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Thread: ESE's works engine tuner

  1. #31711
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    8th February 2007 - 20:42
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    I must say that the so call " Wobbly " exhaust duct parameters are based on square bore/stroke high output engines and thus oversquare
    dimensions will give excessive lengths.
    Lifting the duct floor is only possible once the blowdown has been fully optimised with Aux ports right around to bore center and pin plugs fitted.
    Even then I believe Jan only dyno tested up 3mm in a 54,5 stroke and that is as far as I have dared go.
    The floor should exit perpindicular then form a ski jump slope downward, and flattening asap.
    The roof should exit at 25* then form a radius , reducing in slope.
    This shape tends to equalise the cross sectional area at the point where the side ducts enter the main.
    I have started to think that maybe even attempting a convex roof and or duct floor shape is needed to reduce the area/colume even further.
    Recently I have been testing much larger ( wider ) swooping Aux ducts , and this increases peak and overev power up to a point of diminishing returns
    and then the midrange suffers.
    But of course widening the side ducts increases the area just past the Aux septum ends and on down further to the exit point , making
    this bigger than the 75% rule.
    So further changes to reduce the duct volume need looking at now.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  2. #31712
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    27th October 2013 - 08:53
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    this ktm rad turned out to be the perfect size for what i needed (yes im going to use rubber isolater bushings). brackets are on and old nipples are cut off and plugged. just have to put a couple new nipples on
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  3. #31713
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    14th April 2011 - 23:44
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    Quote Originally Posted by wobbly View Post
    I must say that the so call " Wobbly " exhaust duct parameters are based on square bore/stroke high output engines and thus oversquare
    dimensions will give excessive lengths.
    Lifting the duct floor is only possible once the blowdown has been fully optimised with Aux ports right around to bore center and pin plugs fitted.
    Even then I believe Jan only dyno tested up 3mm in a 54,5 stroke and that is as far as I have dared go.
    The floor should exit perpindicular then form a ski jump slope downward, and flattening asap.
    The roof should exit at 25* then form a radius , reducing in slope.
    This shape tends to equalise the cross sectional area at the point where the side ducts enter the main.
    I have started to think that maybe even attempting a convex roof and or duct floor shape is needed to reduce the area/colume even further.
    Recently I have been testing much larger ( wider ) swooping Aux ducts , and this increases peak and overev power up to a point of diminishing returns
    and then the midrange suffers.
    But of course widening the side ducts increases the area just past the Aux septum ends and on down further to the exit point , making
    this bigger than the 75% rule.
    So further changes to reduce the duct volume need looking at now.
    Making the auxiliary ducts wider than 12mm made less power was my experience

  4. #31714
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    20th April 2011 - 08:45
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    Quote Originally Posted by wobbly View Post
    I must say that the so call " Wobbly " exhaust duct parameters are based on square bore/stroke high output engines and thus oversquare dimensions will give excessive lengths. Lifting the duct floor is only possible once the blowdown has been fully optimised with Aux ports right around to bore center and pin plugs fitted.
    Even then I believe Jan only dyno tested up 3mm in a 54,5 stroke and that is as far as I have dared go.
    Don't let those 3 mm frighten you Wob. Jan had cylinders cast with the exhaust floor more than 3 mm above BDC, but when he realised that he would be in retirement before he would be able to test those, he ground the floors down to the already-tested level before leaving the racing department for good, knowing very well that if these higher floors would have given a positive result after his farewell, some Italian would claim to have 'corrected the errors that Jan Thiel left behind'.

  5. #31715
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    14th April 2011 - 23:44
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    Quote Originally Posted by Frits Overmars View Post
    Don't let those 3 mm frighten you Wob. Jan had cylinders cast with the exhaust floor more than 3 mm above BDC, but when he realised that he would be in retirement before he would be able to test those, he ground the floors down to the already-tested level before leaving the racing department for good, knowing very well that if these higher floors would have given a positive result after his farewell, some Italian would claim to have 'corrected the errors that Jan Thiel left behind'.
    That is true Frits.
    But I had 2 cylinders cast with the bottom of the exhaust as high as the transfers top.
    The last 5 years all our exhaust ducts were CNC machined.
    With many variations!
    During the last year the exhaust bottom was 3mm above BDC.

