ESE's works engine tuner

[wobbly]

" And the floor of the transition should be co-linear with the duct entry angle. "

Here is the layout, showing the floor of the transition continues out to the header round diameter at the same exit angle as the duct.
All of the transition angle is in the roof of the usually CNC generated spigot.

Yea well Frits, at the time I was so big headed about myself finding a relationship that worked with the full port exit area, I would never have
even thought that the Blowdown was the real determining factor.
As I said before - we are finding more and more so that the area of the duct below the transfers is becoming less and less ( in size and importance ),in that
the "power" numbers attributed to the Ex port area in various papers from Nomura/Blair/TSR etal , and now still present in EngMod, are basically irrelevant.

[ief]

A picture...

Tnx Wob.

[peewee]

did you guys notice engmod has new stuff added like sharp or bullnose trans entrance and straight or tea cup oh ya and it shows a image of the boyesen ports now

[wobbly]

That was added by Neels as following Mr Thiel ( as usual ) the flow regime of the Aprilia was made so much better by adding a BIG ball nose radius to
the edge formed by the inner transfer duct walls and the bottom of the bore.
Doing this does changes the flow for the better and is proven to make power whenever its done.

[AndreasL]

If the Master (Frits) say you need to do things...you do!

Played a bit within my cramped space for transfers.
What we see is a cross section taken "in the flow direction". (60° from exhaust port as per Wobblys guidelines.)
Not to bad after all considering everything is small in this engine.

The approach, if any one else like to try it, was the following:

- Hights for deck plane (xy = 0), port floor/roof (19 and 29mm) and skirt (-2mm) was set.
- Radial (x) limits set. Liner thickness (~2.5mm) and outer wall limit (16mm).
- Help lines at the port entry. (30° as per Wobblys recommendations.)
- Fit a inner arc, tangential to above mentioned (lower) help line/liner intersection at the top and intersecting the port entry point at the base of the cylinder...or what ever point one think is best.
- Add a radius between the upper, angled, help line and the vertical outer limit line.
- Adjust the outer radius untill you have the min distance between the inner and outer radii just before the outer radius meets (tan) the "roof line".

Any one left reading?
Was it understandable?
Is it even a valid approach?

I think the result is fairly similar to peewees?

Please criticize and add ideas of your own.



In 2D it's not to bad as I said. The problem starts when trying to implement the profile to the 3D world of the cylinder.
For simplicity it would have been nice to keep the need of adding material to a minimum. At least for this one cylinder.

Thanks Frits and peewee for kicking me in the but to take a look at this matter for real.

EDIT: A better picture including as big a ball nose radius as possible as well as the liner thickness.

[JanBros]

a question about the washers next to the rod on the big end :

I'm turning a Honda Sky (SGX50) into a proper MX-moped and welded plates on top of the crankcase to have a bigger intake. I thought I had found the proper conrod (8mm longer) and bought it some time ago, but now it turns out the bloke hadn't put the correct sizes with the add : the big end is 26 and not 24mm

so I need another one and have been looking everywhere but one that would be perfect doesn't excist.
closest would be one that is 13 thick at the big end . The Sky's rod is 12mm thick and has 2 1mm washers next to it. would it be ok to use a 13mm thick rod with only 1 washer ?

[breezy]

If the Master (Frits) say you need to do things...you do!

Played a bit within my cramped space for transfers.
What we see is a cross section taken "in the flow direction". (60° from exhaust port as per Wobblys guidelines.)
Not to bad after all considering everything is small in this engine.

The approach, if any one else like to try it, was the following:

- Hights for deck plane (xy = 0), port floor/roof (19 and 29mm) and skirt (-2mm) was set.
- Radial (x) limits set. Liner thickness (~2.5mm) and outer wall limit (16mm).
- Help lines at the port entry. (30° as per Wobblys recommendations.)
- Fit a inner arc, tangential to above mentioned (lower) help line/liner intersection at the top and intersecting the port entry point at the base of the cylinder...or what ever point one think is best.
- Add a radius between the upper, angled, help line and the vertical outer limit line.
- Adjust the outer radius untill you have the min distance between the inner and outer radii just before the outer radius meets (tan) the "roof line".

Any one left reading?
Was it understandable?
Is it even a valid approach?

I think the result is fairly similar to peewees?

Please criticize and add ideas of your own.



In 2D it's not to bad as I said. The problem starts when trying to implement the profile to the 3D world of the cylinder.
For simplicity it would have been nice to keep the need of adding material to a minimum. At least for this one cylinder.

Thanks Frits and peewee for kicking me in the but to take a look at this matter for real.

EDIT: A better picture including as big a ball nose radius as possible as well as the liner thickness.

makes you wonder how big the bull nose profile could be before it became no longer relative/ and could it be helped by being started inside the piston skirt? (profile inside piston skirt the same as what you have shown in the transfer port....)

[AndreasL]

The Sky's rod is 12mm thick and has 2 1mm washers next to it. would it be ok to use a 13mm thick rod with only 1 washer ?

Why not use 2 0.5mm washers together with the 13mm rod?

[AndreasL]

makes you wonder how big the bull nose profile could be before it became no longer relative/ and could it be helped by being started inside the piston skirt? (profile inside piston skirt the same as what you have shown in the transfer port....)

Think I get what you mean. Interesting thought.
My take on it though is that the piston only spend a very small portion of the stroke at BDC.
So, at BDC it might be a benefit, but overall I would go for the traditional chamfered/radiused piston skirt to promote lubrication.

Do I know for sure?
Absolutely not!

[JanBros]

Why not use 2 0.5mm washers together with the 13mm rod?

where can I buy seperate washers ?
the washers I suppose prevent the rod from wearing into the web, but how come some rods/cranks come without the washers (like the 13mm one I'd like to use) ?

[wobbly]

Jan reported that the Aprilia made no more power by radiusing the piston skirt cutaway area once the bore had the ball nose added.
Ken S has experimented with a heap of piston radiusing, but not I believe in concert with a ball nosed bore as well.
The ball nosed bore has an effect on flow as soon as the transfers are open, so I can see why that is a major influence on power.

[peewee]

frits you can see here how easy it is to make the 2D image. I didn't enter any particular lengths, radius etc because I had to hold the camera but you get the idea. after its finished you can print the image on paper and transfer that to a thin piece of aluminum for the template. if you enlarge the video to full screen you can see better

[peewee]

wob you know how the override transmissions work ? just picked up a 2-5 with N in the down position and billet 2nd gear. ive never seen one before but it doesn't have the same arrangement of gears as a normal trans when I was comparing them

[husaberg]

where can I buy seperate washers ?
the washers I suppose prevent the rod from wearing into the web, but how come some rods/cranks come without the washers (like the 13mm one I'd like to use) ?

Samarin sell them.
http://www.samarin.net/?productos

As do Pro X

Try barikit as well

Some bikes use top guided rods, ie washers at the top, a modernish example is a RGV250

[Frits Overmars]

frits you can see here how easy it is to make the 2D image. I didn't enter any particular lengths, radius etc because I had to hold the camera but you get the idea. after its finished you can print the image on paper and transfer that to a thin piece of aluminum for the template.

It's even easier for me Peewee, because I wrote a dedicated program ages ago. Too bad I wrote it for my own use exclusively, so it's not user-friendly; otherwise I would have made it available here. But your method will do fine.