Transfer Port Theory

[Old Bob]

"frictional losses and boundary layer effects" is all you have? c'mon man, get real. prove to me in some kind of real example how I am wrong about the relation of transfer port widths to cylinder bore. It's just basic physics. It's the port area being a percentage of the bore area. Are you going to tell me that that is not important? You going to tell me that if a small and large engine both have accumulated widths the same percentage of the bore circumference, and that leaves the large engine with transfer areas as smaller percentage of the bore area that it don't matter? WTF? think, man, think. get out of the box (the limitation of what has already been written). Progress means building on top of the past, not being limited to it.
I have pointed out something that no one else has ever done and recorded for future generations to see and you are upset that it can't be possible that someone with so little study time under his belt could do so. Maybe you haven't seen my web site. Click on my signature link. I also have figured out completely about how expansion chambers work and how to accurately, using calculated return waves with an Excel file that took me months to make, analyze and design pipes. It's totally breakthrough. You gonna throw a fit about that to? Some people are forward thinkers and some people want to only defend the past. It's obvious which one you are.
The time-area idea for ports is obvious, again being basic physics, but the formula Jennings gave us from the Yamaha engineers was only accurate for the Grand Prix engines they were working with. If in your 30 years experience if you had ever played around with it you would know that and wouldn't now be throwing it at me as if you have some kind of valid point.
You keep telling me to read, but it don't seem like you know how, otherwise you'd know from what I've already wrote that I have read all that's available and then some. As an example, I brought the idea to this forum of intake extension for piston port intake engines, to increase low rpm power, from an obscure research paper I stumbled across. Crap, I bet you haven't read Blairs stuff. I barely made it through because everything he wrote was for engineers familiar with many complex formulas. You remind me of 2door, the dumbazz moderator on the other forum that had never even heard of using JBWeld in ports to modify them although famous 2 stroke gurus had been doing it for decades. 2door had lots of experience under his belt and thought he was at the pinnacle of knowledge whereas in reality he just knew a few things really well and had a very closed mind. Like I said, give me an argument with details. I'm waiting...

I'm not giving you anything, you don't know what you are doing or talking about and misleading the noobs that read your misguided theory.

There is no link in your signature.

Take a look at a 20-30cc modern 4 transfer port two stroke used in various applications such as gopeds. Shoots your theory down doesn't it?

 

[Deleted member 12676]

The link to my website is right there in plain sight.
All I'm saying is that ports are more efficient on smaller engines. The fact that certain small engines use 4 transfer ports is of little importance to this conversation because port area is only one factor. The advantage of doing so is to slow down the transfer velocity. The smaller the port, the higher the velocity for the same initial pressure. again, basic physics. Having a healthy crankcase compression ratio of close to 1.5:1 is advantageous for maximum drawing in of air/fuel charge. Smaller engines have less distance for the intake charge to travel to the spark plug and so need means to slow it down. Having larger transfer ports accomplishes that. But the designers of these chinese engines wanted minimum power and so utilized low CCR which allowed them to utilize the simplist design for transfer ports, that being just two. We can change the design for increased power by stuffing the crankcase for increased CCR and adding boost ports.

 

[Old Bob]

Nope don't see any link.

I'll say this again, you CAN NOT SIMPLY SCALE DOWN A LARGER DESIGN.

I can see why you aren't welcome on the other forum.

 

[Deleted member 12676]

yeah, you refer me to Jennings but his time-area formula shows that the port area is in relation to engine displacement, no matter what size engine.
please tell me, in detail, why I can't "scale down a larger design". The only reason I compared the two engines was to prove that ports on a small engine are more efficient.
Your attitude is very much in alignment with the Nazi controllers of the other forum. That's where you belong. This forum allows people to share new insights and viewpoints that have never been considered before. Any person of any intelligence knows that knowledge is an un-ending road that leads to many varied sights. To say that everything that can be known about 2 strokes has already been discovered is very narrow-minded and stifling.

 

[Deleted member 12676]

Although small engines can achieve a better port area to engine displacement ratio with the same percentage of bore circumference as a larger engine that doesn't necessarily mean small engines should be designed with small ports. There are other factors to consider, especially the CCR and the intended powerband.

 

[lazylightning@mail.r]

I'm not giving you anything, you don't know what you are doing or talking about and misleading the noobs that read your misguided theory.

There is no link in your signature.

Take a look at a 20-30cc modern 4 transfer port two stroke used in various applications such as gopeds. Shoots your theory down doesn't it?

Hi Bob,

Nice to meet you. Alot of us here are trying to learn how to make some improvements to our engines performance and this fellow Jaguar here has done alot for us. I didn't see the link to your page with tuning recommendations.
Though some of us may have some learning to do, I doubt anybody on this forum would like the word noob being thrown around in any ole direction it might happen to fly. I suppose that means any of us here without 30 years of experience in motor tuning. Noob is one of those words that would make one look younger than 50+ though, so I suppose it's tempting to use it, even if having not learned any good manners when coming to tech chat with some strangers. Or maybe your really younger than you present yourself.
Actually here's the link to Jaguar's page: http://www.dragonfly75.com/motorbike/index.html There's alot of really useful information there and it's a darn shame you haven't taken into account all the hard work he's put into it to help us out here.
Presenting a theory after all, is just a theory. He didn't claim to be absolutely correct and has shown himself as reconsidering previous ideas when evidence shows otherwise. Now I think that he's being open minded and ready to accept scientific facts as he finds them.
It seems to me your statement deeming his theory incorrect was not built on an argument. You just stated it and accused him of misinforming us. Wow! How about some formulas?
So these little engines usually do only 5000 - 6000 rpm's at most. If they have had bearings changed, balance work done, carb, pipe and basically everything, then maybe you'll get 8000. It might blow at 9000 though. So, it seems that velocity isn't that much of an issue with these. If it were a Franco or Peugeot 103 or something, then maybe so.
Please be kind enough to build your theory or case in more detail. It is beneficial to us all.
And I can't understand your need for rudeness. This guy is proven as a good guy. Why just go around offending people. Please build your argument with intention to show him the error of his ways instead of coming off so high and mighty over all the noobs and anybody trying to explain their theories.
Please don't take offense, it's just very important to keep an atmosphere of good manners and friendliness here.
Again, it's very nice to meet you. Please feel free to contribute to our collective knowledge of maxing the low rpm HP out of these little teaser engines ;-)

Cheers,
Paul

 

[Fabian]

@ Old Bob

One thing is for sure. Jaguar has brought forth a needed product to the market place, being his 2-stroke CDI for Chinese 2-stroke bicycle engines, and that can't be taken away from him.

Old Bob, I would like to see you make a youtube video demonstrating and refuting Jaguars theories using your flow bench and the data that comes out of it, also setting up a few different cylinder and crankcase combinations and running them on the dyno to prove things one way or the other.

The old saying: the bull-s.h.i.t stops when the dyno rocks, but what we really need is a video to prove it.

 

[Fabian]

Oh yes, i have also been banned from the other forum, as have many others at the hand of that dipstick moderator 2-door

 

[Old Bob]

If there were valid engineering principles being discussed my attitude would different.

This guy is proven as a good guy.

Thats why hes banned for life from the other forum?

Actually here's the link to Jaguar's page: http://www.dragonfly75.com/motorbike/index.html There's alot of really useful information there and it's a darn shame you haven't taken into account all the hard work he's put into it to help us out here.

Can you say plagerism? anyone can cut and paste...



http://www.dragonfly75.com/motorbike/forums.html

This is the garbage that he posts about people who disagree with him.

 

[Fabian]

I am not only banned for life on the other forum, but for a further 3 reincarnations of my future lives. 2-door had a hissy fit when i advocated 25:1 oil/fuel ratio in relation to the low quality castings of the Chinese bicycle engine, when used at high duty cycle in a low airflow environment.
I cited extensive research from Suzuki Corporation back in the 1970's when they were experimenting with leaner oil/fuel ratios and the associated piston scuffing at anything over 35:1

2-door couldn't accept that research and i was banned for not just one life, but many future lives.
Ok, it didn't help my cause when he advocated opti-2 oil at 100:1, and i called him a d.i.c.k-head for giving out such advise.

So, does that mean i am also qualified to be a f*&kwit because i'm banned on the other forum?