AccueilCalendrierGalerieFAQRechercherS'enregistrerConnexionNouveaux messages depuis dernière visite
Rechercher
 
 

Résultats par :
 
Rechercher Recherche avancée
Qui est en ligne ?
Il y a en tout 14 utilisateurs en ligne :: 2 Enregistrés, 0 Invisible et 12 Invités :: 2 Moteurs de recherche

coupekawa, polcat88

Le record du nombre d'utilisateurs en ligne est de 187 le Lun 3 Déc 2012 - 14:45
Derniers sujets
» [Technique] MotoGP : Ducati
Aujourd'hui à 1:26 par Marc

» [Oldies] Règlement GP 1949
Aujourd'hui à 1:21 par Marc

» [Oldies] Ils ont p'loté la belle à culbuter de Varese (2ème partie)
Hier à 18:50 par damienfollenfant

» [Oldies] Jack Findlay, pilote de légende
Hier à 18:24 par charly7728

» [Oldies] Renzo Pasolini, photos insolites
Hier à 18:08 par damienfollenfant

» [GP] MotoGP et télévision...
Hier à 17:23 par crigar

» [Oldies] C'était le bon temps...
Hier à 16:35 par Dakota

» [Oldies] "Martin Strattom" by ecrrmoto
Hier à 16:11 par ecrrmoto

» [Oldies] Documentation Motobécane
Hier à 15:47 par Mykeul

» [GP] Johann Zarco
Hier à 15:38 par Mykeul

» [MotoGP] KTM
Hier à 13:16 par freret alain robert

» [GP] Fabio Quartararo
Hier à 12:49 par Vivien57

» [Technique] La JBB-Metiss de A à Z...
Hier à 9:54 par BM1150R

» Christophe Guyot
Ven 18 Jan 2019 - 22:13 par Mykeul

» [Oldies] Malheureusement, ils sont partis...
Ven 18 Jan 2019 - 19:05 par ONLYAM

» [SORTIES] Charade Heroes - 22-23 Septembre 2018
Ven 18 Jan 2019 - 18:33 par spirit

» [WSBK] 2019
Ven 18 Jan 2019 - 17:48 par EDOUARD Jean

» Alain Genoud
Ven 18 Jan 2019 - 14:30 par bike70

» [Oldies] Angel Nieto Mike Hailwood ( Part 4 )
Ven 18 Jan 2019 - 13:38 par tripotemascagne

» [Oldies] Encore une BOUGIE !
Ven 18 Jan 2019 - 12:23 par justin

»  [Oldies] Les découvertes de Tonton Hubert (Part 4)
Jeu 17 Jan 2019 - 23:02 par philippe7

» [Oldies] Side-Car: quelques images
Jeu 17 Jan 2019 - 18:51 par enndewell joel

» [Oldies] Les photos d'Eilo Taka-prami
Jeu 17 Jan 2019 - 18:44 par philwood

» [MotoGP] Michelin
Jeu 17 Jan 2019 - 14:32 par Mykeul

» Grégory LEBLANC ....
Jeu 17 Jan 2019 - 12:13 par PLP

» MONDIAL Scugnizzo 75cc.
Mer 16 Jan 2019 - 17:39 par perruche

» [Oldies] Honda 750 Daytona
Mer 16 Jan 2019 - 11:59 par Tonton Hub

» [SORTIE] Amicale - des anciens – coureurs - motocycliste
Mer 16 Jan 2019 - 11:16 par enndewell joel

» [Sorties] Calendrier 2019 des manifestations, roulages, circuits, côtes,....
Mer 16 Jan 2019 - 11:15 par spyderman 32

» [Oldies] Quizz??????
Mer 16 Jan 2019 - 9:40 par MacPepR

La réclame...
Mots-clés
motobecane ducati side icgp 1000 classic metiss yamaha rouge aermacchi RACING 2018 moto fourche ROAD 2013 zone geco coupe 1973 france wanted triumph suzuki aprilia eurosport
Meilleurs posteurs
Marc
 
philwood
 
mickey
 
Pierre"PhilRead"
 
EDOUARD Jean
 
Jarno
 
Fügner
 
yves kerlo
 
janpol84
 
Dialmax
 
La réclame...

