If it's a rule of thumb, I think 3-5* delay ie. double total, for the aux goes.
Hardcore Biker
If it's a rule of thumb, I think 3-5* delay ie. double total, for the aux goes.
Scooter boy
Thank you andreas. That is around 2 mm, then I still have a bit of margin.Originally Posted by andreas
Hardcore Biker
That's no where as bad a mistake as filling the tank with gasoline only, no oil mix. That's really hard on an engine at 15,000 rpm or so when the piston seizes.
Lohring Miller
Hardcore Biker
expand boosters to increase blowdown
quick superimposition with photoshop of the pvp cylinder (Aprilia copy) portmap with that of the 122 cylinder the setting of the port heights is not respected.
It gives you an idea for the shape of the ports.
Scooter boy
Merci philou!
That will be a good inspiration. I am limited by a piston pin without plugs, but there is plenty of mm2 there.
Hardcore Biker
I did not raise the engine myself or create the engmod2t file. so to check on a cylinder in real life.
data on transfers and TA values of the stock cylinder.
a lot of work on the transfer ports. widen the B backwards and angle upwards for A and B
Scooter boy
Merci philou!
My plan is to raise transfers 0.6 mm and I will try to do the angle upwards too. With the tools I have, I can widen the B transfer only a bit. Do you know if there is a benefit on widen C transfer too?
Hardcore Biker
the C is already too wide
the B deserves to be widened to a close to the C
on the file the B (12°) has an upward angle greater than the A (5°).
it has to be the other way around.
why do you say you don't have enough blowdown?
Scooter boy
Merci philou, I will not touch C then, and will work on B as much as I can. I need the blowdown for matching the transfer sta increase. I did some calculations with Janbros spreadsheet and that was output.
Hardcore Biker
You want to have as much area as possible. If the rings are to stay in the same location, naturally there is a potential benefit from widening the c an b port respectively.
Hardcore Biker
to choose in my opinion, it is better to work on the efficiency of scavening even if it means losing a bit of surface.
enlarge the C even more, will decrease its effectiveness
Hardcore Biker
the greater the angle of a port, the smaller it's effective flow area.
so widening the C-port (for example 4mm) by the same amount as widening the sum of the B-ports (for example eacht B-port 2mm) generates less extra TA than widening the B's,
and keep an eye an the angle of the scavenging column while changing the ports so that you do not end up with a crzay angle.
and don't mkae the angle of the A's to big, as the higher if flow's , the easier it can flow straight out the exhaust.
Hardcore Biker
Obviously this is the case, but it didnt seem like he was about to change the ring-pegs locations.
L-Plate Rider
I believe some numbers in your calculation are not right.I did not raise the engine myself or create the engmod2t file. so to check on a cylinder in real life.
data on transfers and TA values of the stock cylinder.
a lot of work on the transfer ports. widen the B backwards and angle upwards for A and B
Total Port Transfer area sum = 834.91 (not 940.14).
Eff. dia area 852.13 = 32.94 (not 34.85).
Eff. dia area 1019 = 36.02 (not 37.78).
Eff. dia area 132.62 = 12.99 (not 17.16).
In that case results as 10.500 rpm also can't be right, or am I wrong?
Hardcore Biker
unfortunately when there is an image, people don't read the text.
it is a file found on the internet. I insist on checking on a real cylinder that the data is correct.
http://adardaine.free.fr/file/Aprilia_RS125.zip
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