ESE's works engine tuner

[Frits Overmars]

There are people in this world that uses an Excel spreadsheet and acoustic theory to create what they claim is a simulator that calculates what your exhaust pipe should look like.
They publish this mostly on Farcebook so I thought it would be a good idea to add another installment on gasdynamics.
Please give comments so I can improve this.

I am terribly sorry to have to say this, Neels, but your dissertation CAN'T be improved .
Well okay, one minor misspelling: "Typical pressure pulses in an engine has amplitudes..." should read '..HAVE amplitudes...".
Did you have one particular Fakebook contributor in mind (Michael Forrest) or are you dedicating your treatise to all the Dunning-Kruger cases over there?
https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

Neels, would you kindly allow me to share your Gasdynamics 101 ?

[Vannik]

Neels, would you kindly allow me to share your Gasdynamics 101 ?

Frits, please feel free to share wherever you like.
I might later fix the grammar error but not now.
And yes, you know exactly who it is aimed at.

[Condyn]

I have never seen somebody promote propaganda quite like “ he who must not be named “

[philou]

Facebook the worst time waster. everyone is an engineer, doctor, economist, tuning engine

the easier access to knowledge, the more people seek and choose the easiest even if it is false. which increases the spread of stupidity.

[OopsClunkThud]

Other than the impracticality of packaging, is there any reason the intake can't be placed on the exhaust side of the cylinder?

The thought came while working on the base of the transfer ports and I just kept looking at all that unused real estate below the exhaust.

[Condyn]

Arctic Cat ( Suzuki ) engines have case reeds on the exhaust side. They tilt way back in the chassis, giving them the nickname “ laydown “ engines.

[husaberg]

It's not your parallel-twin (it's the Dutch Rimar 600V2) but it might give you some pipe-fitting ideas.
Attachment 350439 Attachment 350440 Attachment 350441 Attachment 350442

Pretty sure fletner did a tornado chamber for one of the creations already
plus with 700cc he can give away a few HP

Whilst not as Shinny but very petite Mr Mike Green's earlier chamber. off the web


Scooters also use some lever tricks for packaging

[Tim Ey]

On behalf of the gearbox for the 700cc: It seems it was done before.
https://grabcad.com/library/gearbox-...lled-on-kart-1

Regarding the piping in a 700cc twin: you can always go the 2in1 way. Otherwise making the pipes thinner should not kill all the power if done proper.

And regarding packaging in the most complex ways, have a look at the vespa scene:
https://falk-r.de/
http://pipedesign.de/home.html

[Flettner]

I have managed this reverse pipe ok. Single cylinder 360cc, YZ 250X gearbox. Just double it up.

[husaberg]

https://www.cycleworld.com/2016/02/2...orld-classics/

Powering the Tul-Aris is a highly modified Polaris snowmobile engine. The two-stroke Twin has been enlarged to 780cc with hop-up components intended for snowmobile competition, though the straight-shot expansion chambers actually allow it to make more power than in a sled–165 crankshaft horsepower. The engine breathes through twin carburetors and reed valves at the front.

And smart enough to mount the water pump real low.

[TZ350]

Living the dream........ quitting regular work for a life of following his passion. I take my hat off to everyone who has done that.

[Flettner]

So I guess we make the 700 twin fit an R1 chassis, as we have one.
Im not a fan of bolting everything to the engine, as a stressed member.
Or for my own road bike, make my own frame, twin shock, more room for stuff to fit.

[Pursang]

...
Down the page from Tim's link to the Rotax gearbox
https://grabcad.com/library/gearbox-...lled-on-kart-1
was this pic of a pair of pipes neatly arranged on the side of the machine.



Obviously, for a motorcycle, you would need to put a saddle on top,

Cheers, Daryl.

[andreas]

So I guess we make the 700 twin fit an R1 chassis, as we have one.
Im not a fan of bolting everything to the engine, as a stressed member.
Or for my own road bike, make my own frame, twin shock, more room for stuff to fit.

Those are all good ideas, be interesting to follow either one.

[Javier Ruda]

There are people in this world that uses an Excel spreadsheet and acoustic theory to create what they claim is a simulator that calculates what your exhaust pipe should look like. They publish this mostly on Farcebook so I thought it would be a good idea to add another installment on gasdynamics. Please give comments so I can improve this.

Attachment 350438

Thank you Neels for sharing this knowledge, so far my understanding was “sound waves type” .

Now I am modifying a Rotax 122 cylinder, and I need to increase blowdown sta. For not increasing exhaust timing, my intention was to make the auxiliary ducts taller, but after reading the gas dynamics article now I think there is possibility of contributing to a shock wave that looses energy as heat.

For increasing peak power, Is there a rule of thumb for auxiliary vs. main exhaust port timing?