Partagez | 
 

 [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)

Aller en bas 
Aller à la page : Précédent  1 ... 20 ... 36, 37, 38, 39, 40  Suivant
AuteurMessage
Howard Gifford



Nombre de messages : 136
Age : 62
Localisation : Ottawa Canada
Date d'inscription : 01/05/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mar 26 Juin 2012 - 15:02

Was there a point in the development where more air flow resulted in no more gains in power or is airflow through the engine a function of power output. My theory is that if the pipe is not doing its job properly pushing the mixture back into the motorfrom that increased airflow will besimply lost out the tailpipe. With increased port area increasing airflow does the baffle cone angle need to be increased tohelp push this extra flow back into the motor? |You earlier stated you tried over 200 exhaust designs. Can you post the dimensions of the pipe you found worked best? As a pipe designer and builder I am curious about finding more power with the pipe.

And by the way I would be first in line with my money to buy your book. Two strokes oil runs through the veins of more people than you think. I have every two stroke book an article ever written. Most are full of \BS or gobbledygook but your knowledge is golden and should be recorded in some form.
Revenir en haut Aller en bas
Frits Overmars

avatar

Nombre de messages : 2131
Age : 70
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mar 26 Juin 2012 - 17:24

Howard Gifford a écrit:
Was there a point in the development where more air flow resulted in no more gains in power or is airflow through the engine a function of power output. My theory is that if the pipe is not doing its job properly pushing the mixture back into the motorfrom that increased airflow will besimply lost out the tailpipe.
Even if increased airflow increases the scavenging losses, it will also help in purifying the cylinder contents.
And even fresh mixture that directly short-circuits from the transfer ports into the exhaust ports, helps in cooling the piston.
Citation :
With increased port area increasing airflow does the baffle cone angle need to be increased to help push this extra flow back into the motor?
No, the baffle cone angle is already optimal; you cannot increase it at will. If you make it too steep, the returning pulse will turn into a shock wave that is very uneffective in pushing anything back into the cylinder.
Citation :
You earlier stated you tried over 200 exhaust designs. Can you post the dimensions of the pipe you found worked best? As a pipe designer and builder I am curious about finding more power with the pipe.
Jan, what do you think of this request?
Revenir en haut Aller en bas
wax



Nombre de messages : 60
Localisation : australia
Date d'inscription : 01/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 2:19

I have seen some engines using copper combustion chambers to help reduce detonation. Whats your thoughts on this, did you try it on the rsa and if so what was the results
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 3:55

Yes, a bridged exhaust was tried.
Of course!
2HP less.
Power is mainly determined by blowdown, which is better with a triple port.
A bridged exhaust is wider at the bottom.
Which means the transfers have to be smaller.
This gives less power.
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 7:32

Howard Gifford a écrit:
Was there a point in the development where more air flow resulted in no more gains in power or is airflow through the engine a function of power output. My theory is that if the pipe is not doing its job properly pushing the mixture back into the motorfrom that increased airflow will besimply lost out the tailpipe. With increased port area increasing airflow does the baffle cone angle need to be increased tohelp push this extra flow back into the motor? |You earlier stated you tried over 200 exhaust designs. Can you post the dimensions of the pipe you found worked best? As a pipe designer and builder I am curious about finding more power with the pipe.

And by the way I would be first in line with my money to buy your book. Two strokes oil runs through the veins of more people than you think. I have every two stroke book an article ever written. Most are full of \BS or gobbledygook but your knowledge is golden and should be recorded in some form.

I thought of doing it before I retired to Thailand.
No one wanted to edit it, so nothing came of it.
Then I gave away my tuning books, papers and notes.
So now there is no way I can do it anymore.
I have no photo's, designs or graph's, nothing.
Revenir en haut Aller en bas
wax



Nombre de messages : 60
Localisation : australia
Date d'inscription : 01/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 7:35

Jan Thiel a écrit:
Yes, a bridged exhaust was tried.
Of course!
2HP less.
Power is mainly determined by blowdown, which is better with a triple port.
A bridged exhaust is wider at the bottom.
Which means the transfers have to be smaller.
This gives less power.

