Page 2313 of 2625 FirstFirst ... 1313181322132263230323112312231323142315232323632413 ... LastLast
Results 34,681 to 34,695 of 39365

Thread: ESE's works engine tuner

  1. #34681
    Join Date
    8th February 2007 - 20:42
    Bike
    TZ400
    Location
    tAURANGA
    Posts
    3,885
    Again I am amazed at the technology ( or lack of it ) in these small RC engines.
    Its been shown by tests done years ago that a downward angle of 25* of the Exhaust duct roof gives the best compromise of blowdown flow and duct velocity.
    But in the previous post we have a duct pointing upward , surely that alone invalidates any comparison with any other layout considerations.
    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. #34682
    Join Date
    2nd July 2011 - 08:25
    Bike
    2006, KTM, 250 SX
    Location
    Sweden
    Posts
    282
    Quote Originally Posted by lohring View Post
    The side and rear exhaust engines we tested had either liners or standard closed transfers. Quickdraw once made crankcases for both types that differed only in the bolt pattern and cutout areas for the transfers. I have one of each type that are going into the proposed opposed piston engine. The ringless piston engines used in smaller models don't seem to have the same issues, but I'm not aware of anyone who has done careful test comparisons. Boaters use a variety if bent headers to run all types of exhausts. Below is the most extreme, a 180 degree header. I've run one of these engines and it was definitely more powerful than the older rear exhaust version. However, the one piece design of the new version was stiffer along with a bigger intake and other factors.

    Lohring Miller

    Attachment 347803 Attachment 347804
    That recons, re. your tests of different cylinder directions.
    Those pictures are of ringless engines, right? If not, the 180degree one should be pretty darn similar to the rear exhaust with regards to potential ring/exhaust port issues.

    Quote Originally Posted by wobbly View Post
    Again I am amazed at the technology ( or lack of it ) in these small RC engines.
    Its been shown by tests done years ago that a downward angle of 25* of the Exhaust duct roof gives the best compromise of blowdown flow and duct velocity.
    But in the previous post we have a duct pointing upward , surely that alone invalidates any comparison with any other layout considerations.
    That duct for sure looks odd. Id guess its to avoid the huge flywheel, in that sense, for sure a side or front exhaust would be better.

    There are some quite clever RC engines though, the MB Profi for one.
    https://fiorimet.home.xs4all.nl/

  3. #34683
    Join Date
    20th April 2011 - 08:45
    Bike
    none
    Location
    Raalte, Netherlands
    Posts
    3,341
    Quote Originally Posted by teriks View Post
    There are some quite clever RC engines though, the MB Profi for one. https://fiorimet.home.xs4all.nl/
    MB is the brand that brought me into contact with model engines. In the mid 1990s physicist Rob Metmemeijer approached me with the problem that the power curve of his 6,5cc two-stroke engines couldn't handle the power absorption curve of his propellers. Either the engine would not rev past the torque dip at 2/3 of max. torque rpm, or the propeller had to be so light that the engine revved way beyond its maximum power rpm. Rob had heard some whispers about exhaust power valves and I happened to have the drawings of the Cagiva 500-4 cylinder (a carbon-copy of the Yamaha YZR500 cylinder) at my fingertips.
    Surprise: a few weeks later Rob showed me a running 6,5cc power valve engine. Now here was a guy that I would like to work with! However, I felt there had to be a more KISS-like solution for the torque dip problem, so after visiting a couple of F3D model pylon races to see what was needed, I came up with an exhaust pipe that is now universal in F3D.
    The pipe was followed by a hardchromed sleeveless cylinder (for an engine without piston rings, hardchrome is just as good as nikasil) with teacup-shaped transfer ducts and my idea of port timings and scavenging angles. The engine also got ceramic crankshaft bearings. The result is the current MB40 Profi engine. The '40' stands for the 0.40 cubic inch cylinder capacity and Profi is the Ukrainian firm that takes care of the serial production (everybody wants an MB40) while Rob Metkemeijer still builds the prototpyes.
    Click image for larger version. 

Name:	5-port-1.jpg 
Views:	246 
Size:	195.7 KB 
ID:	347805 Click image for larger version. 

Name:	FI20001.JPG 
Views:	375 
Size:	520.0 KB 
ID:	347808 Click image for larger version. 

Name:	FI200203 klein.jpg 
Views:	230 
Size:	74.5 KB 
ID:	347807 Click image for larger version. 

Name:	pijp19.JPG 
Views:	350 
Size:	118.2 KB 
ID:	347806

  4. #34684
    Join Date
    18th May 2007 - 20:23
    Bike
    RG50 and 76 Suzuki GP125 Buckets
    Location
    Auckland
    Posts
    10,473

  5. #34685
    Join Date
    28th August 2015 - 00:01
    Bike
    1975 Hodaka Wombat
    Location
    Eugene, Oregon, USA
    Posts
    302
    A long time ago a model speed engine builder told me that piston to liner fit followed by head button design were the most important factors for high performance. The first is due to the big effect of friction in these small engines. The second is because compression along with the glow plug wire diameter sets the ignition timing. All the things we worry about in larger engines are nice refinements. Our 26 cc gasoline engines definitely benefit from better transfers and ports. Frits' design definitely helped the 6.5 cc engine, but the cruder designs of the Nelson 40, now sold by Aero Racing Engines, and Jett engines are still competitive.

    Lohring Miller

  6. #34686
    Join Date
    28th August 2015 - 00:01
    Bike
    1975 Hodaka Wombat
    Location
    Eugene, Oregon, USA
    Posts
    302
    Quote Originally Posted by Frits Overmars View Post
    MB is the brand that brought me into contact with model engines. In the mid 1990s physicist Rob Metmemeijer approached me with the problem that the power curve of his 6,5cc two-stroke engines couldn't handle the power absorption curve of his propellers. Either the engine would not rev past the torque dip at 2/3 of max. torque rpm, or the propeller had to be so light that the engine revved way beyond its maximum power rpm. Rob had heard some whispers about exhaust power valves and I happened to have the drawings of the Cagiva 500-4 cylinder (a carbon-copy of the Yamaha YZR500 cylinder) at my fingertips.
    Surprise: a few weeks later Rob showed me a running 6,5cc power valve engine. Now here was a guy that I would like to work with! However, I felt there had to be a more KISS-like solution for the torque dip problem, so after visiting a couple of F3D model pylon races to see what was needed, I came up with an exhaust pipe that is now universal in F3D.
    The pipe was followed by a hardchromed sleeveless cylinder (for an engine without piston rings, hardchrome is just as good as nikasil) with teacup-shaped transfer ducts and my idea of port timings and scavenging angles. The engine also got ceramic crankshaft bearings. The result is the current MB40 Profi engine. The '40' stands for the 0.40 cubic inch cylinder capacity and Profi is the Ukrainian firm that takes care of the serial production (everybody wants an MB40) while Rob Metkemeijer still builds the prototpyes.
    Click image for larger version. 

Name:	5-port-1.jpg 
Views:	246 
Size:	195.7 KB 
ID:	347805 Click image for larger version. 

Name:	FI20001.JPG 
Views:	375 
Size:	520.0 KB 
ID:	347808 Click image for larger version. 

Name:	FI200203 klein.jpg 
Views:	230 
Size:	74.5 KB 
ID:	347807 Click image for larger version. 

Name:	pijp19.JPG 
Views:	350 
Size:	118.2 KB 
ID:	347806
    Are you sure I didn't braze that pipe? I'm about that neat with my brazed joints. I like the pipe below for real power.

    LOL

    Lohring Miller

    Click image for larger version. 

Name:	FATpipe.JPG 
Views:	406 
Size:	55.8 KB 
ID:	347810

  7. #34687
    Join Date
    2nd July 2011 - 08:25
    Bike
    2006, KTM, 250 SX
    Location
    Sweden
    Posts
    282
    Quote Originally Posted by Frits Overmars View Post
    MB is the brand that brought me into contact with model engines. In the mid 1990s physicist Rob Metmemeijer approached me with the problem that the power curve of his 6,5cc two-stroke engines couldn't handle the power absorption curve of his propellers. Either the engine would not rev past the torque dip at 2/3 of max. torque rpm, or the propeller had to be so light that the engine revved way beyond its maximum power rpm. Rob had heard some whispers about exhaust power valves and I happened to have the drawings of the Cagiva 500-4 cylinder (a carbon-copy of the Yamaha YZR500 cylinder) at my fingertips.
    Surprise: a few weeks later Rob showed me a running 6,5cc power valve engine. Now here was a guy that I would like to work with! However, I felt there had to be a more KISS-like solution for the torque dip problem, so after visiting a couple of F3D model pylon races to see what was needed, I came up with an exhaust pipe that is now universal in F3D.
    The pipe was followed by a hardchromed sleeveless cylinder (for an engine without piston rings, hardchrome is just as good as nikasil) with teacup-shaped transfer ducts and my idea of port timings and scavenging angles. The engine also got ceramic crankshaft bearings. The result is the current MB40 Profi engine. The '40' stands for the 0.40 cubic inch cylinder capacity and Profi is the Ukrainian firm that takes care of the serial production (everybody wants an MB40) while Rob Metkemeijer still builds the prototpyes.
    Rob is quite amazing, not only theoretically clever, but extremely efficient in the workshop!
    That pipe of yours in not very easy to improve upon, that's for sure.

    Quote Originally Posted by lohring View Post
    A long time ago a model speed engine builder told me that piston to liner fit followed by head button design were the most important factors for high performance. The first is due to the big effect of friction in these small engines. The second is because compression along with the glow plug wire diameter sets the ignition timing. All the things we worry about in larger engines are nice refinements. Our 26 cc gasoline engines definitely benefit from better transfers and ports. Frits' design definitely helped the 6.5 cc engine, but the cruder designs of the Nelson 40, now sold by Aero Racing Engines, and Jett engines are still competitive.
    Lohring Miller
    Actually neither Jett nor Nelson is competitive in F3d racing, since quite some time.
    While there are some other interesting F3d engines, the MB is the only one really commercially available.

