afm

Ok guys, with respect to Crankcase volume, this is what I found:

The ideal crankcase volume has to do with the compresion in it, giving that way the necessary force to the movement of mixture through the transfer passages and ports and into the combustion chamber. It also has impact on the aspiration of new mixture charge because it affects the suction and speed in the induction passage. Of course it is related to carburator size.

Alfonso

EdwardN

iTrader: (1)

Hey BK. Yes you miss a lot by don't visiting forum lately.
I am really aplause to Alfonso and Reiner for their ammesing research work. I can tell you that now they have more info on hands and they know how to manipulate with this info better then many people who claiming that they know engines (no names listed).
As far as dummy piston-yes I agree with you. It is more accurate, but in the mean time for regular guy who doesn't have chance to drill holle on evey single piston it will be slightly dificult.
Alfonso, you have discovered one more very important thing in engines performance-crankcase volume. This is the reason I have pointed you to that direction-I knew you will get there to the end. So know you have to look for more info on it.
Next project is ports angles and area on sleeve. I am sure you will discover more there too. I was looking on internet and quickly found this http://macdizzy.com/cylinder_map6.htm. So for the beggining it should help. The rest guys it is chalange to get to the bottom of it.

mugenb46

iTrader: (4)

thanks for that info ed this stuff is frekin awsome, i love learning this type of info, it's very help to further understand this stuff, i'm having a blast with this thread, Cali is starting to sound good to me, and some beer

afm

Thanks ED

As a matter of fact I just happened to visit my parents home, and talking to my old man (still around luckily) about this project, he said he had a box with lots of notebooks that I left behind some 20 years ago....to my surprise I found a very important notebook of my Karting days which I thought lost, and in it had very valuable information on 2 strokes from my interviews with Naitob % Nomura from Yamaha, Roland Marechal from Rotax, Heine and Finn from Dino, Koene from Rotax, etc. etc. which in may days were the Top designers and tuners for world championship kart engines (late 80's early 90's)

I'm having a blast reviewing all the concepts written there, and I found lots of information that perfectly applies to our present hobby...

This thread is making me feel young again and I'm enjoying every minute.

Thanks again for youir kind words, and for supporting us and giving us leads and valuable information.

I'm sure Brian will jump in and trow us some valuable info too...

Alfonso

mugenb46

iTrader: (4)

Hey guys, i went to the macdizzy site and reveiwed the info on there and could not understand the statments made about port size, and serface area.. i'm guessing that the hight of the port when the piston is at BDC has something to do with the tourque VS RPM when it is shorter or taller. i see some sleeves with a fairley narrow fuel inlet port on the sleeve and then some are a little taller, is this what port toming is or just the diff between bottom power and top.

EdwardN

iTrader: (1)

Hello Alfonso.
Actauly I really thanksfull to you and Reiner. I have try many times here in forum find someone who is really interested in our engines, but always was end up by "how to polish ports". Every my attempt end up the same. Now it is really different story-first of all you guys really wanted to understand engines and all parameters which regulate engine perfomance, secondble you do all reasearch work by yourself and just need help on pointing what to look for. I really enjoy it.
Let's keep going this way and after couple of weeks a lot more people will understand how motor works, how to make modding etc.
Next step is ports volume. I am trying now find some info on the web, but so far couldn't find anything yet. Pretty much sure I will.
Alfonco please prepare your self to discover metalurgy principals for piston/ sleeve and crancase-that one will be really hard, but it is important as everything else in engines , don't go there yet, Let's finish with porting.
MugenB46-the height of the ports is dictating time of one or other event (induction, transfer, exhaust). In sertain combination it is dictating power band of of engine. Timing is really dictating where power band will be located (do not discard the rest of the varibles like pipe lenght etc).
Look here is pretty good explanation how our 2 strockers work in general it should help you to understand http://www.vf750fd.com/blurbs/stroke.html

mugenb46

iTrader: (4)

this stuff, i love it. ED ok so the bottom line is as far as tourque VS Rpm is that a shorter pipe creates a faster return of the exaust preasure back to the cylender creating more bottom end compared to a longer pipe slowing down this reaction giving more top power. am i correct? and then crank case valuem, can you have to little or do you want as much as possible. i would think that the more volume you have the more case preasure you would have or maybe it is just the opposite. i guess i want to know what more cas volume or less volume ='s or what is the benefit of having more or less.

nitrodude

iTrader: (8)

I cant anaswer your question, but the way I understand pressure and volume in general terms, is that the more volume you have of something the less pressure. Think of it as a waterhose, if you use a bigger hose, the pressure at which the water comes out is going to be lower, thats why we tend to pinch the hose on the end, to get more pressure.

Im paying attention to everything going on on this tread and Im loving it, keep it going guys.

EdwardN

iTrader: (1)

Actualy shorter pipe is for higher RPM and longer is for lower RPM. Tuned pipe is using resonance effect, when friquency of piston equal to friquency of returned wave in tuned pipe. So when 2 friquences are match each other, then resonance effect happened which we can call charging (actual work of tuned pipe).
Let's get to the sample-if your engine at one point running at 30000 RPM (500 Hz) and tuned lenght of your pipe is 155 mm long (tuned to 533 Hz or 32000 RPM), then when wave will come back to cilinder it will find exhaust port close so it will not make charge then pipe will not work as it should. But ones engine reach 32000 RPM and return wave will come to the exhaust port and find it's open then it will charge the combustion chamber and it will give you boost of up to 30% power and RPM.
Please go to http://www.prestwich.ndirect.co.uk/tunedpipetheory2.htm
it is very good english expalne how the pipe work with all basic formulas (I am not sure if my english is enough to understand what I try to explane-sorry if it was dificult).
About case volume-this is pretty complecated thing. Pretty much smaller case volume give you more internal pressure, but it is limited volume of mixture go through crancase. For engines with very wide power band and highely restricted carb-case volume needs to be smaller. For engines with narrower power band and working on higher RPM and pretty short power band case needs to be bigger-it is all general concept and in every case stady it is different-I personaly learned this hard way.

EdwardN

iTrader: (1)

I found this video on the web-you can easy hear when tuned pipe kick in. http://bob.marle.free.fr/prod02.htm
BTW I mesure RPMs on all 3 videos and found that Paul Eisner engine was running 38000 RPM, Alex Osovik 39800 RPM and Luis Paramon 40200 RPM. Paul Eisner broke the world record, but to brake world record is allow to use nitro and can use control line stabilazers. On the competions no nitro and no stabilazers.

DaRollaRacer

As far as measuring crankcase volume is concerned, why not fill it with water, then dump whatever water filled the crankcase into a small container (would a photo film case be too small?) and measure the volume.

Dave

mxwrench

iTrader: (1)

Guys, I did some digging on my hard drive and found the absolute best piece of reading material for you to wrap your brains around. It is Gordon Jennings 2 stroke tuners handbook. This book has been out of print for some time, but I managed to get a decent scan of it some time ago. I have posted the PDF file to my website for your viewing pleasure. I recommend saving the file to your hard drive and printing each page and making your own book out of it. This is a must have for any serious 2 stroke engine builder/designer/enthusiast.

http://www.nitrodynesystems.com/2str...rshandbook.pdf

p.s. it is a pretty big file so give it some time to load! Also you might want to rotate the text 90deg counter clockwise for easier reading. Otherwise your neck might get sore!

Happy reading!

BK

afm

Hi BK

This is Alfonso, did you receive my e-mail with the chart?? Is the data correct for the engines you've tested?? Have you more data to input? I'm interested in more info on Mega engines.

Have a lot of reading to do from your PDF file

Alfonso

EdwardN

iTrader: (1)

Hey BK. It is really nice informative book. Where did you dig it?
I downloaded it already. Do you have russian version of it, because now I have to go to Dictionary.com to translate some words.

mxwrench

iTrader: (1)

Hello Alfonso, Yes I received your email as well as Raniers. I will look over the chart and add any good info I can, but as time permits. I have a full week ahead of me so I will have to fit it in as best I can. Enjoy the PDF. LOTS of great info in that book. Probably more than the average brain can absorb!

Talk to you soon.

BK