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Thread: ESE's works engine tuner

  1. #30211
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    28th August 2015 - 00:01
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    Quote Originally Posted by Haufen View Post
    Don't do it. The BP is the least useful port of all. Focus on B instead if you can choose. I once blocked the BP out of curiosity, and other than half a horse or so (which could be related quite well to the then reduced transfer TA) nothing happened.
    Thanks, that's starting to be my thought as well. Should the B port be angled up around 5 degrees like the traditional design or should it be changed to scavenged the rear wall of the cylinder better? Should the B port hook be the same as with a boost port or should the flow collide straight across with the opposite B port? A successful piston port design I've raced has the B port with a flat top and no hook. Something like the images below.

    Lohring Miller

    Click image for larger version. 

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    Last edited by lohring; 22nd July 2018 at 07:41. Reason: add images

  2. #30212
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    18th March 2012 - 08:35
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    Quote Originally Posted by TZ350 View Post
    Sorry to hear about the disaster......

    When we have disasters we say to ourselves, at least we know the formula because the formula is often more valuable than the damage discovering it.
    Now i have taken it apart and measured it.
    I cannot actually measure any damage so it΄s worn under 0.005mm as max.
    So i think it is possible to save it, i will have a engineshop diamondhone it and put a new ring into it, piston is ok.

    Some kind of luck in all the bad luck

  3. #30213
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    8th February 2007 - 20:42
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    If an engine looses only a tiny amount of power if the scavenging regime is changed by blocking the B.P than all that means is the A & B scavenging system was very wrong to start with.
    Running a modern setup with near flat ,huge B ports with a rear wall hook, along with smaller A ports that effectively axially jump over the B port columns, there is no way that
    flow regime can create a correct " leaning tower " up the back wall with no B.P directional control included.
    By definition a 4 port must have greater axial up angles and no way could you use a front B port wall that is radially perpendicular - like Jan developed at Aprilia.
    What we regard as normal axial and radial angles nowdays in a 5 port were slowly and meticulously changed over time to give the highest scavenging efficiency along with a high
    trapping ratio - simply deleting the B.P in this setup ( and thereby assuming it does nothing due to no power loss ) would be saying in effect that all that development was a complete waste of time
    and a huge effort should have been directed at 4 ports all along - dont think so.
    If a B.P makes so little difference to a good 5 port scavenging system, why does it make a huge impact when you cut a radius on the piston timing edge.
    I havnt done the test of leaving the edge in front of the B.P uncut , but reports are that it works very well.
    All I do know so far from tests is that a radius big enough to make the B.P flow attach to the piston ( and thus less to the rear wall ) kills power badly.
    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.

  4. #30214
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    22nd November 2013 - 16:32
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    ETec Direct injection.
    OMC (Johnson & Evinrude) first released the Ficht DI system in 1996. This turned out to be a techo disaster with OMC filing for bankrupcy in 2000. Taken over in 2001 by Bombardier, the Evinrude was released in 2004 with a refined & properly developed Ficht system called Etec.
    So, 22 years later, I reckon it’d be reasonably safe to have a play without having lawsuits or just suits arriving with the 2nd Amendment behind them. I think patent life in the US if 20 years and Oz it is 17.

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    "Success is the ability to go from one failure to another with no loss of enthusiasm.”

  5. #30215
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    3rd January 2012 - 01:25
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    Quote Originally Posted by wobbly View Post
    If an engine looses only a tiny amount of power if the scavenging regime is changed by blocking the B.P than all that means is the A & B scavenging system was very wrong to start with.
    Running a modern setup with near flat ,huge B ports with a rear wall hook, along with smaller A ports that effectively axially jump over the B port columns, there is no way that
    flow regime can create a correct " leaning tower " up the back wall with no B.P directional control included.
    By definition a 4 port must have greater axial up angles and no way could you use a front B port wall that is radially perpendicular - like Jan developed at Aprilia.
    What we regard as normal axial and radial angles nowdays in a 5 port were slowly and meticulously changed over time to give the highest scavenging efficiency along with a high
    trapping ratio - simply deleting the B.P in this setup ( and thereby assuming it does nothing due to no power loss ) would be saying in effect that all that development was a complete waste of time
    and a huge effort should have been directed at 4 ports all along - dont think so.
    If a B.P makes so little difference to a good 5 port scavenging system, why does it make a huge impact when you cut a radius on the piston timing edge.
    I havnt done the test of leaving the edge in front of the B.P uncut , but reports are that it works very well.
    All I do know so far from tests is that a radius big enough to make the B.P flow attach to the piston ( and thus less to the rear wall ) kills power badly.
    You are right, that cylinder of mine was not really state of the art. And neither is lohring's from what I can see at his pictures. I'd still give it a try.