  6. #31716
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    8th February 2007 - 20:42
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    The 12mm wide Aux ducts is exactly where I ended up in my testing as well and that was easy to hand grind ,test , then digitise to
    have 5 axis CNC machined.
    Filling the floor with weld is a nightmare once the cylinder has been run ,and then the cost of a replate means I simply havnt had
    a chance to experement yet.
    But going higher sure looks like it is the go , as the wider Aux ducts need compensating for in the extra area change past the septum ends.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  7. #31717
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    27th October 2013 - 08:53
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    hey guys I was looking and I could easily make a simple four sided duct for the front of the rad with 1.5mm thick aluminum plate. each side would only be able to extend about 3" in front of the rad and theres a lot of tubing obstructions for the incoming air to deal with but I don't really see any downside to doing this. what do you guys think ? I found a article that says theres no need for the duct to expand any more than 7* as it goes from entrance to the rad cores. does this sound about right ? this isn't a road going bike but I figured some simple front ducting would be easy enough to make and it should do a bit better at directing some air to the cores, rather than leaving the rad with nothing at all. https://www.linkedin.com/pulse/air-d...ns-willem-toet

    one last question about the 7*. are they meaning each wall would expand 7* ? so basically the opening of the duct would be smaller than the rad cores because each wall is leaning in 7*
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  8. #31718
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    18th May 2007 - 20:23
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    Quote Originally Posted by peewee View Post
    I figured some simple front ducting would be easy enough to make and it should do a bit better at directing some air to the cores, rather than leaving the rad with nothing at all. https://www.linkedin.com/pulse/air-d...ns-willem-toet .... basically the opening of the duct would be smaller than the rad cores because each wall is leaning in 7*
    That is a rely interesting article.

    I have posted some of it below.

    Radiator cooling entries. With a fixed point of blockage (such as a radiator) you can increase the rate of expansion beyond the normal 7 degree limit as you approach the core (aerodynamic blockage) itself. It is a trick many aero people use in all sorts of applications. So use increasing expansion as you get close to the core of the radiator. It is a good strategy to do that in any case if you can. A radiator entry should be at least 20% of the area of the core for most motorsport applications. Of course this is influenced by the speed of the vehicle, the radiator area, heat rejection etc. but that’s a good starting point. If you go significantly bigger you typically pay the price of some drag.

    Some more from the same author:-
    https://www.linkedin.com/today/posts/willemtoet1


  9. #31719
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    20th January 2010 - 14:41
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    Quote Originally Posted by TZ350 View Post
    That is a rely interesting article.

    I have posted some of it below.

    Radiator cooling entries. With a fixed point of blockage (such as a radiator) you can increase the rate of expansion beyond the normal 7 degree limit as you approach the core (aerodynamic blockage) itself. It is a trick many aero people use in all sorts of applications. So use increasing expansion as you get close to the core of the radiator. It is a good strategy to do that in any case if you can. A radiator entry should be at least 20% of the area of the core for most motorsport applications. Of course this is influenced by the speed of the vehicle, the radiator area, heat rejection etc. but that’s a good starting point. If you go significantly bigger you typically pay the price of some drag.
    The drag applies to physical size of the radiator as well.
    Remember the louvers shutters on planes they controlled the openings so as they flew faster they made the openings smaller to cut down on drag. they had 6 positions on a Spitfire.
    Also looks like it shut down the outlet and changed the angle of attack as well.
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    Mustang was a bit different it was suposed to add thrust, i belive the Britten set up was very similar
    https://en.wikipedia.org/wiki/Meredith_effect
    https://www.quora.com/Would-the-P-38...nar-flow-wings
    http://silencetwisterbuild.blogspot....or-theory.html
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    Peter Williams used to change the entry arrea on the JPS Norton with Daytona being the smallest.




    Thoughtful Engineering Is A Powerful Source Of Conversation

    By Kevin Cameron April 11, 2019
    In 1973, Peter Williams brought to Daytona his evolving concept of what could be achieved in racing with the limited power of Norton’s pushrod parallel-twin 750. In conversation, what came through was his cheerful and strong belief that thoughtful engineering, as opposed to reliance upon tradition, could still improve the motorcycle significantly.

    As an example, cooling air for his engine’s head and cylinders was controlled by choice of an orifice plate, installed in the wind-tunnel-developed fairing just ahead of the engine. On a high-speed track such as Daytona, the smallest orifice would be used, with larger ones for tracks on which average air velocity would be less. It is, he noted, more efficient to flow air around the motorcycle than to let it flow through it. This is why aircraft powered by piston engines had either radiator shutters for liquid-cooling or cowl flaps to adjust cooling airflow to the power being used. The old practice of leaving the whole front of the fairing open ahead of the engine turned the bike into a large drag-producing air scoop—more just a cover rather than streamlining. Peter admitted just the cooling air needed. With its sophisticated air management, Peter’s design was just as fast as our 750cc Kawasaki two-strokes.