Ok That makes sense.
I didnt think about it from that point of view, the exhaust port width at the bottom
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 7:38

In the end we reduced the width of the bottom of the exhaust port, and also raised the bottom.
That was a little bit better.
Then I stopped working.
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 7:40

Frits,

If you wish you can publish the exhausts sizes at this forum,no problem!
Revenir en haut Aller en bas
wax



Nombre de messages : 60
Localisation : australia
Date d'inscription : 01/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 7:41

Jan Thiel a écrit:
In the end we reduced the width of the bottom of the exhaust port, and also raised the bottom.
That was a little bit better.
Then I stopped working.
Im guessing that most of the work has been done by the time the piston gets to the bottom, By raising the bottom of the exhaust you would have had the exhaust port slightly higher than the piston at bdc ??
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 8:44

wax a écrit:
Jan Thiel a écrit:
In the end we reduced the width of the bottom of the exhaust port, and also raised the bottom.
That was a little bit better.
Then I stopped working.
Im guessing that most of the work has been done by the time the piston gets to the bottom, By raising the bottom of the exhaust you would have had the exhaust port slightly higher than the piston at bdc ??

Really most of the work must have been done when the transfers open!

We raised the bottom of the exhaust to about 2mm above the piston in BDC.

Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 8:50

Once a copper/bronze head insert was tried.
It made no difference to detonation.
Full throttle-detonation ended when we made the transfers as wide as possible.
Thus improving piston cooling.
The problem of part-throttle detonation remained.
Part-throttle causes pre-ignition due to the remaining burned gases.
Revenir en haut Aller en bas
GtG001



Nombre de messages : 81
Age : 64
Localisation : Adelaide, Australia
Date d'inscription : 03/06/2012

MessageSujet: Aprilia RSA 125   Mer 27 Juin 2012 - 9:00

Really most of the work must have been done when the transfers open!

We raised the bottom of the exhaust to about 2mm above the piston in BDC.

[/quote]

Hi Jan,
Did you do any more tests to see how far you could raise the exhaust port floor?
Had you thought about creating a transfer port under the exhaust port by raising the centre of the exhaust port floor?
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 9:09

Yes, I did that in 1974, without succes!

At Aprilia I had a cylinder cast, in 2007, with the underside of the exhaust raised to the level of the upper
transfer port height.
It was my intention to lower this until the power became good.
But when I realized that I would be retired when the cylinder would be plated I abandoned it, and had it
CNC machined to 'normal'
A pity!
Revenir en haut Aller en bas
wax



Nombre de messages : 60
Localisation : australia
Date d'inscription : 01/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 9:13

Jan Thiel a écrit:
Yes, I did that in 1974, without succes!

At Aprilia I had a cylinder cast, in 2007, with the underside of the exhaust raised to the level of the upper
transfer port height.
It was my intention to lower this until the power became good.
But when I realized that I would be retired when the cylinder would be plated I abandoned it, and had it
CNC machined to 'normal'
A pity!
How dare they.
Revenir en haut Aller en bas
GtG001



Nombre de messages : 81
Age : 64
Localisation : Adelaide, Australia
Date d'inscription : 03/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 9:23

Jan Thiel a écrit:
Yes, I did that in 1974, without succes!

At Aprilia I had a cylinder cast, in 2007, with the underside of the exhaust raised to the level of the upper
transfer port height.
It was my intention to lower this until the power became good.
But when I realized that I would be retired when the cylinder would be plated I abandoned it, and had it
CNC machined to 'normal'
A pity!

Jan, in adding the transfer under the exhaust port, were you looking at adding to the main column of fresh charge or allowing the suction of the exhaust to take it out the exhaust port to be pushed back later?
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 9:28

I was looking to add to the main transfer flow.
But the engine gave no power at all and did not rev.
I think the flow of this extra transfer port made a 180° turn, straight into the exhaust!
Maybe this cooled the exhaust gases so that the pipe could not work properly!
Probably the blowdown was not finished when it opened.
It was a little bit lower than the main transfers, and its direction was towards the opposite cylinder wall.


