ESE's works engine tuner

[Javier Ruda]

I looked for data on the internet to be able to reflect and help him in his request.

And It was useful indeed, to imagine where to add mm2. However it may be from another version of Rotax 122 cylinder. Mine is 220H, part number 223618, and the exhaust port is 29.5 mm tall in example.

[andreas]

Rotax 122

On the Rotax 122 the cylinder with the number 223618 (220H) is installed. Again, there are inscriptions “Gilardoni 1” and “Gilardoni 2”, now on the side of the reed valve case, but the cylinders are identical. The cylinder is also available without the milled slot for the power valve.

Support Channel (Gilardoni 2)
Support Channel (Gilardoni 1)

Cylinder 223618 220H aprilia with support channel

Doesn't help much but it's a portmap.

[Javier Ruda]

Doesn't help much but it's a portmap.

Thank you andreas. Very interesting. My cylinder has B and C top edges at same height though.

[HenkS]

That is from a very old version of the EngMod2T preprocessor, Dat2T and is probably about 15 years old.

No.

I did not design the engmod2t software, Vannik designed and developed it.

I didn't make the file either.

as no information was communicated by the applicant.
I looked for data on the internet to be able to reflect and help him in his request.

For me, it's about trusting data from any program. Not every program can be trusted blindly, and simple mistakes, such as in this example, can easily be made and can have major consequences.
This old Engmod2t, is an example of this. Old version or not but add numbers must still be correct and a diameter calculation must still be equal to the area in mm2.

[TZ350]

Having ruined the last RG50 cylinder and head insert. I figured I would make my own insert with some added features.

As the new cylinder is going to be razed 2mm with a packer to get the port timing right. Instead of trimming the top of the cylinder I plan on spigotting the insert into the cylinder. I have heard that using a spigot has a beneficial effect on over rev detonation.

And instead of a smooth combustion chamber water jacket wall I thought I will add fining to help with waste heat transfer from the combustion chamber and plug area to the cooling water. Does the fining look like a good idea or waste of time or worse, likely to cause problems? Comments welcome. I would love to hear from anyone who has tried this.

[Vannik]

For me, it's about trusting data from any program. Not every program can be trusted blindly, and simple mistakes, such as in this example, can easily be made and can have major consequences.
This old Engmod2t, is an example of this. Old version or not but add numbers must still be correct and a diameter calculation must still be equal to the area in mm2.

I agree, the EngMod2T numbers will not change if the input is the same, the later version gives a lot more data. If the data is not right that was used as input I cannot help.

[philou]

Old version or not but add numbers must still be correct and a diameter calculation must still be equal to the area in mm2.

I never paid attention to this given in engmod.
This calculated surface may be the surface corrected by the angles. giving an effective surface and not a geometric one.

which would seem false, whereas it is what interests us mainly

[husaberg]

I have managed this reverse pipe ok. Single cylinder 360cc, YZ 250X gearbox. Just double it up.

doz piss

the cams will be melted choc but the engine will not have lasted long enough to wear the gears.

[HenkS]

I agree, the EngMod2T numbers will not change if the input is the same, the later version gives a lot more data. If the data is not right that was used as input I cannot help.

I never paid attention to this given in engmod.
This calculated surface may be the surface corrected by the angles. giving an effective surface and not a geometric one.
which would seem false, whereas it is what interests us mainly

It looks like you both don't understand what I mean, but I will try it again.
They are simply conversion errors from surface to diameter.
At the underside of the EngMod2T picture of philou.

EXHAUST PORT.
main port eff.dia 34.85 = Area 852.13 is wrong.
auxillery eff.dia 14.58 = Area 166.87 is right
total port eff.dia 37.78 = Area 1019.00 is wrong.

TRANSFER PORT.
Port 1 eff.dia 24.99 = Area 488.58 is right.
Port 2 eff.dia 16.68 = Area 213.71 is right.
Port 3 eff.dia 17.16 = Area 132.62 is wrong.
Total Port Area = 940.14 is wrong..


All together 3 eff.dia's are right and 3 are wrong.
Total transfer area is also wrong.

It has nothing to do with corner corrections or with the input.

[andreas]

It looks like you both don't understand what I mean, but I will try it again.
At the underside of the EngMod2T picture of philou.

EXHAUST PORT.
main port eff.dia 34.85 = Area 852.13 is wrong.
auxillery eff.dia 14.58 = Area 166.87 is right
total port eff.dia 37.78 = Area 1019.00 is wrong.

TRANSFER PORT.
Port 1 eff.dia 24.99 = Area 488.58 is right.
Port 2 eff.dia 16.68 = Area 213.71 is right.
Port 3 eff.dia 17.16 = Area 132.62 is wrong.
Total Port Area = 940.14 is wrong..


All together 3 eff.dia's are right and 3 are wrong.
Total transfer area is also wrong.

It has nothing to do with corner corrections or with the input.

Maybe the area of the main exhaust port represent it's blow down area, and is it not possible that the third transfer port is corrected for the entry angle, as Philou suggests?

[TZ350]

TRANSFER PORT.
Port 3 eff.dia 17.16 = Area 132.62 is wrong.
It has nothing to do with corner corrections or with the input.

Is the angle of entry to the cylinder influencing the eff.dia calculation compared to the measured area at the face of the port? In your example, Port eff.dia and Area, they could both be right.

[wobbly]

TZ350 - dont spigot , unless the material extending into the bore is a press fit , the edge of the squish step will overheat and create deto.
Even then, if the bore is chromed you have another heat flow barrier surface.
The basic idea is to find a way to keep the plug threads and the area above the squishband cool - but keep the back of the combustion chamber hot.
TM have the chamber back enclosed in a solid step , that presses into the cover - but this keeps water away from the threads as well , unless you do some jiggery to have water flow accessing just in that area..
Its very easy to have the inner surface of just the bowl ceramic coated to reflect combustion heat back into the gas and not wasted by disappearing into the water system.

Edit - fins on the back of the chamber is just simply not right - the marketing gobbledygook " coolhead " comes to mind as plain old masturbation.
\.
Edit - port areas must always be quoted as the geometric area X the Cosine of the up or down angle - EngMod does this as should any port calculator.

[Frits Overmars]

As the new cylinder is going to be razed 2mm with a packer to get the port timing right. Instead of trimming the top of the cylinder I plan on spigotting the insert into the cylinder. I have heard that using a spigot has a beneficial effect on over rev detonation.

TZ350 - dont spigot , unless the material extending into the bore is a press fit , the edge of the squish step will overheat and create deto.

Wob is right. And it will be even worse if the outer edge of the squish band is shaped to cooperate with a radiused piston timing edge. My solution is to spigot the head insert alright, but in a bigger diameter bore. This way the insert won't have a sharp outer edge.

[Flettner]

TZ350 - dont spigot , unless the material extending into the bore is a press fit , the edge of the squish step will overheat and create deto.
Even then, if the bore is chromed you have another heat flow barrier surface.
The basic idea is to find a way to keep the plug threads and the area above the squishband cool - but keep the back of the combustion chamber hot.
TM have the chamber back enclosed in a solid step , that presses into the cover - but this keeps water away from the threads as well , unless you do some jiggery to have water flow accessing just in that area..
Its very easy to have the inner surface of just the bowl ceramic coated to reflect combustion heat back into the gas and not wasted by disappearing into the water system.

Edit - fins on the back of the chamber is just simply not right - the marketing gobbledygook " coolhead " comes to mind as plain old masturbation.
\.
Edit - port areas must always be quoted as the geometric area X the Cosine of the up or down angle - EngMod does this as should any port calculator.

Kinda like this? Next time I have it apart Ill machine fins around the sparkplug root. The top cover acts like a gate and forces all the water through these grooves, machined just above the squish area.

[DoldGuy]

Wob is right. And it will be even worse if the outer edge of the squish band is shaped to cooperate with a radiused piston timing edge. My solution is to spigot the head insert alright, but in a bigger diameter bore. This way the insert won't have a sharp outer edge.

Frits/Wobbly,

The previous GasGas design used the “Spigot” design, are they also prone to detonation? I hate to assume, but the detonation mentioned is caused by end gases escaping between the head and cylinder bore? If memory serves the Wiwa also used this design.

50E33258-93F2-4CD8-B9B0-9112D6D8239B.jpeg (182.9 KB)