ESE's works engine tuner

[ceci]

The Honda technicians were quite inventive. It was the Honda board that was against the two-strokes and therefore blocked several promising developments. ​

It is fascinating to study Honda's attempts to find a solution to the 2S problems, it has a large number of documents on its pneumatic injection system in English "patents, SAEpapers", best of all it is a 158 page university thesis in JAPANESE . In the thesis, in addition to analyzing their injection system, they analyze the DITECH, making a 250cc prototype with that injection system, to compare with their system on the same mechanical basis.

[porttiming124]

Good morning. I have a question regarding the text that Wayne wrote. (Crap transfers can easily be subjected to "over scavenging " a term coined by Erv Kanemoto about trying fatter pipes on a TZ750 when going from 100 Dia up to 110 Dia.
That is the overly efficient steeper angled diffuser looses more power to short circuiting than it makes power by better scavenging.)
On the dyno if we measure the airflow, will we see the airflow raised and the hp going down in the case of the example of the 110 mm tune pipe in your opinion?

[wobbly]

Yes , the Delivery Ratio may rise due to the more efficient scavenging action of the diffuser , but at the same time the Trapping Efficiency can drop even more - lifting mass airflow , but loosing power.

[porttiming124]

ok thank you

[lodgernz]

Attachment 354417 Attachment 354418

Our interpretation of Woblys idea of having the outer edges of the T port the highest.

Not sure if this is correct, Wob and the Dyno will tell us soon enough I guess.

Any progress Rob?

[TZ350]

Any progress Rob?

No, but maybe shortly as we are getting the bikes ready for the dyno before heading down to the GP.

Pinky, the bike with the newly raised eyebrows also has a habit of shaking its cylinder loose. 50% balance factor so not sure what is happening there? Maybe deto as Wob suggested.

[lodgernz]

Wobbly,
a number of times in this forum, you have recommended that when cutting and rotating pipe segments to achieve the appropriate curve, the cuts should be at no more than 7º.

I've been assuming that refers to the actual cut, not the resulting deviation in the pipe, which would be 14º.

Am I correct, or should we be limiting the deviation to 7º, with a 3.5º cut?

[Frits Overmars]

Wobbly,
a number of times in this forum, you have recommended that when cutting and rotating pipe segments to achieve the appropriate curve, the cuts should be at no more than 7º.
I've been assuming that refers to the actual cut, not the resulting deviation in the pipe, which would be 14º.
Am I correct, or should we be limiting the deviation to 7º, with a 3.5º cut?

If you want show pipes with a zillion blue-colored 'titanium' welds, go for the smallest angle and the most segments and the most labour.
If you want functional pipes, do not exceed the 7° cut angle that gives you the 14° centerline deviation angle.
A bit of hammering after each weld will yield an acceptable appearance.

[wobbly]

Frits gets the Girl Guide Badge for this weeks reply.

[lodgernz]

If you want show pipes with a zillion blue-colored 'titanium' welds, go for the smallest angle and the most segments and the most labour.
If you want functional pipes, do not exceed the 7° cut angle that gives you the 14° centerline deviation angle.
A bit of hammering after each weld will yield an acceptable appearance.

Thank you Frits and Wobbly.
If you saw my welds, you'd want the fewest possible, to reduce the pain on your eyes.
I usually make the two headers, and sometimes the first diffuser, by hydroforming (all separate), so the cut-and-rotate technique is less required.

[Condyn]

Not an attempt to cut off Frits, as his 7 degree rule is most likely tested and accurate, but I like to use 7.5 degrees as max, simply because thinking about fives and zeros when it comes to angles is easier than fours and eights.

Here is one I recently did that uses 2.5 degree cone ends for a total of 5 degree junctions for the first few sections, then it goes to 5 degree cone ends, and finally 7.5 degree cone ends for the diffuser hook. This keeps the head pipe more straight, and using multiples of 5 keeps things quick and easy for the layout method that I use.

The cheap Cone layout software eliminates the need for cutting and turning, which shortens your pipe and has to be accounted for in the design process. You do need to add the material thickness to your diameters in cone layout as we have found them to be that much smaller after final measurements.

[wobbly]

Seems at odds to me using a superb sim code to design a pipe within 1/10ths of a mm and then hand cut or use crap sheetmetal software to bend the things around the corners.
Using SolidWorks the cut flat laser patterns shapes are perfect as are the finished diameters.
Its easy to define a cone centerline , and sketch in the assembly any contact points such as a frame - plus all the rolled cone section joints are all in line , making assembly easy and repeatable.

The cut angles certainly do make a difference - as I was told to test this in a KZ pipe design process.
I had several cuts at 8* and I had all the seams around the outside of the single main bend - simply making the longer cone joins easier to align dead true.
The request was to reduce the max bend to under 7* ( adding a cut ) and putting the seam on the inside of the 12 cuts.
I did this and back to back it gained 1.5 Hp in 48.

[TZ350]

Attachment 354417 Attachment 354418

Our interpretation of Woblys idea of having the outer edges of the T port the highest.

Not sure if this is correct, Wob and the Dyno will tell us soon enough I guess.

Any progress Rob?

Ok, we got it the dyno tonight. Outer edges start opening at 78deg ATDC and the exhaust port is full open at 80deg ATDC.

Made better power than it did before, but we also made some other changes so the results of razing the outer edges of the exhaust port can't be fully credited for the extra power and range. But at least they did not completely kill the engine.

[karter444]

Hi What is it about a 100 cc direct drive reed or rotary kart engines design that allows it to rev to 20,000 quite happily all day .
cheers

[wobbly]

Short stroke , very light reciprocating parts , and a rebuild every hour if you are lucky.