ESE's works engine tuner

[TZ350]

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Outer rotary valve cover and ignition trigger.

[PVO]

I did a lot of crankshaft speculation for a low mass aircraft engine and a pressed up crank is not low mass.

[URL="https://www.homebuiltairplanes.com/forums/threads/side-valved-two-strokes-for-angels.32119/"]

If You are interested and give me some dimensions I will love to try some alternatives for mass calculation and I know how to balance a V2.

Thanks for your offer, I will keep it in mind as the design progresses. I'm not far enough along to provide any solid design parameters.

The big issue in my opinion for a single piece crankshaft for this type of two stroke is the split cage big end bearings and need to assemble the conrod perfectly to ensure the bearings last. The fracture method is preferred by Rotax but those rods aren't sold without being assembled to the crank and it is unlikely I'll be able to replicate their process.

[PVO]

PVO it seems rods on large bore snowmobile applications are always too short. I think it is because the deck height has constraints to fit in todays tightly packaged chassis.

I have not been following your planning closely, are you wishing to sleeve down the cylinders and increase stroke length to square? I could be wrong, but my gut instinct would tell me In order to achieve a 2:1 r/s ratio with the longer stroke the case volume would rise dramatically, unless you are planning to add to the topside of the cylinder which ends up being a lot of work.
How long are the factory 850 rods?

I agree, the rod length manufacturers are selecting has a lot to do with packaging. For me, since I'm designing the package I think I'd prefer to get good rod length, case volume, and reduce thrust loading first and then work the packaging second. I like to design in parallel so I can iterate on both as needed.

Arctic Cat is the only manufacturer with an engine design that has the cylinders made individually in the 800-850cc class. Everyone else uses a mono block cylinder so they won't work.

My plan is to design and cast the cylinders for my engine. They are the heart of a two stroke so compromising on the cylinder is a false step to take early on in my opinion. I've designed two stroke cylinders for others based on the design principles shared by Frits, Jan, Wobbly, Vannik, and others and have achieved good results so I don't feel like this is an overwhelming task and I quite look forward to it.

I don't know the 850 rod length but wish I did to establish a starting point. As I've mentioned to others you cannot purchase 850 rods without buying the crank assembly.

[PVO]

Hot rods and others sell the bits you need
Making rods as small runs is quite expensive.

http://www.transcanimports.com/downl...ing%20Rods.pdf
https://www.pro-x.com/prox-connectin...ensions-brand/
https://www.wandamotor.com/connectin...2253_2540.html
https://www.kimpex.com/en-ca/product...onnecting-rods
https://www.mitaka.co.uk/MDP.htm
http://catalog.vesrah.co.jp/list/product_parts.asp
http://www.samarin.nl/webshop/index....ewCat&catId=32
https://www.tkrj.co.jp/product/m-con...g-rod-kit.html
https://www.twsgb.co.uk/hot-rods-con-rods-37-c.asp
http://http://www.samarin.net/?productos
http://www.pvlsverige.se/vrm/index/index22.html

Polaris 700 and 900
C-C 152.1 mm
SE od 27mm
BE od 40mm
SE Width 20mm
BE Width 20mm
SE bearing 22 x 27 x 25 mm

Thank you for these references - more stuff to look through and consider!

[TZ350]

2Stroke Stuffing is getting somewhere. He is now nipping at the heals of the best conventional Dutch racing 50cc engines.

[Muhr]

My guess is that 1280*F was seen in the header near the cylinder. I was planning on following these layouts where the Turbo is attached at the stinger. If it is still to hot there I will attach the Turbo to the mid section, where I expect the exhaust gas is at its coolest.

Glad to see you embark on such a project! Will be interesting to follow.
You gave me motivation to continue my project that has been going on for ages.

[Flettner]

Wobbly, who was the company you deal with to get your dyno load cells and associated softwear?

[ken seeber]

Wobbly, who was the company you deal with to get your dyno load cells and associated softwear?

"Dominik
All Aliexpress. From memory the cells were about $30 and the displays maybe $50 I think. Brett can confirm
Today at 4:19 PM
4:19 PM

Brett
Yep'

[Muhr]

2Stroke Stuffing is getting somewhere. He is now nipping at the heals of the best conventional Dutch racing 50cc engines.

Does not want to be negative but looked like he was doing a negative RPM pull? which should mean that the power reading is a combination of engine power and and braking power?(If he brakes harder he can have 100hp)

[SwePatrick]

Does not want to be negative but looked like he was doing a negative RPM pull? which should mean that the power reading is a combination of engine power and and braking power?(If he brakes harder he can have 100hp)

The software is smarter than that
It measures the amount of power it takes to pull down the engine at a certain rpm per second.
And if breaking it harder it knows the power because the rpm goes down faster.

Totally normal.

[Muhr]

The software is smarter than that
It measures the amount of power it takes to pull down the engine at a certain rpm per second.
And if breaking it harder it knows the power because the rpm goes down faster.

Totally normal.

Ok so he has a load cell also on the magnetic brake to equalize the braking force the rotating mass?
Thought the bench was much simpler composition.

[wobbly]

Flett - I have used SportDevices software and their SP1 dyno data pack for over 15 years - the basic data box can do inertia or load cell or both.
After testing everything from Superflow to DynoMite etc , this is by far the easyest to use.
And it has two K type temp inputs on the front I use for egt and water temp.
All the inputs are configurable for stuff like Lambda , fan control etc.
The software is super easy to use , and I have the option of a Hall Effect sensor that reads the 126 teeth on the starter flywheel ( a small Toyota auto flex plate ) that is geared 1:1 to the flywheel.
I have asked them for many upgrades to the software ( free download ) and they do them very quickly.

The latest software versions specifically for Windoze 10 you have to be careful to download a driver to suit the old ( very ) serial port - RS232 that the box uses.
This really is the correct data system for reliable transfer in any noisy industrial applications , but of course nowdays no laptops or desktops have serial anymore
so you need to use an adapter.
Sportsdevices can give you a cable ( oddball ) that has the Serial to USB adapter on the computer end ie the cable is actually Serial wires , this works perfectly.
But maybe the latest version has usb as a default , dunno.

The only thing I would insist on , that many ignore , is to get a one way clutch , as is sold for tractor pto drives for mowers etc.
Then if an engine locks up , the dyno inertia wont keep driving the crank around to complete its destruction.

[Flettner]

Thankyou Wobbly, Ken, Brett

[porttiming124]

Good morning all . I am currently working on an engine that has two rings and I am looking for a piston with only 1 ring that I cannot find. If I remove the bottom ring is that the groove will serve as a bypass between the transfer and the exaust. I think the groove is so small that maybe it doesn't show. what do you think about it? thank you.

[Frits Overmars]

I am currently working on an engine that has two rings and I am looking for a piston with only 1 ring that I cannot find. If I remove the bottom ring is that the groove will serve as a bypass between the transfer and the exhaust. I think the groove is so small that maybe it doesn't show. what do you think about it? thank you.

The groove will indeed constitute a bypass. Whether it will actually serve as a bypass, depends on the exhaust and transfer pressures.
As you say, the effect may be small. Just try it; you've got nothing to lose.