ESE's works engine tuner

[jbiplane]

Here are a few more pictures showing the velocities in the exhaust. It should give a picture but i keep in mind that I have been told that the calculation grid (mesh) still could do with some refinements and more refinements still. I have also been told (yes I tried to push a little) that doing a fully dynamic cycle, possibly with combustion and everything is quite complicated and I think we would have needed more 2-stroke knowledge. Unfortunately, we have to work with others things during working hours for a while now...

Hi Norman

Could you recommend any available in internet consistent sources to perform CDF analysis of 2-stroke engines in Fluent.
I saw only one tutorial consistent for scavenging efeciency in Fluent.
https://www.mr-cfd.com/two-stroke-engine-scavenging/
and PhD Thesis
https://www.google.ru/url?sa=t&rct=j...1lbH6ebGMaFFa-

Valery

[Frits Overmars]

That is a lot of good reading. Thanks Valery.

[Norman]

Hi Norman

Could you recommend any available in internet consistent sources to perform CDF analysis of 2-stroke engines in Fluent.
I saw only one tutorial consistent for scavenging efeciency in Fluent.
https://www.mr-cfd.com/two-stroke-engine-scavenging/
and PhD Thesis
https://www.google.ru/url?sa=t&rct=j...1lbH6ebGMaFFa-

Valery

Thank you for the interesting information. I earlier got some assistance to make a series of simulations to better understand the airflow paths through a "RSW type" engine (cause I find in general somewhat difficult to fully understand the (dynamical) flow through a two stroke). I would have liked to make them dynamical with a full piston movement, but the circumstances at the time did not allow this. I have a quite new contact with a Ph.D. in CFD calculations. I will discuss this topic with him to see if I there is a possibility to continue somehow. It also depends on the time he is willing to give me on this, because to buy in these kind of simulations is very expensive, you will hardly get a calculation start up under 5000EUR. I cannot give any time schedule on this. However, if and when, I find out something that could be to some use for anyone here, I will share. At the moment I do not know any better source than you presented Valery, I'm afraid.

[Magnus676]

Hi there guys,
I have a question regarding port timings.Most say thats a matter of rpm,but I think its a matter of piston speed.Let me explain my thinking:
Lets say we have 2 engines that both give max power at 10000rpm.The one is a 50cc engine and the other say a KTM 300.Theoritically they both should have the same exhaust timing,lets say its about 192 degrees.But,the way I'm thinking this is wrong because it doen't take into account how fast the piston moving,it takes just how fast the crank is spinning.I know we cannot accurately say at what speed the piston opens and closes the ports,but here are some numbers if we take into account mean piston speed:Lets say the 50cc engine is square just like the KTM,so it'll have a 40mm stroke wich gives us a mps of 13.3 m/s.Thr KTM on the other hand will have a mps of 24 m/s,so the piston will open and close the ports in a greater speed.
So my damn head thinks that if the piston opens and closes the ports faster then we have to give the ports more duration,although the rpm is the same with the 50cc.
This theory of mine may be trash,so I want to hear some opinions from you guys and learn something today
Edit:If forgot to mention.With this theory an oversquare engine will need less timing for the same revs than a square at the same displacement.But I think that doesn't apply her because you need more port area than a square engine to make the same power as mentioned before.

[RomeuPT]

Hi there guys,
I have a question regarding port timings.Most say thats a matter of rpm,but I think its a matter of piston speed.Let me explain my thinking:
Lets say we have 2 engines that both give max power at 10000rpm.The one is a 50cc engine and the other say a KTM 300.Theoritically they both should have the same exhaust timing,lets say its about 192 degrees.But,the way I'm thinking this is wrong because it doen't take into account how fast the piston moving,it takes just how fast the crank is spinning.I know we cannot accurately say at what speed the piston opens and closes the ports,but here are some numbers if we take into account mean piston speed:Lets say the 50cc engine is square just like the KTM,so it'll have a 40mm stroke wich gives us a mps of 13.3 m/s.Thr KTM on the other hand will have a mps of 24 m/s,so the piston will open and close the ports in a greater speed.
So my damn head thinks that if the piston opens and closes the ports faster then we have to give the ports more duration,although the rpm is the same with the 50cc.
This theory of mine may be trash,so I want to hear some opinions from you guys and learn something today
Edit:If forgot to mention.With this theory an oversquare engine will need less timing for the same revs than a square at the same displacement.But I think that doesn't apply her because you need more port area than a square engine to make the same power as mentioned before.

I think the scale of things is important, example: big engines tend to have high pre comp but have to use lower head comp to work.
Difference in pressure make the gases move from place A to B, but the speed of moving does not have a linear correlation with pressure differences, bigger displacement has longer ducts etc, it takes more time to do the same gas dynamics at the "phisical scale" of a two stroke. In short... gases moving at around the same speed will have much more trouble to scavenging a 72mm bore then a 40mm if they have the same time.

[peewee]

well today didn't go so good. I think the 15% nitro by volume was really more like 25% by weight , based off some conversion charts. the difference between volume and weight at the 40F fuel temp made for a hotter mix than I expected. ive included these charts in case anyone wants them for their own reference, they can be handy if no hydrometer is available. anyways I richened the needle as much as I dared, alittle to far in fact. it popped out of the emulsion tube and the slide stuck open which caused a brief moment of panic until I was able to press the rear brake and kill the engine. ill have lectron send another needle and ill try again another day. heres a short crappy video but you can hear its pretty lean when I rev it and the slide closes, it has that zingy sound. sure goes like hell at full throttle though

[TZ350]

Hi there guys, I have a question regarding port timings. Most say that is a matter of rpm,but I think its a matter of piston speed. I want to hear some opinions from you guys and learn something today

STA (specific time area). It takes into account the things you mention.

A Google search of this thread will bring up plenty of discussion about STA for you to check out and compare ideas.

Use Google to search this site, use an ordinary search phrase and after it add:- site:www.kiwibiker.co.nz

for example

Frits priceless site:www.kiwibiker.co.nz
or
Frits pisa site:www.kiwibiker.co.nz

Mick

[F5 Dave]

Hey Peewee nice day out there for Autumn out your way .

[adegnes]

well today didn't go so good. I think the 15% nitro by volume was really more like 25% by weight , based off some conversion charts. the difference between volume and weight at the 40F fuel temp made for a hotter mix than I expected. ive included these charts in case anyone wants them for their own reference, they can be handy if no hydrometer is available. anyways I richened the needle as much as I dared, alittle to far in fact. it popped out of the emulsion tube and the slide stuck open which caused a brief moment of panic until I was able to press the rear brake and kill the engine. ill have lectron send another needle and ill try again another day. heres a short crappy video but you can hear its pretty lean when I rev it and the slide closes, it has that zingy sound. sure goes like hell at full throttle though

Great that you're doing the nitro thing! I'm out of business for a while until my engine is back together. Until then I can follow your progress.

[jasonu]

Don't undervalue the engine so much, sometimes new techonology promises but needs time to grow before it makes a worthy difference. example: graphene

Not under valuing the engine, just all the shit that those involved spouted.

[peewee]

Great that you're doing the nitro thing! I'm out of business for a while until my engine is back together. Until then I can follow your progress.

i dont know if you could call it progress. more like throwing mud at the wall and hope something sticks . but i think ive got the full throttle sorted out. now its just a matter of keeping it rich enough when the slide is closed. one other odd thing ive noticed recently, when idling if the throttle is opened, sometimes it will bog and kill the engine. im not sure if its from being to lean or the engine isnt warming up enough. anyways i dont think i have any spare bits that would be of any value to you (most of my spares are for dirtbikes) but i could help out if youve got a contribution page or something like that

[adegnes]

i dont know if you could call it progress. more like throwing mud at the wall and hope something sticks . but i think ive got the full throttle sorted out. now its just a matter of keeping it rich enough when the slide is closed. one other odd thing ive noticed recently, when idling if the throttle is opened, sometimes it will bog and kill the engine. im not sure if its from being to lean or the engine isnt warming up enough. anyways i dont think i have any spare bits that would be of any value to you (most of my spares are for dirtbikes) but i could help out if youve got a contribution page or something like that

😂
That's interesting, I've experienced the same bogging. It goes away if I apply the choke, but the weird thing is with the choke on it acts leaner and idles high. Maybe the fuel part of the pwk choke circuit needs drilling too.

I'm very thankful for all the help I can get! But I don't want anyone to feel they have to. I'm very thankful for you guys watching my videos and contributing with advice and help too!

I've got a Patreon account:
https://www.patreon.com/2strokestuffing

If you don't want to do the monthly Patreon deal you can donate directly via this PayPal link:
https://www.paypal.com/cgi-bin/websc...=BMXLUFKASKAJC

I've started porting the cylinder, can't wait to see how it behaves!

[peewee]

😂
That's interesting, I've experienced the same bogging. It goes away if I apply the choke, but the weird thing is with the choke on it acts leaner and idles high. Maybe the fuel part of the pwk choke circuit needs drilling too.

I'm very thankful for all the help I can get! But I don't want anyone to feel they have to. I'm very thankful for you guys watching my videos and contributing with advice and help too!

I've got a Patreon account:
https://www.patreon.com/2strokestuffing

If you don't want to do the monthly Patreon deal you can donate directly via this PayPal link:
https://www.paypal.com/cgi-bin/websc...=BMXLUFKASKAJC

I've started porting the cylinder, can't wait to see how it behaves!

hey mate ill send some help your way. if you can get it sorted out,it will likely help me. like i said, i havent a clue what im doing with nitro. ive no idea where the spark lead needs to be, what com ratio i should have, what oil ratio is best, where the cylinder temp should be. thats why i describe it as throwing mud at the wall. i suppose if it doesnt seize or blow up then i must be going in some what of the right direction

[marsheng]

OT I'm going from Chch to Manfeild this weekend 26-29 October and have space in the closed trailer for one bike either way. If you need a bike moved, please contact me asap. marshland@marshland.co.nz.

Cheers Wallace.

[adegnes]

hey mate ill send some help your way. if you can get it sorted out,it will likely help me. like i said, i havent a clue what im doing with nitro. ive no idea where the spark lead needs to be, what com ratio i should have, what oil ratio is best, where the cylinder temp should be. thats why i describe it as throwing mud at the wall. i suppose if it doesnt seize or blow up then i must be going in some what of the right direction

Thanks, means a lot!
Sounds like we're in the same boat concerning nitro...