    The loop scavenged engines with the best trapping efficiency (by far) are 4 port and used in gardening and forresting. These can reach up to 96% without an expansion chamber pushing the charge back. If they wanted to have a BP, they could. But they don't.

    I assume that the radiused edge on the BP area increases scavenging losses by directing part of the BP charge directly out of the exhaust port as it attached to the crown. This would be very likely not to come back by the exhaust port as it is lost very early in the cycle. Were there any clues (max EGT for peak power difference?, jetting etc? - anything that indirectly hints to trapping efficiency) this might have happened? So to answer your question on "why does it make a huge impact when you cut a radius on the piston timing edge": because it allows for more scavenging losses as you allow charge to shoot throug the basement of the tower. If you just close the BP, that is a different mechanism: the tower may lean a bit more away from the exhaust port - which has the potential for very high trapping efficiency (see chansaws, blowers, trimmers etc.).

    As the development direction has made the BP smaller and smaller over the years. Why not max this out by trying something a bit brave? Compared to the other ports, the BP offers far less TA vs. the bore area it uses. If you could block the BP on the TM with a gasket, and rejet if necessary, to get a first impression on a modern 2T, that'd be really cool. To verify or falsify my hypothesis on the working mechanism, you could then also try a blocked BP in combination with the radiused piston if the results turn out well with the blocked BP and normal piston. What do you think?

  6. #30216
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    18th May 2016 - 19:19
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    Quote Originally Posted by wobbly View Post
    Hi Jan, I have been flat out building test pipes for TM, as well as doing the record breaking 350cc Pre 81 Land Speed Project at Bonneville.
    Thus I have not been able to remove the test cylinder from the dyno to get it coated.
    Franco is way too secretive to tell me I think, if his non cooled duct was a failure or not.
    But i will ask, as soon I have a result to show him - wont be long.
    I had originally been obsessed with getting over 50 Hp along with plenty of overev power, but the 30mm carb seems to prevent any real
    extra peak power.One pipe made 49.6 and had 6 more at 14500, but on track that was barely faster.
    So I have been hard at work trying to get more front side power, ie going up to the peak.
    Here is where I am at now, and building/dynoing this pipe today.
    hi wobbly I just bought engmod 2t I would like to have some info if possible of course, about a simulation of the engine tm kz10b stock,a reference value in hp you find how much engine stock simulate?default values to enter combustion,temperature,thank you

  7. #30217
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    8th February 2007 - 20:42
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    I dont have a B model TM on this computer, it was stolen from my workshop several years ago.
    But here is a C model pack.The modelling is all but identical apart from the pipe - easy to change.
    It uses the step updated function correctly for the header and the stinger.

    Blocking the C port isnt on the radar, as it would be illegal to change the number of ports in the cylinder.
    I may get away with a gasket blocking it though.
    But I dont understand how a 4 port creates a " better " trapping efficiency, as I said before to create a good scavenging loop the radial and axial angles
    must be steeper ( as you dont have a boost port attaching the flow to the rear wall).
    Thus with the steeper axial angles , the loop length is shorter, giving more short circuiting opportunity in the time frame from EPO to EPC.
    And again with no rear wall flow attachment , the loop would tend to angle more toward the Ex port, unless the radial angles are very steep, creating again a shorter loop time.
    My belief would be that the scavenging efficiency would be far more compromised, so even with a really good trapping efficiency, less power would be the result - due to the trapped charge being Ex gas diluted..
    Yes you are right the bigger radius on the piston had lower EGT,and with a 2 jet change it came back, but the power didnt.
    Repeatably CNC cutting a radius on the piston, with a gap left stock, needs a radius form tool in a 5 axis , way too much time, money and effort at this stage - especially with the huge gains
    I found by simply doing the Ex duct correctly.

    Bugger I cant post a .pack file , can this be changed or do I have to keep .zip it.
    Attached Files Attached Files
    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.

  8. #30218
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    28th August 2015 - 00:01
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    I just got a much better idea on another forum. If I run a divided intake port I can feed the boost port with a hole in the piston. See below.