  8. #34688
    Join Date
    20th April 2011 - 08:45
    Bike
    none
    Location
    Raalte, Netherlands
    Posts
    3,341
    Quote Originally Posted by lohring View Post
    I like the pipe below for real power.
    Click image for larger version. 

Name:	FATpipe.JPG 
Views:	406 
Size:	55.8 KB 
ID:	347810
    Shortly after the first appearance of my F3D pipe, competitors started to rumble about "the Fat Dutch Pipe", so we decided to give them something to rumble about: a picture of an F3D model plane with one of my 125cc dyno test pipes. Left yours truly, right Robbert van den Bosch, many times European F3D champion and some time after this photo was taken, also world champion.
    When we first met, I asked him what he did for a living. He answered: "Bus driver". It turned out he was a Boeing 737-captain. His reaction: "Same job, but it pays better".

    Quote Originally Posted by teriks View Post
    Rob is quite amazing, not only theoretically clever, but extremely efficient in the workshop!
    That pipe of yours in not very easy to improve upon, that's for sure.
    Actually neither Jett nor Nelson is competitive in F3d racing, since quite some time. While there are some other interesting F3d engines, the MB is the only one really commercially available.
    Rob (below) is an amazing person indeed. His daytime playing field is acoustics, for example giving the Royal Albert Hall a once-over, that kind of level. He got into building model engines because he and his late brother Bert took part (and became world champion) in teamracing, another branch of model flying.
    Teriks' remark, that the MB40 engine is the only commercially available F3D engine, requires some clarification. From Robs standpoint there is nothing commercial about it: he builds his engines purely to keep the sport going and there is no profit in it for him. Everybody can buy his engines, but active F3D competitors are given priority on the waiting list to keep their chances even.
    Click image for larger version. 

Name:	Rob Metkemeijer-2.jpg 
Views:	140 
Size:	60.2 KB 
ID:	347825

  9. #34689
    Join Date
    26th October 2020 - 19:17
    Bike
    Suzuki
    Location
    Chile,Santiago
    Posts
    3
    Great work Thomas! You are an intelligent person!:

  10. #34690
    Join Date
    19th June 2011 - 00:29
    Bike
    KR-1S, KR1-SV, KXR500, ZXR 4/600
    Location
    Belgium
    Posts
    269
    bought a KDX200 but sadly there are 2 cracks between the exhaust ports on the left. I'm in doubt as to whether have them welded and replated or have it sleeved. if welded, will they weld it through and through and not leave parts of the crack that can grow again? and if they weld it through, I'm in doubt as to if it will not harm the flow if the weld protrudes, hardly being able to correct that.
    I know the downsides off sleaving, but it 's just for having some off-road fun, not to ride it at max like a pro.

    also first time I've seen a raised exhaust port on a standard cylinder from the early '90ies
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	kdx.JPG 
Views:	187 
Size:	54.7 KB 
ID:	347837  

  11. #34691
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
    Posts
    20,500
    Blog Entries
    2
    Yeah they had a strange rotating power valve to open that and the rack and pinion arrangement used to seize and strip the gears.

    Change of needle was best improvement on mine.
    Don't you look at my accountant.
    He's the only one I've got.

  12. #34692
    Join Date
    8th February 2007 - 20:42
    Bike
    TZ400
    Location
    tAURANGA
    Posts
    3,885
    The plater here would vee the crack out , weld it up , bore and grind it back , and replate .
    Easy job.
    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. #34693
    Join Date
    19th June 2011 - 00:29
    Bike
    KR-1S, KR1-SV, KXR500, ZXR 4/600
    Location
    Belgium
    Posts
    269
    Quote Originally Posted by wobbly View Post
    The plater here would vee the crack out , weld it up , bore and grind it back , and replate .
    Easy job.
    no problem's welding through and through to avoid re-cracking ?

  14. #34694
    Join Date
    8th February 2007 - 20:42
    Bike
    TZ400
    Location
    tAURANGA
    Posts
    3,885
    A few cylinders are simply a bad design ( 4DP Yamaha TZ ) that crack no matter what , but the weld material is stronger than the cast alloy , so usually the weld is more reliable.
    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. #34695
    Join Date
    20th January 2010 - 14:41
    Bike
    husaberg
    Location
    The Wild Wild West
    Posts
    11,823
    Quote Originally Posted by JanBros View Post
    no problem's welding through and through to avoid re-cracking ?
    Closer to your home
    https://www.kiwibiker.co.nz/forums/s...post1130610635
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




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

Thread Information

Users Browsing this Thread

There are currently 85 users browsing this thread. (0 members and 85 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •