once”

  10. #1660
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    The only positive story I know about mirror finishing inlet ports relates to the Suzuki GSXR750J. It was supposed to be the ultimate in that family, shorter stroke, bigger valves, bigger ports...
    Flowbench and dyno work showed that the inlet ports in the casting were too big. AMA rules said you couldn't add material..
    By mirror finishing the inlets a turbulent boundary layer formed. Apparently the mirror finish gives a sort of grip and release effect on air passing which makes for a turbulent layer.
    The thick turbulent layer had the effect of reducing the cross sectional area of the port...job done.

    That head has become a favourite of the US drag racers for fitting to the old air cooled GSX1100, bolts straight on , just block the oil drains.
    I will no longer see PM's on this a/c. If you wish to PM me, use grumphv2 a/c please - and include an email address if you require a reply.
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  11. #1661
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    Quote Originally Posted by husaberg View Post
    i was meaning from the look of the basic use spec sheet
    it has Si and Ni is that what makes it harder to machine or does it tool harden?
    Oh aye. Well it's almost all carbon steel, even mild steel has a bit, just not enough to harden.

    Anything with Si is hard on tools, which nowadays usually means carbides, which often means compromising tool profiles. High Ni content steels tend to high sheer strengths, which means they tear easily. Well, not easily, in fact it takes a bit of grunt but it seems to like bonding to the tool surface, so it tears rather than sheering nice and cleanly. So without razor sharp edges, a nice rigid setup and a decent coolant you get jagged finishes, especially screwcutting and similar.

    High manganese stuff can be a pain too but my favourite thing to bitch about having to machine is AB2. I took some castings to a local who had a big fuckoff Toss horizontal borer, ('cause I didn't want to spend forever doing the job on my universal). His machine wouldn't think anything of driving an 80mm 6 tip face cutter at 10mm x .5 cuts in 316, but the best he could do on that stuff was 2mm x .2. He's been deeply suspicious of every job I've taken there ever since.
    Go soothingly on the grease mud, as there lurks the skid demon

  12. #1662
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    Quote Originally Posted by ken seeber View Post
    Wonder if this goes any better than anything else? Would take a few hours of CNC programming..


    Click image for larger version. 

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    I can imagine. Any idea what they used to cut it?
    Go soothingly on the grease mud, as there lurks the skid demon

  13. #1663
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    Quote Originally Posted by Grumph View Post
    Well I've learned that you don't mirror finish inlet ports as it will actually reduce flow...For max flow, there should be a boundary layer. A finish equivalent to a light hone or bead blasting is sufficient to give the boundary layer something to form on. How this would equate to a high velocity, high temp exhaust which will have a lot of energetic tumbling motion entrapped in it, i really can't guess.
    Irving, as always, had something to say about exhaust ports - a thin layer of carbon is a good insulator....


    Not too concerned about flow,at the moment. (Seems like every discussion about this subject, out there, is always about the Flow)

    Limiting/minimising heat transfer, into (and out of) the exhaust port walls, is the goal. Whatever works best, be it silver mirrors, refractory ceramic or carbon crust.

    Perhaps a little bit of high school Physics.

    Click image for larger version. 

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    Of these 3, Forced Convection is the source of our heat energy (in the port & header).

    IR Radiation: (Waves not particles)

    Dull surfaces are good absorbers and emitters of infrared radiation.
    Shiny surfaces are poor absorbers and emitters (but they are good reflectors of infrared radiation)

    Conclusion: Dull, Matt surfaces are best at taking heat from the exhaust gas AND transferring that heat to the cooler fresh charge.

    Conduction: (Fast molecules smashing into Slower molecules )

    A vacuum is the best conductive insulation, no particles to transfer the energy.
    Air gap is an alternative. The High Temp surface coatings consist of hollow ceramic nano balls, to provide the air gaps.

    Conclusion: A shiny smooth reflective surface finish with insulating ceramic nano balls might be a good way to avoid taking heat from the exhaust gas and NOT transferring that heat to the cooler fresh charge. Maybe???

    And this might be why simply a polished surface OR a ceramic coated one are (reportedly) not, on their own, notably effective.
    The result of combining the two might be greater than the sum of the parts. (like a Vacuum Flask)

    Cheers, Daryl.

  14. #1664
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    Quote Originally Posted by Lightbulb View Post
    MY take is, how often are you going to re polish this duct? I can't see it staying shiny for very long at all.
    Neil
    Burn marks (carbon) form where the raw fuel meets a surface that is above its ignition temperature.

    That's Exactly what I'm trying to avoid by limiting exhaust heat transfer.

    Besides My engine doesn't need to run for hours between pull downs.

    Cheers, Daryl.

  15. #1665
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    Quote Originally Posted by Grumph View Post
    The only positive story I know about mirror finishing inlet ports relates to the Suzuki GSXR750J. It was supposed to be the ultimate in that family, shorter stroke, bigger valves, bigger ports...
    Flowbench and dyno work showed that the inlet ports in the casting were too big. AMA rules said you couldn't add material..
    By mirror finishing the inlets a turbulent boundary layer formed. Apparently the mirror finish gives a sort of grip and release effect on air passing which makes for a turbulent layer.
    The thick turbulent layer had the effect of reducing the cross sectional area of the port...job done.

    That head has become a favourite of the US drag racers for fitting to the old air cooled GSX1100, bolts straight on , just block the oil drains.
    My understanding of that model was it was fine on the road and gave more power then the previous model but when modified and used with longer duration cams then the std road ones the package never worked as good as the old motor did when modified. it was a bridge to far.
    Pretty sure the later suzukis sprads with improved heads and tech went back to the same short stroke bore stroke ratio years later with no issues.
    Your comment made me think of when Muzzy got pinged one year in the Scott russell/Gobert WSB era for running a device that made the FCR41 into 39mm carbs.
    They had got away with it all year, as they designed them to stay attached to the intake manifold this was allowed but one day at tech inspection they came appart with the carbs.
    so they had to fidlle them back in.
    I think they used them at almost all tracks. likely for the same reason the Suzuki never worked properly.
    I think the rules then were std carbs and gearbox and rod material which was why the OWO1 and the ZXR750RR had the CR box and slide carbs and the Ti rods.
    That said it must mean the the RC30 won all its races on race kitted CV carbs because thats what they had std so thats pretty impressive in hindsight.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

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