ESE's works engine tuner

[Muciek]

Francis Thank You very much, 2nd picture is exactly what I was looking for.

[2T Institute]

Hello,

You will find hereafter some informations about THE Rotax 256.
The valve diameter is 124 mm
There is two kind of valve: Opening 162 ° or 170 °

Attachment 324906

Attachment 324904

Attachment 324905

Regards.

Francis.

Merci Francis I must have some untouched cases 34 high x 40 wide.

Can you tell us what happened with the Aprilia RS 125/FPE project?

https://www.youtube.com/watch?v=feFhdLe7oNI

[_____]

Hi Frits, Jan, Wobbly and everyone :-)

I got a question regarding discharge values:
Has anyone determined the cd values of exhaust ports? Similar like it was done to the QUB SAE-Paper
2003-32-0029.
Nevermind if CFD simulated or measured (and re calculated) on a flow bench.

If I remember correcty: Frits, you made the exhaust port of the F2 with an automatic cd-value controled CFD tool?!

@Jan, was CFD used to design the exhaust port of the RSA? I remember that I have read it was done with a flowbench?

Cheers and thanks
Chris

[Frits Overmars]

What is an F2?

[_____]

What is an F2?

Oh, sorry. My bad.
I must have remembered it wrong - thought this was the name of the outstanding glowplug plane engine you have designed?

[Frits Overmars]

Oh, sorry. My bad. I must have remembered it wrong - thought this was the name of the outstanding glowplug plane engine you have designed?

You remembered it right; I did not remember it at all because it was 14 years ago but it has come back now. It was the Profi F2A. And I did not design that engine; I only did some ducting and piping for it, using a home-brewn CFD program. The F3D was the engine I did some more work on.

Re your question about the Cd values of exhaust ports: that would not be just a number, but a whole list per port with a CD-value for each crank degree.
I never tought my program to put out such a list; what I needed was mass flow behaviour and a points cloud describing the duct geometry.
Below you see the points cloud, the corresponding 3D-solid and the copper electrodes used to spark-erode the exhaust duct in the prototype F3D engine.


Jan did flow tests stepping through the piston positions, using the contraption shown below.

[jfn2]

wobbly;
Thank you very much for the info on wall temps. Where on the pipe would be the best place to mount a single sensor or do you have to monitor different places and where would they be and how many? My data collector only has 4 temperature outputs. I am using one for egt, one for water temp, and one for cht leaving one more.

adegnes:
I'm looking forward to seeing your temp readings. Thanks

[adegnes]

adegnes:
I'm looking forward to seeing your temp readings. Thanks

I'm afraid you'll have to wait a bit longer for my numbers.
On the dyno the translucent float bowl revealed massive fuel foaming throughout the powerband, nothing but foam in the bowl.
Is vibration the only probable cause for this? I mean it's not that bad, I've experienced far worse without this foaming issue.
I also tried the added weight, the brace, and holding it with my hand again, now with the clear bowl, made no difference.

Running 98pump with 5% a747

[wobbly]

What you are after is the average temp of the pipe wall material.
You would need to measure the hottest ( at the header ) then the coldest ( in the mid ) - then it gets hotter again as you travel down the rear cone.
Problem is that there is far more area of cold surface in the middle, so sadly some fudge factor guesstimating is needed.

Re the foaming fuel bowl, as I said before the crank balance is wrong for this to even begin to happen at all.
Fuel tank anti surge foam would help in the bowl, but you need to fix the actual issue.
It sounds like some part of the out of balance force is combining with the 2x crank speed secondary vibration modes.

[jfn2]

Again thank you wobbly for the temp information. I suppose I could do with out the water temp sensor and run two surface temp sensors. I'll try it.

[adegnes]

Re the foaming fuel bowl, as I said before the crank balance is wrong for this to even begin to happen at all.
Fuel tank anti surge foam would help in the bowl, but you need to fix the actual issue.
It sounds like some part of the out of balance force is combining with the 2x crank speed secondary vibration modes.

Thanks, I'll have to read up on the subject.
Maybe the steel rotary valve is part of the problem? The crank itself has relatively low inertia, the variator too, and there's no flywheel.

[FastFred]

Thanks, I'll have to read up on the subject.

Describes how to find the reciprocating weight

Looking at the connecting rod it is easy to see that the Big End goes round and round and is all rotating mass. And the little end and piston goes up and down and is all reciprocating mass.

A simple but very effective jig for statically balancing a crank, that you can make yourself in 10min's.

The KISS method of balancing a single cylinder 2 or 4-stroke.

Its all in the pictures:-

Pic-1 Find the total reciprocating Weight (Mass)
Pic-2 Find the Little Ends reciprocating Weight (Mass)
Pic-3 Find the Balance Facter (Ie. 65% is 0.65 X the ToTal Reciprocating Weight (Mass))
Pic-4 Leave the Little Ends reciprocating Weight (Mass) on the Scales
Pic-5 Attach the rest to the crank.
Pic-6 Balance the Crank.

From Phill Irving. page 109 "the wheels will roll freely along the straight-edges and show no tendency to settle in any one position; if not, the pin will go to the top or bottom according to whether the Counter Balance is to heavy or to light. Correction is usually made by drilling the rims."

Measuring the balance factor of our Suzuki GP125,s
The round bar is very nearly as good as knife edges.
Pic-1 Finding the counter balance by hanging washers of a hook attached to the conrod.
Pic-2 Determining the mass "C" of the counter balance.
Pic-3 Determining the mass "R" of the reciprocating weight.
The balance factor B = C counter balance mass divided by R reciprocating mass.
The balance factor is.......B = C / R
As measured by me, it turns out that the balance factor of:-
A standard Suzuki GP125 is 69%
A Standard Suzuki GP100 is 76%
A GP with alloy plugs in the counter balance holes becomes 58% for the 100 and 52% for the 125.

When we recently dyno'ed two of our bikes with cranks that had the same 69% balance factors. The RS frame vibrated much more than the original GP frame did.

For us this supported the notion that there is no one correct balance factor, as the right balance factor is the one that works with the frame that the motor is mounted in.

............. A lot more info about single cylinder crank ballancing and "how too" pictures in the original posts

[adegnes]

............. A lot more info about single cylinder crank ballancing and "how too" pictures in the original posts

Thank you! But...
I did measure the balance factor earlier(following TZ's instructions), and raised it from below 25% to 38% - the highest I can get it without mallory slugs.


What I need to learn more about is the vibration modes, are we talking about torsional vibration here?

[wobbly]

You dont need to read anything, read my lips "if the cylinder is near vertical then you need a balance factor closer to 60% ".
What im saying is that your engine is currently so far wrong, of course it will froth the bowl, buzz your balls,and make your eyes drop out.
Any vertical single balanced to 40% is a complete waste of your time running it at all.
Low inertia of the crank/variator and no flywheel makes the situation WORSE, due to lack of mass damping.
Just buy the Mallory and get on with it - believe the people that have been there, done it, collected the $100 and didnt go to jail.

I recently tested a single kart engine on my dyno that was balanced at exactly 40%, it was impossible for me to hold the dyno throttle lever as it
hurt so much,it broke off the CHT/EGT leads, wreaked the dyno's digital speed pickup, and funnily enough - fuel spewed constantly from the overflows.
That engine wasn't considered seriously at all to be a replacement for our junior kart classes.

[adegnes]

You dont need to read anything, read my lips "if the cylinder is near vertical then you need a balance factor closer to 60% ".
What im saying is that your engine is currently so far wrong, of course it will froth the bowl, buzz your balls,and make your eyes drop out.
Any vertical single balanced to 40% is a complete waste of your time running it at all.
Just buy the Mallory and get on with it - believe the people that have been there, done it, collected the $100 and didnt go to jail.

Consider it done!