ESE's works engine tuner

[husaberg]

Came accross this not read it
https://www.scribd.com/document/7948...Report-Updated

Years ago i had a set of docs
it was most of what i had found Jan and Frits and others wrote about different topics. Mainly from KB pitlane and some other other dutch forums
It was lost in a lightning strike destroyed a computer and the back up. a few years back i might see if i can recover it.

I think i might have shared it with others?

[wobbly]

Having done hundreds of sims for differing engine projects, one of the many " trends " I have noted is that in a reed engine, especially anything that runs to high rpm's
is that as you increase the case volume, the petals need to be made thinner, thus lowering their 1st Mode Natural Frequency.
This then reaches a point where, even with effective curved stopper plates, the petals loose control and go spastic - smashing into the stops and bouncing off them.
In a sim, running the Inlet dialogue , you can see the tip lift being erratic from one run iteration to the next.
When this happens power drops at that rpm.

The CCR for a reed seems to be limited to about 1.3 - that gives enough volume for the pipe to draw from, and also allows petals thick enough not to go out of control.
But many larger displacement cylinders like a value slightly larger than this ie a smaller case.

EDIT - I have just read the spec sheet above and the Rotary Valve timing is well different from what Frits has given us at 152.5/90. Closing at 88 is the lowest number I have ever seen quoted.

[speedpro]

Off topic but I had a bit of a chat with SS90 at the 2026 NZ Grand Prix meeting 3&4 Jan at Ruapuna. Not who I expected at all.

[Rudex]

Wob/Frits

Can you say me what is the sense of using Bushing Bearing Modena KZ kk1? and if it would be better to use plastic insert in whole case (around the crank too) or like kk1?.
Why didn't they just machine the crankcase?




Regards

[JanBros]

if the bearring gets lose in the case, you don't have to buy a new expensive crankcase, but simply change the inexpensive bushing ?

[Frits Overmars]

You have wrote far more and we are greatfull for everpart thats just little what a quick search turned up.
That last translated part i had never seen before? I never had a chance to read it. My own german is limited to what was in comics.
looks like it was indeed translated from something your wrote in 2009 translated using google and posted by RN? 2019?
Ignition Curves Copyright 2009 Friits Overmars - (translated via google translate and some manual editing RN Jan-201999
here is another verson
looks closer to english
https://opensimspark.org/_media/fos-...curves-eng.pdf

Yes, that last version, translated with Deepl, does look more like the king's English; not bad at all.
In case you wish to compare it to the original text and at the same time brush up your German a bit:

[katinas]

the petals need to be made thinner, thus lowering their 1st Mode Natural Frequency.
This then reaches a point where, even with effective curved stopper plates, the petals loose control and go spastic - smashing into the stops and bouncing off them.

Just add illustration of your words for more clear imagination of what might be happening with the reeds (free oscillating) .

[flyonly]

54 x 54 twin port cylinder underway. Rear disc valve this one, this is for Vinduro so is 125cc.
This same setup ( bottom end) with a smaller cylinder could well be my next Bucket engine, after what, thirty odd years.

What is the plan to drive the disc?


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[husaberg]

Yes, that last version, translated with Deepl, does look more like the king's English; not bad at all.
In case you wish to compare it to the original text and at the same time brush up your German a bit:

Cheers everyday is a school day. But i struggle enough with English.

The CCR for a reed seems to be limited to about 1.3 - that gives enough volume for the pipe to draw from, and also allows petals thick enough not to go out of control.
But many larger displacement cylinders like a value slightly larger than this ie a smaller case.
.

In my search the other day i had seen a reference Frits had made ot the size of he reed valve Derbi case or the Rumi (i was skimming sorry)
Frits referenced it as being i think (if i recall correctly) as being quite a bit larger than the RSA.
i will have a look later an put it in. here...
looks like i asked the question ....

Would that not relate only to a disk valve? I have often seen it mentioned the optimum Crankcase volume would be smaller on a Crankcase reed. but i have never seen a definitive figure.
If you or Jan recalls what were the volumes on the Rumi and the Derbi reed valve. I realise that you may not have the figures available......but a a rough guide would be helpful

Frits Overmars esquire The Aprilia RSA125 has a TDC crankcase volume of 675 cc. That gives a primary compression ratio of 675 / (675 - 125) = 1,23. Rather different from your value....

I remember Jan saying that the crankcase volume of the Derbi reed valve engine was even larger than that of the rotary engine. And after Jan had laid his hands on it, that reed valve engine was the strongest 125 cc reed valver ever.
You see, the volumes of the transfer ducts and the volumes between the crank wheels and inside the piston are largely equal, and the volume of the reed cavity is a lot larger than the volume of a rotary inlet duct.

but your post and looking though an old collection of 1990s stuff i seen an old Boyseen 2 stage reeds packet (i had kept an it listed the reed number on the back for all sorts of bikes so you could cross reference )



i got me thinking did those old 2 stage reeds do anything and do they work in such a situation.
They were successful in separating my money from my wallet and the stickers impressing passers by....

did they work in the old days and could they wok on say a VFoorce set up as anyone tried them in a modern reed valve?

[Flettner]

What is the plan to drive the disc?


