[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked)

SB07 a écrit:: lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

Thank you Mic and Sb07! According to you, I thought correctly!

Well, PVO if you'd like to copy the RSA, I'm affraid you have to take into account the fact that the pics above are not correct.

But if they are not correct, then I don't understand why did Mr. Thiel say that the direction B (which you can see on the pic called sezione F-F) is the best, while the cylinder RSA on the photo looks like the drawing A?

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Some page before you can find a link and through that you can download Engmod files which contain the cylinder RSA as well. Unfortunatelly the data in that file also has to be false as the flow width of the auxiliary exhaust port is 17,5 mm in it. But it can't be true as it is only the width of the auxiliary exhaust port. Seeing that the width of its flow area only could be 10-11 mm. And it is a huge difference if we'd like to calculate the time-area!

B.

Forgi a écrit:

SB07 a écrit:: lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

Thank you Mic and Sb07! According to you, I thought correctly!

Well, PVO if you'd like to copy the RSA, I'm affraid you have to take into account the fact that the pics above are not correct.

But if they are not correct, then I don't understand why did Mr. Thiel say that the direction B (which you can see on the pic called sezione F-F) is the best, while the cylinder RSA on the photo looks like the drawing A?

]

Some page before you can find a link and through that you can download Engmod files which contain the cylinder RSA as well. Unfortunatelly the data in that file also has to be false as the flow width of the auxiliary exhaust port is 17,5 mm in it. But it can't be true as it is only the width of the auxiliary exhaust port. Seeing that the width of its flow area only could be 10-11 mm. And it is a huge difference if we'd like to calculate the time-area!

B.

I struggle to see how A is better but fortunately for me the only cylinders I've made are CAD models so I can change things if I have to.

PVO a écrit:: I struggle to see how A is better but fortunately for me the only cylinders I've made are CAD models so I can change things if I have to.

I'm sorry, but I don't know either which one is better, cos if I'm right in both cases the port's flow area has the same size, so X. If I'm not wrong basicly the ports transfer the same amount of exhaust gas, don't they? Of course supposing that the auxilliary exhaust port is rectangular.

PVO a écrit:

Forgi a écrit:

SB07 a écrit:: lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

Thank you Mic and Sb07! According to you, I thought correctly!

Well, PVO if you'd like to copy the RSA, I'm affraid you have to take into account the fact that the pics above are not correct.

But if they are not correct, then I don't understand why did Mr. Thiel say that the direction B (which you can see on the pic called sezione F-F) is the best, while the cylinder RSA on the photo looks like the drawing A?

]

Some page before you can find a link and through that you can download Engmod files which contain the cylinder RSA as well. Unfortunatelly the data in that file also has to be false as the flow width of the auxiliary exhaust port is 17,5 mm in it. But it can't be true as it is only the width of the auxiliary exhaust port. Seeing that the width of its flow area only could be 10-11 mm. And it is a huge difference if we'd like to calculate the time-area!

B.

I struggle to see how A is better but fortunately for me the only cylinders I've made are CAD models so I can change things if I have to.

The width of the aux. duct was 13mm and the height 12mm.
The port was not rectangular, to stay away from the transfers as much as possible.
So the underside of the port was inclined, clearly visible on the photo.
It was neither 'A' or 'B', it was curved.

Jan Thiel a écrit:

PVO a écrit:

Forgi a écrit:

SB07 a écrit:: lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

Thank you Mic and Sb07! According to you, I thought correctly!

Well, PVO if you'd like to copy the RSA, I'm affraid you have to take into account the fact that the pics above are not correct.

But if they are not correct, then I don't understand why did Mr. Thiel say that the direction B (which you can see on the pic called sezione F-F) is the best, while the cylinder RSA on the photo looks like the drawing A?

]

Some page before you can find a link and through that you can download Engmod files which contain the cylinder RSA as well. Unfortunatelly the data in that file also has to be false as the flow width of the auxiliary exhaust port is 17,5 mm in it. But it can't be true as it is only the width of the auxiliary exhaust port. Seeing that the width of its flow area only could be 10-11 mm. And it is a huge difference if we'd like to calculate the time-area!

B.

I struggle to see how A is better but fortunately for me the only cylinders I've made are CAD models so I can change things if I have to.

The width of the aux. duct was 13mm and the height 12mm.
The port was not rectangular, to stay away from the transfers as much as possible.
So the underside of the port was inclined, clearly visible on the photo.
It was neither 'A' or 'B', it was curved.

Jan I just want to double check with you that I have indeed modeled them correctly. By what you said I think I have but I want to be sure. Or do they need to be less curved? Thanks for your help.

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senso a écrit:: The RSA crankcase seems to be water cooled, so maybe there is some advantages to cool the lower end of the cylinder, or at least have a more uniform temperature distribuition in the engine perhaps..

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I think you are right in that it would be better to cool the lower end of the cylinder.

romeuh80 a écrit:

Howard Gifford a écrit:: I suspect the designer of Tubo-120 wanted a longer , more agressive reflected wave therefore he designed the baffle cone larger and the result was a slightly tapered mid section.

Good guess, I think aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 771973

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 771973

Yes, exacty!
I already did this on the 50cc Bultaco in 1979 and on the Garelli in 1980, with good results.

PVO a écrit:

Forgi a écrit:

SB07 a écrit:: lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

Thank you Mic and Sb07! According to you, I thought correctly!