Dernière édition par Jan Thiel le Mer 27 Juin 2012 - 10:16, édité 1 fois
Revenir en haut Aller en bas
wax



Nombre de messages : 60
Localisation : australia
Date d'inscription : 01/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 9:38

I am jealous it would be a dream of mine to work with a great team like aprillia and to be able to spend the time looking for extra power, you get to spend there money. So much better
Revenir en haut Aller en bas
GtG001



Nombre de messages : 81
Age : 64
Localisation : Adelaide, Australia
Date d'inscription : 03/06/2012

MessageSujet: Aprilia RSA   Mer 27 Juin 2012 - 10:27

Having read all of the postings on this topic (gp125-caracteristiques-aprilia-rsa) I get the feeling that it is hard to beat a RSA style rotary valve motor but the KTM has answered the challenge with a Reed Valve motor. As there is very little information about on this motor being posted, can I be bold enough without offending you and ask you if you know how they were able to do this?
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 10:32

Yes, no problem.
Their cilinder and exhaust pipe were copied from Honda.
Their fairing and gearbox were designed by Porsche
Instead of a powerjet they used an injector in the crankcase.
In their last year they had a very good rider, Marc Marquez, but he never won.
When Marquez changed to Aprilia he nearly always won!
Revenir en haut Aller en bas
GtG001



Nombre de messages : 81
Age : 64
Localisation : Adelaide, Australia
Date d'inscription : 03/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 13:09

Jan Thiel a écrit:
Yes, no problem.
Their cilinder and exhaust pipe were copied from Honda.
Their fairing and gearbox were designed by Porsche
Instead of a powerjet they used an injector in the crankcase.
In their last year they had a very good rider, Marc Marquez, but he never won.
When Marquez changed to Aprilia he nearly always won!

The HP quoted in the media for the KTM 125GP is 55HP, do you think this is at the gearbox or crankshaft?
Also, they are quoted as using a 39mm Keihin Carburetor but this seems a little small compared to the Aprilia; do you think it is correct or do reed valve motors work better on a smaller Carburetor?

many thanks for your time.
Revenir en haut Aller en bas
Jan Thiel



Nombre de messages : 470
Age : 78
Localisation : Bangkok
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 13:51

The flow capacity is limited by the reedvalve, not the carburettor.
So it makes no sense using a carburettor bigger than 39.
We tried, of course, but it was not better

55 KTM HP is surely at the crankshaft.
Revenir en haut Aller en bas
Frits Overmars

avatar

Nombre de messages : 2131
Age : 70
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 14:17

Jan Thiel a écrit:
Frits, if you wish you can publish the exhausts sizes at this forum, no problem!
OK, here we go, for all two-stroke addicts: the latest exhaust pipes from Aprilia, Honda, Derbi and KTM.

[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]
Revenir en haut Aller en bas
wax



Nombre de messages : 60
Localisation : australia
Date d'inscription : 01/06/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 14:19

And we all right click, save image as.
Revenir en haut Aller en bas
Howard Gifford



Nombre de messages : 136
Age : 62
Localisation : Ottawa Canada
Date d'inscription : 01/05/2012

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 15:40

Thank you Frits. Im sure there are a lot of snips and torches being used this week as everyone tries these designs. It is very intersting to me that the Aprilia pipe has no parallel center section. This goes against the norm. Was it found that a tapered center carried the negative wave longer thus evacuating more charge through the motor? Also the last section of the difuser cone is very long and has a relatively steep angle. This would indicate a very high suction from this pipe. I am curious as to the name 102Tubo? What does this signify?
Revenir en haut Aller en bas
Marc
Admin
avatar

Nombre de messages : 27643
Age : 60
Localisation : Villiers sur Marne (94)
Date d'inscription : 27/05/2008

MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   Mer 27 Juin 2012 - 16:48

Frits Overmars a écrit:
Jan Thiel a écrit:
Frits, if you wish you can publish the exhausts sizes at this forum, no problem!
OK, here we go, for all two-stroke addicts: the latest exhaust pipes from Aprilia, Honda, Derbi and KTM.






Revenir en haut Aller en bas
http://www.pit-lane.biz
Contenu sponsorisé




MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)   

Revenir en haut Aller en bas
 
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)
Revenir en haut 
Page 37 sur 40Aller à la page : Précédent  1 ... 20 ... 36, 37, 38, 39, 40  Suivant
 Sujets similaires
-
» WANTED TONY "Barbe-rousse"
» Traduction, help wanted
» Wanted Kader
» Bannière Wanted
» Graphiste Wanted

Permission de ce forum:Vous ne pouvez pas répondre aux sujets dans ce forum
 :: ACTUALITES :: [GP] :: [GP125 (et 250 Snif!)]-
Sauter vers: