ESE's works engine tuner

[SwePatrick]

Might have misunderstood, someone was talking about honing after coating.
But, is it really smart to have a really really fine Ra?
Oil won´t be transported as with crosshatch honing, and it maybe will make the rollers slide instead of rotate with disaster as result.

[Muhr]

”Rolling contact bearings have to be lubricated in addition to having exceedingly good surface
finishes.

The life of a rolling element bearing depends to a large extent on the smoothness of the
contacting surfaces – the balls, rollers, and races. Typical surface roughness dimensions for
production bearings are as follows:

Balls 2– 3 μin rms
Ball races 6–10 μin rms
Rollers 8–12 μin rms
Roller races 10–20 μin rms”

Here is a pretty good video on the subject, he has made many interesting videos.

https://www.youtube.com/watch?app=desktop&v=JCM2YHcd8kU

[Peljhan]

Did anyone saw video on FB?

https://www.facebook.com/jan.thiel.9...33939527326518

It's birth of Aprilia RSA

I remember Jan comment about this. (see attachment). We can see they are inspecting oil leak mentioned.

Somewhere he also said, that bottle of champagne was opened, probably on facebook and I can't find it

Pure gold!

[Frits Overmars]

Did anyone saw video on FB?
https://www.facebook.com/jan.thiel.9...33939527326518
It's birth of Aprilia RSA
I remember Jan comment about this. (see attachment). We can see they are inspecting oil leak mentioned.
Somewhere he also said, that bottle of champagne was opened, probably on facebook and I can't find it

Here are two links you can try.

https://www.facebook.com/jan.thiel.9...3939527326518/
https://www.facebook.com/groups/2659...2311541581729/

The actual opening of the bottle is not in the video, but handing out the champagne (in plastic cups) is.

[Haufen]

Did anyone saw video on FB?

https://www.facebook.com/jan.thiel.9...33939527326518

It's birth of Aprilia RSA

Thanks!
I am totally into that clutch lever for the dyno operator at 8:45min in the video!

[wobbly]

Muhr , one thing many dont realise is that the rod bores and the pin surfaces dont wear significantly at all.
I routinly replace the big end cage /rollers/washers 4 times in a crank using the same pin and rod.
Its the cage that eventually wears off the silver coating , allowing the rollers to skew , then skid then fail.
After 4 replacements you can just start to measure wear on the pin and rod bore - but hey , they are real smooth by that stage.

One other benefit is that by pressing out opposite sides each time , this helps to maintain the crankwheel press fit , as eventually after multiple pin replacements the pin hole bore relaxes
its interference value.
I noticed the Pankle silly money capped small end pin in your post , this is easy enough to do youself if you can do the cad drawing and have the caps CNC machined , then laser welded in.
The laser guy here has a standard charge , and will do one or 5 pins for the same money.

[jamathi]

Here are two links you can try.

https://www.facebook.com/jan.thiel.9...3939527326518/
https://www.facebook.com/groups/2659...2311541581729/

The actual opening of the bottle is not in the video, but handing out the champagne (in plastic cups) is.

It was 1 of the better days in my life....

[Frits Overmars]

It was 1 of the better days in my life....

There have been ups and downs, but I like to remember the ups, even the small ones. Like when you discovered that I could bake the best fries you ever tasted?
And the invention of my clock-driven parking disc that allowed us to leave the car in a one-hour-spot in Bergamo all day long .
And how we found five horsepower just by bypassing a coolant pump (must be our only good memory of that scrap-metal tout) .

[Muhr]

Muhr , one thing many dont realise is that the rod bores and the pin surfaces dont wear significantly at all.
I routinly replace the big end cage /rollers/washers 4 times in a crank using the same pin and rod.
Its the cage that eventually wears off the silver coating , allowing the rollers to skew , then skid then fail.
After 4 replacements you can just start to measure wear on the pin and rod bore - but hey , they are real smooth by that stage.

Yes, I guess you can run a connecting rod bearing for quite a long time under the right conditions. myself, I have been in the habit of switching with fairly dense intervals. It has been a precautionary measure that dealt with if the connecting rod was subjected to something like e.g. fatigue cracking, ductile fracture
or yielding that could affect the breaking limit of the connecting rod.
Probably completely unfounded in many cases.
However, we have done some tests recently where we stretch these limits, to see what you can learn.

I noticed the Pankle silly money capped small end pin in your post , this is easy enough to do youself if you can do the cad drawing and have the caps CNC machined , then laser welded in.
The laser guy here has a standard charge , and will do one or 5 pins for the same money.

Nice! I can imagine that they (pankle) must have had a similar approach.

[breezy]

A couple examples of incomplete knowledge.

First we "know" that a thin edge orifice plate has a coefficient of discharge of around 0.6 i.e. it flows terrible, and of course other unfavorable shapes have fairly poor coefficients as well.

Second we "know" that once a pressure ratio of about 0.528 is reached on the low pressure side of a non-diffused opening then decreasing the pressure on the low side further will not result in any additional mass flow.

This information is readily available, but it is incomplete. Both only apply to specific scenarios, and there are scenarios inside an engine where neither statement holds true. Some people know this, but I suspect it is not common knowledge ?

so... your exhaust findings.. you have a graph showing a close comparison to a two stroke exhaust pressure wave...without it looking like a two stroke exhaust pipe..is that a header shape or complete system . are you able to show this shape in a picture or? does the 4 stroke system have a length which is similar to 2t tuned length?

[OopsClunkThud]

A couple examples of incomplete knowledge.

First we "know" that a thin edge orifice plate has a coefficient of discharge of around 0.6 i.e. it flows terrible, and of course other unfavorable shapes have fairly poor coefficients as well.

Second we "know" that once a pressure ratio of about 0.528 is reached on the low pressure side of a non-diffused opening then decreasing the pressure on the low side further will not result in any additional mass flow.

This information is readily available, but it is incomplete. Both only apply to specific scenarios, and there are scenarios inside an engine where neither statement holds true. Some people know this, but I suspect it is not common knowledge ?

Been trying to model and optimize the shape of a single exhaust port (I know...) to utilize all the tips, tricks, and concepts brought up here, and I think I know the limitations you are referring to (would still be better to just come out and say it, rather than hint and see if anyone can figure it out). disclaimer: I'm no expert in compressible flow.

1. The 0.6 value is valid for incompressible fluids, but for compressible sonic flow the Cd of a sharp edged orifice goes to 1 as the pressure difference goes higher. so the sharp edge flows better through most of the blowdown phase. discussion of this can be found here: https://www.eng-tips.com/viewthread.cfm?qid=51260

2. the 0.528 value applies when the low pressure side is 0 (a vacuum), there is no lowering it lower. in that limited case the mass flow rate is choked. in all other cases it's the velocity that is choked, but changes in pressure can still get more mass through at a higher density. discussion of this can be found here (think it was linked some time earlier too): http://www.therebreathersite.nl/04_L...ads/Choked.pdf

Also of note is that a thin orifice is never really fully choked. The fact that unlike an intake bell where the radius is outside the bounds of the port diameter, a radius applied to an exhaust port has to fall mostly inside the area of the port opening or it will change the timing.

I've started a simulation project to characterize the flow at pressure ratios we see from exhaust port open to the end of blowdown, as well as fully open at BDC. Figure having a working and validated simulation of a standard configuration that matches our conditions would be a good starting point for simulating actual exhaust ports. https://www.simscale.com/projects/Oo...e_plate_-_cfd/

Here are images of three exhausts, with square edge, rounded port top, rounded port top and piston edge. this led me down this rabbit hole.

[wobbly]

Patrick , one concept I have always wanted to try on a single port ( very rare , work wise nowdays ) is to add concave hooks on the sides of the duct above TPO.
The shape as is common on T port outer edges - that increases considerably that ports Cd value.

[OopsClunkThud]

concave as in adding a side wall angle to the port as pictured below?



If so, I've been trying to model this in engmod as a bridged exhaust with a 0 width bridge. Actually started down this path trying to figure out how much side wall angle to add. Clearly the effective port area would be between 0° side wall as the min, and a radial angle with the area of the curved port face (adjusted for down angle of 25%) for the max. I think that will be the last and largest part of this study.

[jamathi]

There have been ups and downs, but I like to remember the ups, even the small ones. Like when you discovered that I could bake the best fries you ever tasted?
And the invention of my clock-driven parking disc that allowed us to leave the car in a one-hour-spot in Bergamo all day long .
And how we found five horsepower just by bypassing a coolant pump (must be our only good memory of that scrap-metal tout) .

Nice memories indeed.....
But how was I stupid enough to go work for a metal scrap fool?
Mainly to help Daniele Agrati sell his 'reparto corse'....
While MANY people were telling me to go to Aprilia. for years.....
When I finally went there my 'dreams came true'
Many people working there, money enough!
But the nicest place I ever worked was DERBI, only that it was too small.
But I am really proud of the engine we made there....

[wobbly]

Frits , it immediately comes to mind only a Dutchman would use his brain hard enough to invent a clock driven parking disc.
Maybe sell the idea to KTM to patent it while they have a go at MK2 TPI.