    The area of the fairing behind Peter’s front wheel was a completely non-intuitive flat surface, the veritable “barn door” perpendicular to airflow. Why? British aircraft in World War II equipped with arrays of radar dipoles would have lost a lot of top speed had a partial solution not been found; later airborne radars had steerable dish antennas inside of streamlined fiberglass fairings. The dipole arrays were therefore placed ahead of flat surfaces. Air, slowing as it piled up in front of such surfaces, generated less drag as it passed through the dipoles. The aerodynamically “nasty” exposed fork and front wheel of a racing motorcycle, looking just like a radar dipole array to oncoming airflow, was therefore treated in the same way. The flat surface behind the front wheel pushed a lump of low-velocity air ahead of itself, within which the wheel generated significantly less drag.
    https://www.cycleworld.com/thoughtfu...e-conversation

  10. #31720
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    27th October 2013 - 08:53
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    heres a few photo someone might find useful
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  11. #31721
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    19th June 2011 - 00:29
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    Quote Originally Posted by peewee View Post
    this ktm rad turned out to be the perfect size for what i needed (yes im going to use rubber isolater bushings). brackets are on and old nipples are cut off and plugged. just have to put a couple new nipples on
    seems very small in size for a high power twin cylinder ?

  12. #31722
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    Quote Originally Posted by JanBros View Post
    seems very small in size for a high power twin cylinder ?
    for drag racing i think it will be a good size

  13. #31723
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    14th January 2019 - 16:00
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    Quote Originally Posted by wobbly View Post
    I must say that the so call " Wobbly " exhaust duct parameters are based on square bore/stroke high output engines and thus oversquare
    dimensions will give excessive lengths.
    Lifting the duct floor is only possible once the blowdown has been fully optimised with Aux ports right around to bore center and pin plugs fitted.
    Even then I believe Jan only dyno tested up 3mm in a 54,5 stroke and that is as far as I have dared go.
    The floor should exit perpindicular then form a ski jump slope downward, and flattening asap.
    The roof should exit at 25* then form a radius , reducing in slope.
    This shape tends to equalise the cross sectional area at the point where the side ducts enter the main.
    I have started to think that maybe even attempting a convex roof and or duct floor shape is needed to reduce the area/colume even further.
    Recently I have been testing much larger ( wider ) swooping Aux ducts , and this increases peak and overev power up to a point of diminishing returns
    and then the midrange suffers.
    But of course widening the side ducts increases the area just past the Aux septum ends and on down further to the exit point , making
    this bigger than the 75% rule.
    So further changes to reduce the duct volume need looking at now.
    Thanks, Wobbly. I don't believe anyone in the snowmobile world has taken the auxiliaries out as far as Jan and you have. So the best way forward in your opinion would be to develop the auxiliary exhaust before anything else or would at the least filling the exhaust duct floor and roof from round to the actual port shape with auxiliary tunnels with no reduction in duct area be worthwhile?

  14. #31724
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    18th May 2007 - 20:23
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    .
    Click image for larger version. 

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    I have been making some progress fitting the CVT reduction box and positioning the crankcase on the CVT NX4 project. A few alignment issues but it is all looking possible.

    The front tire hitting the pipe under braking/cornering has often been a problem on other builds but this is the first time I have had to be aware of the tire possibly hitting the head......

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    The crankcases halves are going to be mounted either side of the 12mm plate like I did in the original GP-NSR110.

    The original GP-NSR110 was deliberately made with stupid amounts of crankcase volume and it worked well.

    Click image for larger version. 

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    And with a long RD400 rod and the original scooter crankshaft there is going to be insane amounts of crankcase volume in the new CVT engine. It will be interesting to see how that goes. Being rotary valve I might get away with it, in fact it may even show a performance benefit. If its a dud then I will convert it to 70cc (class rules) and turbocharge it and have lots of high crankcase pressurized mixture.


  15. #31725
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    Quote Originally Posted by JanBros View Post
    seems very small in size for a high power twin cylinder ?
    heres how i look at it and maybe im wrong. ive seen people use bigger ones. also ive seen them use just a small aluminum water box. i guess it depends on packaging limitations, cost of a radiator vs small water box, how many passes you want to make before shutting down the engine to cool, etc etc. also theres small 4" spal fans, mini electric water pumps. so theres alot of different methods to choose. i want to first see how the engine reacts with radiator of 4.5" x 11" in size , simple ducting and crankshaft driven waterpump. maybe later i can add better cooling methods if needed. also i use methanol which is a bit different than petrol, as your aware im sure

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