    Lohring Miller

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  9. #30219
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    12th March 2010 - 16:56
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    just as an aside I guess but I did once change my DT360 so as to have no boost port as such. The port was changed so as to point forward straight towards the exhaust port, flat delivery and timed slightly less than the other ports. The idea being that the A ports flow would catch this C port flow and send it up the back of the cylinder with everything else.
    Did it go any better? Seat of the pants dyno so who knows ulitamtely but it feel like it had more power and wider power spread, certainly didn't have any less.

  10. #30220
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    18th May 2016 - 19:19
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    Thumbs up

    Quote Originally Posted by wobbly View Post
    I dont have a B model TM on this computer, it was stolen from my workshop several years ago.
    But here is a C model pack.The modelling is all but identical apart from the pipe - easy to change.
    It uses the step updated function correctly for the header and the stinger.

    Blocking the C port isnt on the radar, as it would be illegal to change the number of ports in the cylinder.
    I may get away with a gasket blocking it though.
    But I dont understand how a 4 port creates a " better " trapping efficiency, as I said before to create a good scavenging loop the radial and axial angles
    must be steeper ( as you dont have a boost port attaching the flow to the rear wall).
    Thus with the steeper axial angles , the loop length is shorter, giving more short circuiting opportunity in the time frame from EPO to EPC.
    And again with no rear wall flow attachment , the loop would tend to angle more toward the Ex port, unless the radial angles are very steep, creating again a shorter loop time.
    My belief would be that the scavenging efficiency would be far more compromised, so even with a really good trapping efficiency, less power would be the result - due to the trapped charge being Ex gas diluted..
    Yes you are right the bigger radius on the piston had lower EGT,and with a 2 jet change it came back, but the power didnt.
    Repeatably CNC cutting a radius on the piston, with a gap left stock, needs a radius form tool in a 5 axis , way too much time, money and effort at this stage - especially with the huge gains
    I found by simply doing the Ex duct correctly.

    Bugger I cant post a .pack file , can this be changed or do I have to keep .zip it.
    Hi wobbly thanks a lot for the file, with you I saved time ,however I would like to know how you have done to measure all the ignition data?you are on new engine project at this time?TM new approval?in any case a big thank you for your help and all your posts every time very interesting

  11. #30221
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    Quote Originally Posted by wobbly View Post
    Blocking the C port isnt on the radar, as it would be illegal to change the number of ports in the cylinder.
    I may get away with a gasket blocking it though.
    But I dont understand how a 4 port creates a " better " trapping efficiency, as I said before to create a good scavenging loop the radial and axial angles
    must be steeper ( as you dont have a boost port attaching the flow to the rear wall).
    Thus with the steeper axial angles , the loop length is shorter, giving more short circuiting opportunity in the time frame from EPO to EPC.
    And again with no rear wall flow attachment , the loop would tend to angle more toward the Ex port, unless the radial angles are very steep, creating again a shorter loop time.
    My belief would be that the scavenging efficiency would be far more compromised, so even with a really good trapping efficiency, less power would be the result - due to the trapped charge being Ex gas diluted..
    Yes you are right the bigger radius on the piston had lower EGT,and with a 2 jet change it came back, but the power didnt.
    Repeatably CNC cutting a radius on the piston, with a gap left stock, needs a radius form tool in a 5 axis , way too much time, money and effort at this stage - especially with the huge gains
    I found by simply doing the Ex duct correctly.
    It would be really good to have a calibrated CFD model now. Do TM happen to have one? When I was working on low emission two-stroke engines (I am sure you'd excel at it, as it is just like tuning for power, just the other way round: keep the power the same and improve trapping efficiency), I had access to all the results from the CFD supercluster computer in Italy and spent part of my time at work to "watch" scavenging videos of different engines at various configurations and engine speeds, analysing the scavenging pattern, cutting the model into sections, playing back and forth etc., until I was sure I had learnt everything there was to learn from. You could even see the small wave from the back wall of the box exhaust returning at the exhaust port. From what I learned I'd say that steeper axial angles might not even be necessary as the bulk flow starts at around BDC and the upward moving piston then supports the scavenging regime on the way up.