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Don't know yet. Initially I was looking at the twisted tooth belt system, but over Christmas I've had a massive clean up of my workshop and have found a nice little set of helical right angle gears. So maybe that with a drive gear running off the top of the clutch gear.

[flyonly]

Don't know yet. Initially I was looking at the twisted tooth belt system, but over Christmas I've had a massive clean up of my workshop and have found a nice little set of helical right angle gears. So maybe that with a drive gear running off the top of the clutch gear.

Have you decided on the diameter. I am interested in doing something similar but would need to be twisted belt


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[Flettner]

Have you decided on the diameter. I am interested in doing something similar but would need to be twisted belt


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I have a large disc, spare out of my 360cc engine, that Ill use. It is all going to fit into a TF Suzuki 125 engine (farmbike) , most probably have to cast a new case to accommodate this disc drive.

[Flettner]

140 dia, plus small angle drive, hardened teeth.
Disc still to be cut to the appropriate timing.

[lodgernz]

If I were to channel my inner "wobbly" and attempt to throw down a hand at 'long distance troubleshooting roullette'
My first question is, why so cold, Batman?
Targetting 470c with the pipe design???
That should be ~600c if you want to make real power.
Only achieving a derived (not directly measured with high speed EGT probe....) 340c?
Re-running the pipe design for 340c would NOT be my first advice.
I would first wonder why your pipe is so cold to begin with, assuming it truly is.
The most likely culprit from a general theory perspective would be the tailpipt outlet diameter. Often termed "D_restrictor" in some pipe formulas....
If you have the exact diameter in your pipe on the bike from the formula you used, and you are that far under the formulas target EGT, I would have questions about the engine actually meeting the input parameters that went into the pipe calculator, or the pipe calculator itself, is it the FOS formula?
You should be closer to 600c EGT for an incredibly general ideal.
Being cold either means you are not delivering the heat energy that the calculator assumes you would have been delivering to the pipe or the tailpipe diameter on your actual pipe is larger than the calculator actually spit out.
Taking the tailpipe restrictor diameter smaller WILL increase the pipes EGT, and if you are currently "too large", making it smaller WILL bring with it an increase in power up until the point where you go "too small" and you burn holes in your piston, so there is a balance point to be found, and the pipe formula wont give you the EXACT perfect number for your engine. It SHOULD give you a generally safe place to START, and you tune it from there.
Generally speaking shrinking the tailpipe diameter is going to increase the EGT.
Inreasing the EGT will increase the net temperature of the pipe.
Increasing the temperature of the pipe will make the speed of sound within it FASTER.
Faster speed of sound = faster wave travel.
Faster wave travel = pipes natural "resonant frequency" goes up.
Well look at that:
1. You pipe is too cold (not metting the formula number).
2. Your pipe is peaking at too low an RPM (resoanant frequency LOWER than formula number).
So, logic says:
Make the pipe hotter (decrease tailpipe restrictor diameter) and you will see an attendent increase in pipe resonant frequency, maybe even landing exactly where the formula said you would be once you actually achieve the 470c EGT you entered into the formula.

This pipe was the sixth I have made for this bike, and my temperature assumption for it was based on similar experiences with previous pipes.
The tailpipe de Laval nozzle ID in this pipe is 14.0mm. Frits's formula for the nozzle ID, based on a crank HP of 16, is 12.4mm. This seemed too small to me, but I agree that making it smaller than 14 is the first step.
I'll fit a 13.0mm nozzle and do some more dyno runs. I suspect that a higher EGT will show the Lt of this pipe to then be too short.

Wos has also suggested that EO 192⁰ is a bit conservative. Maybe I need to raise that a little as well.

Thank you both for your advice.

[wobbly]

LODGER - I see a few things that have set you off on a dead end tangent.
You say you used an EGT of 470* - this is completely erroneous.
Any engine with that number in the header is about as well tuned as a weed eater.

All of the pipe compute programs are using the BULK AVERAGE PIPE TEMP, including the cooler duct, and this is in the range of 550* to around 625* dependent upon the fuel quality.
This gives an average speed of sound of 560 to 610m/s, thus a pipe average wall temp of around 425*C to 450*C at peak, and the EGT as measured in the header well into the 600*'s.
Quit working in the dark, even after a ton of carrots, IMHO it is absolutely impossible to do any meaningful engine design work, let alone accurate track/dyno tuning without using a data logged or at the very least a max recall EGT gauge.

Also, if you are absolutely insistent on accelerated engine wear, and loosing Hp, carry on using Motul 800 @ 30:1, I wouldn't use that cats pee if it was free even @ 20:1 where you should be.

The Wobbly Duct info sheet also states a recommended cooled duct length @ 1.5 bore for a square engine, with the header entry @ 2X bore - you stated a cooled duct out to 2X bore, this is NFG
as the A/F out at 2X bore is never going to make it back into the cylinder due to the return wave, as the port is closing.

EDIT - again, taking a suggestion the 192* " is a bit conservative ". What the hell does that mean, what is the actual Blowdown STA, and what are the transfers doing. JanBros has a free , really good port calculator.
Quit working in the dark - free technology is at your fingertips.