ESE's works engine tuner

[Frits Overmars]

If you like triple or twincylinder sound...
https://www.simsonforum.net/download...1424&mode=view
https://www.simsonforum.net/download...1422&mode=view
https://www.simsonforum.net/download...1423&mode=view
https://www.simsonforum.net/download...1427&mode=view
https://www.simsonforum.net/download/file.php?id=31428&mode=view
Hope you like the sound.

I did like the sound Hoebra, but I could not see anything on those simsonform.net links.

Du hast keine ausreichende Berechtigung, um die Dateianhänge dieses Beitrags anzusehen.

I would be grateful if you could show your pics right here.

[Hoebra]

I tried this before but failed, I think now they should be visible?

[Hoebra]

two more pictures.

[wobbly]

Husa its well known that the YZ125 transfer flow is above supersonic , NASA has had this in their Mars lander for years ,so sharp septums ar de rigueur in this case.

[Frits Overmars]

I tried this before but failed, I think now they should be visible?

Yep, thanks. Interesting pictures

[DoldGuy]

Husa its well known that the YZ125 transfer flow is above supersonic , NASA has had this in their Mars lander for years ,so sharp septums ar de rigueur in this case.

Wobbly, I’ll be the one with the dummy questions as I didn’t know, what effect does this have on the divider/septum? And can you offer a simplified understanding of the intake resonance/ frequency and the need of different lengths of intake tracts?
Thanks in Advance.

DoldGuy

[wobbly]

The septum is there really only as the A/B port duct walls are differing radial angles , and having a knife edged entry to both these ducts creates eddies or turbulemce that can only disturb the flow
regime.The Aprilla septum was about 10mm wide on the outer wall ( a flat ) with radius edges into both ducts , as the wall angles were very different.

Re intake tuning. The two scenarios we are interested in are RV and reed.
The RV intake has to be made as short as is physically possible , this takes precedence over any sonic tuning , in that we have the issue of resonant waves bouncing off atmosphere - firstly as a closed ended
tube when the RV is shut , then in helmholtz resonance with the case .This can cause the same air/fuel mixture to pass the emulsion tube/needle up to 3 times, in and outward.
Creating havoc with trying to get a useable tune.

In a reed we have a completely different scenario.
Intake tuning in this case is easily seen to be working in EngMod . We have the case gradually going into a negative pressure ratio around BDC due to the pipe and then the piston starting to rise.
As well as this we also have the intake tract seeing a cyclic wave travel up and down its length , from just past the bellmouth , and to ,on average about 2/3 of the reed port length ( as this varies as the petals lift ).

If you tune this intake length to give a 3rd harmonic positive pressure ratio arriving at the reeds , at the same time as the case goes negative , around the rpm you want , this pulls the petals off the ports as fast as is possible.
This + and - pressure ratio point slowly moves away from around BDC as rpm rises , and the result is that the reeds are giving usefull flow into the case at around TPC , much earlyer than would be the case without both
elements working together.

Here is a running EngMod file showing the case going negative at the same time as the intake goes positive , in this engine @ 10,000 rpm

This tuning makes a mockery of what we see on MX bikes , where due to room constraints , the exact same intake length of reed/manifold rubber/carb are used on a 125 as well as a 250.
How can the intake tune be correct for both - it isnt.

[husaberg]

Wobbly, I’ll be the one with the dummy questions as I didn’t know, what effect does this have on the divider/septum?

DoldGuy

What never ceases to amaze me is the inner curvature of the Honda transfer ducts. Even in their most recent race engines it was only 12 mm at its tightest point,
compared to a constant 22,6 mm radius for the Aprilia's inner curvature - that's almost twice as big, which makes a big difference in flow attachment.
Attachment 336552

[speedpro]

So, with a couple of Ø40 bearings and a Commodore front disc and caliper and some bits in between, the thing is now sort of in place.
Being a friction brake, I hope we can control the thing, manually, such that we can hold it at constant speed points, enough to optimise the mixture (which could be anywhere at present) and get a torque reading. If we used an inertia dyno it’d take years to get a decent clean carburation operation over the rpm range.

I built a similar setup with the brake for my fuel injected bike as I too needed to hold a load at set revs to see what the fueling was doing. In my case I used a roller and frame and mounted the bike to it. It wasn't too hard to hold the revs at set points with a long handle operating the brake. You will have problems where the engine is coming on pipe and power is increasing quickly. A little too much brake will drop it off power and too little will have the engine screaming. A bit of practice will help. I found it easier to have the engine rev over the rpm you were interested in and to pull it down with the brake. One person doing both brake and throttle although once you sort it out it works with 2 people as well. Data logging is a big help. Disc and caliper both retrieved from the scrap bin of the vehicle compliance centre.

[Frits Overmars]

Here is the simple version, for on-site minibike tuning at the track. The drum has enough inertia so it can also be used as an acceleration dyno. The small brake disk and caliper have their limitations however; long runs would quickly overheat them.


When we first used a disk brake for power measuring (in 1972 I think it was), we had the disk run partly submerged in a water basin. That solved both the thermal problem and the dust problem in our dyno shed .

[TZ350]

When we first used a disk brake for power measuring (in 1972 I think it was), we had the disk run partly submerged in a water basin. That solved both the thermal problem and the dust problem in our dyno shed .

Water basin for cooling the disk and dust suppression. Great idea. Thanks.

[Larry Wiechman]

I've used a machinist's coolant spray mister to cool a vented truck rotor. Aim the spray inside the rotor so the coolant exits through the interior vents and does not affect the friction coefficient of the brake pads. Properly adjusted, there is no mess. https://www.amazon.com/Coolant-Lubri...64684955&psc=1

[jfn2]

Wobbly or Frits
Sometime a while back one of you guys were talking about getting more HP by running a lower compression ratio. I came across a setup that runs very good and uses lower compression. I was wondering what parameters' you would want to change to run a lower compression engine? Say from a 180-200 psi cranking pressure to 130-145 psi pressure. This is in a 350cc TZ (old school engine). Thank you.

[Frits Overmars]

Wobbly or Frits
Sometime a while back one of you guys were talking about getting more HP by running a lower compression ratio. I came across a setup that runs very good and uses lower compression. I was wondering what parameters' you would want to change to run a lower compression engine? Say from a 180-200 psi cranking pressure to 130-145 psi pressure. This is in a 350cc TZ (old school engine). Thank you.

In principle I do not want to have anything to do with cranking pressures. The only thing they're good for, is a comparison between what your partical engine had before, and what it has now. If it's become worse, your piston ring, or the sealing between the ring and its groove, may have reached the end of their useful life.
I hear rumours about engines with inlet and exhaust valves, the so-called foul-strokes, and cranking pressure measuring may have its uses in such cases, but let's not go there.
And while we're at it, I don't want anything to do with so-called effective compression ratios either.

The idea behind more power from a lower compression ratio is, that the lower compression ratio before TDC equals a lower expansion ratio after TDC, which leaves more energy in the combustion gases by the time they enter the exhaust pipe. If that pipe is really effective, you may see your power gain. If the pipe is not, don't bother. And I'm pretty sure that Wobbly will feel the same about it.

[wobbly]

I agree with Frits , part of a power gain to be had resides in how efficient the pipe is - and in the TZ350 case the pipe is not.
But of more importance is the relationship between ignition advance and compression.
There is a fairly narrow range for both , and max power available from whatever combination is totally dependant upon the fuel.
The optimum for leaded race fuel is tipped heavily toward high compression , minimum advance , and lean as hell to get heat in the pipe without deto.
Unleaded fuels are the opposite , lower compression , more advance and a richer mixture are the direction that gives best power , again just short of deto.

So , just concentrating on compression is a mistake - there will be gains to be found by varying the ignition advance.
But as always , no free lunch , as you wind in advance , you will be reducing the energy transferred to the pipe , so its a balancing act to get the overev rpm and a higher power level, thats dictated by the fuel characteristcs.
And unless you have a modern ignition , the old factory setup only allows static to be wound in , and this automatically restricts overev.

The TZ350 has a modest BMEP ( partially due to the pipe limitation ) so the dynamic compression is not that flash. Thus for the fuel being used , more power is to be had by having a higher static compression.
Also in this case , having a lower compression , that will allow more pipe heat energy and thus more overev , will be of limited value , as overving the TZ with porting/pipe that simply wont support high rpm power will end
up reducing the mid , more than it gains up top.