    I found the side view of a 4 port scavenging on youtube - if you stop the video at 4s, you can see the column leaning to the left before starting the loop. If there were a BP, then the column would be more straight and hence closer to the exhaust port. Depending on the engine speed and loop speed (and pipe geometry), this may or may not be beneficial, but even if you had the same amount of charge inside the cylinder after EPC, the charge which had not taken the trip into the exhaust port and back (no matter how well it is cooled), will likely be cooler.

    And because of this, and because decades of scavenging developments point to making the BP smaller and smaller, and because it can be done rather quickly by just blocking it with a gasket, I think this is worth giving a try. Of course it won't be perfect at first try, but it might already show some potential (e.g. by losing less power than what might be expected from the TA difference).

    4 port scavenging on youtube
    https://www.youtube.com/watch?v=3F_0PvbKo44

    exhaust port view for completeness:
    https://www.youtube.com/watch?v=M53nersJJ3o

  12. #30222
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    Generating the combustion file is easy to do - the ignition timing is fixed, as is the A/F ratio.
    Run your model as completed in Turbulent Model mode - very slow as the crunching is huge.
    Then in Post, open that last file to choose what parameters you want to see, you will then see on the right hand side a radio button
    for " Write Combustion File ".Activate that, and save it with a new name ( I always call it Turb ).
    Make sure it ends up in 2Stroke folder, not in the project one.
    Then you can choose that new Combustion file when opening the project.
    This then uses all the data generated by the Turbulent run, but now you can run Prescribed every time - way way faster.

    I was given the job of developing the next TM homologation pipe in secret , away from Italy , as it costs them a fortune to have 1 offs made , and nothing is secret if enough money changes hands.
    That job I completed with a really big gain, on the dyno , and Franco/DeConto track tested it as well.
    Elto have made test pipes from my CAD patterns , but no one has seen the actual straight line drawing - and no one will untill the homologation papers are signed off.
    Slowly I have gained enough credibility with them to get more detailed work, but there are very big ego's involved of course as they are the current World Title holders ( so dont need me involved ).
    But I keep making more power than they do , so I just keep on doing it to annoy them.

    Haufen, no TM dont have a CFD setup, they should as they use NX as a CAD platform.I have their full solid model of the C cylinder so I could use it in the SolidWorks
    CFD package, but hell I find it hard to keep up with work as it is , without trying to learn a new platform as well.
    But for sure I will try a blanking gasket and see the changes in the dyno data , and go from there.
    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.

  13. #30223
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    16th February 2017 - 14:26
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    I'm almost done porting my 2.1mm overbore YZ250 cylinder, the port windows are where I want them, using a laser cut port template, Main exh: 190, Aux exh: 185, A:122, B:121 and C:119.
    Exhaust is widened to the full width of the powervalve blade. The A ports are about 2mm wider toward the exhaust port to get the required transfer TA. I smoothed the Boyesen passages and kept the septums rounded.
    Tidied up casting flash everywhere but left the intake and transfers with a rough finish.
    Main and aux exhaust ducts cleaned up and blended, not quite polished but smooth.

    I've left the radial transfer angles as standard.
    I measured the standard axial angles as A:16 and B:14. After porting I have angles of A:22 and B:15. Frits' calculation gives values of A:26 and B:12

    Looking for some advice on where to go from here, should I:
    • Flatten out the A ports to 16 degrees to return to standard configuration,
    • Flatten out the B ports to 12 to closer align with Frits' values, or;
    • Leave them how they are right now, as some sort of compromise?

    What would be the effects of the above options?
    My goal is to move the power curve up about 800rpm, powerband width is important since it's a street motor with a 5 speed box.

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  14. #30224
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    I would lift the A port to increase the angle and the duration.
    More stagger = wider bandwidth.
    If you want more Blow STA to match, then the Aux port roofs can go alot closer to the main.
    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.

  15. #30225
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    20th January 2010 - 14:41
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    Quote Originally Posted by wobbly View Post
    I would lift the A port to increase the angle and the duration.
    More stagger = wider bandwidth.
    If you want more Blow STA to match, then the Aux port roofs can go alot closer to the main.
    I have been meaning to ask you wob just how big were the reeds on the BSL I looked at a pic the other day and they seemed to fill the whole gap between the bore centers?
    I was looking at a pic of the NSR500 the other day and even that was compromised In the effective width as they were still offset which I never expected with there wide centers dud to the single crank.
    I am picking they were much larger than the RS125s other wise there should have been more room.
    The BSL on the other hand looks symmetrical.
    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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