Well, PVO if you'd like to copy the RSA, I'm affraid you have to take into account the fact that the pics above are not correct.

But if they are not correct, then I don't understand why did Mr. Thiel say that the direction B (which you can see on the pic called sezione F-F) is the best, while the cylinder RSA on the photo looks like the drawing A?

]

Some page before you can find a link and through that you can download Engmod files which contain the cylinder RSA as well. Unfortunatelly the data in that file also has to be false as the flow width of the auxiliary exhaust port is 17,5 mm in it. But it can't be true as it is only the width of the auxiliary exhaust port. Seeing that the width of its flow area only could be 10-11 mm. And it is a huge difference if we'd like to calculate the time-area!

B.

I struggle to see how A is better but fortunately for me the only cylinders I've made are CAD models so I can change things if I have to.

Please take a look at the picture and design fom Mic, above.
These are correct, do not look at the very old 2D design.

Can we think that the water enters the case will be warmer at the entrance under the cylinder due to the contact of the walls of the gearbox?
Would it not be more interesting to enter the water directly under the cylinder?

fpayart a écrit:: Can we think that the water enters the case will be warmer at the entrance under the cylinder due to the contact of the walls of the gearbox?
Would it not be more interesting to enter the water directly under the cylinder?

You want to keep the crankcase as cool as possible, not only the cylinder!
A friend of me once made a separate cooling system for cylinder and crankcase.
But that proved to be too complicated.

It is also one of my ideas, moreover it might be interesting to have different temperatures for the crankcase and cylinder aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 55116

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 55116

Francis,
would there be any bad effects of having a crankcase too cold ?
(not as cold cold but lukewarm (tiede) )

condensation in the fuel ?, (bad for the oil for the bearings ?)

bad mixing of fuel ?

cheers, david

Nombre de messages : 62 Localisation : Denmark Date d'inscription : 12/02/2012

Jan Thiel a écrit:

PVO a écrit:

Forgi a écrit:

SB07 a écrit:: lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

Thank you Mic and Sb07! According to you, I thought correctly!

Well, PVO if you'd like to copy the RSA, I'm affraid you have to take into account the fact that the pics above are not correct.

But if they are not correct, then I don't understand why did Mr. Thiel say that the direction B (which you can see on the pic called sezione F-F) is the best, while the cylinder RSA on the photo looks like the drawing A?

]

Some page before you can find a link and through that you can download Engmod files which contain the cylinder RSA as well. Unfortunatelly the data in that file also has to be false as the flow width of the auxiliary exhaust port is 17,5 mm in it. But it can't be true as it is only the width of the auxiliary exhaust port. Seeing that the width of its flow area only could be 10-11 mm. And it is a huge difference if we'd like to calculate the time-area!

B.

I struggle to see how A is better but fortunately for me the only cylinders I've made are CAD models so I can change things if I have to.

Please take a look at the picture and design fom Mic, above.
These are correct, do not look at the very old 2D design.

Thanks Jan but I can't take credit for Francis nice SolidWorks drawing aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 771973

But I do have one which is similar.

Jan Thiel a écrit:: Please take a look at the picture and design fom Mic, above.
These are correct, do not look at the very old 2D design.

Dear Mr. Thiel!

I really appreciate your answers, thank you very much.

Of course I understand that the duct was cambered, but the drawings were just figurative, I intended to explain or inerpret the direction of the flow with them.

According to Mr. Overmars pic the duct seems to be like the green line, not like the red one, as you can see it on PVO's drawing. Or is it just an optical illusion?

PVO, could you please show a pic about your plan from the same point of view as the XY pic has?

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This may give you an idea of the way the auxiliary exhaust ducts exit from the cylinder:
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Forgi a écrit:

Jan Thiel a écrit:: Please take a look at the picture and design fom Mic, above.
These are correct, do not look at the very old 2D design.

Dear Mr. Thiel!

I really appreciate your answers, thank you very much.

Of course I understand that the duct was cambered, but the drawings were just figurative, I intended to explain or inerpret the direction of the flow with them.

According to Mr. Overmars pic the duct seems to be like the green line, not like the red one, as you can see it on PVO's drawing. Or is it just an optical illusion?

PVO, could you please show a pic about your plan from the same point of view as the XY pic has?

I've redone my sub ports since yesterday. The first two pictures show my old sub ports. The last two depict my new design. Hope this helps.

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In addition, it is preferable to start as shown by Frits.
And keep material behind to a future amendment
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Nombre de messages : 30 Localisation : Greece Date d'inscription : 09/07/2011

Furthermore, judging from the 3d models I think the AUX exhaust ducts are more like this (left) in RSA

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Yes Vagelis I can confirm that!

Thanks for pointing out all the subtleties in the sub ports. Should I be concerned about the port narrowing at the end as it sweeps inwards or does this not matter much since it is entering into the main port at that point? There is about a 1.5-2mm difference between width A and B in my design with the sweep.

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It would be better to make B equal to A!
That is wat we did.

@PVO
Have a look here: [Vous devez être inscrit et connecté pour voir ce lien] aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 980796

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 980796

fpayart a écrit:: @PVO
Have a look here: [Vous devez être inscrit et connecté pour voir ce lien]

Thank you

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 18 809262

Good Design job, at leats bridge exhaust is simple, I will stay with that lol!

looks a bit like a go boom fast design

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Definitive design Question

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