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multicyliner 2 strokes

Old 04-20-2007, 11:29 PM
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Default RE: multicyliner 2 strokes

jeez everything always go's off topic and go's to a flame war.

really the only way to get the fuel and air into the cylinders without a blower is to direct it into the crankcase, for an inline engine it would be possible to seal the crank pin of each piston from the others and use the crankcase to get the fuel to the cylinder, with a v engine it will never work though.

if you think about it though, a blower isent all that complicated as long as your not aiming to run high intake pressure, it would be fairly simple to make one yourself, as runing some great amount of intake presure in a two stroke is pointless so it would be easy to make a fan and housing that can push alot of air at one time, but at low presure


Old 04-21-2007, 05:19 AM
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Default RE: multicyliner 2 strokes

If you want to use a principle such as that, just copy the basic idea of a 2S diesel. Piston poorted intake, camshaft controlled exhaust valves, oil in sump, with no need to isolate individual cylinder crankcase volumes, as no intake passes through the case. Then you will NEED a blower, as all 2S diesels depend on intake boost to fill the cylinder, but you'll need to re-think low pressure, and start considerring 6+ lbs boost. And remember to properly calculate blower boost you must first know cylinder volume(displacement), multiply that figure by your maximum RPM desired figure, and you have how many cubic ft per minute of air will pass through the cylinder at normal atmosheric pressure....now figure the "boost" presure, and you can begin designing the supercharger....
Basicly all you're doing is modelling a Detroit Diesel, or Electro-Motive Diesel, with the exception of either spark(natural gas or gasoline fuel) or glow ignition(nitro model fuel)...
So many variables, but untill a person has seen, worked with, studied, or even understands how these engines work, I doubt they can grasp the concept of true design....

But we dgress......sapper doesn't want to be botherred with designing a cam....
ORIGINAL: ttoks

jeez everything always go's off topic and go's to a flame war.

really the only way to get the fuel and air into the cylinders without a blower is to direct it into the crankcase, for an inline engine it would be possible to seal the crank pin of each piston from the others and use the crankcase to get the fuel to the cylinder, with a v engine it will never work though.

if you think about it though, a blower isent all that complicated as long as your not aiming to run high intake pressure, it would be fairly simple to make one yourself, as runing some great amount of intake presure in a two stroke is pointless so it would be easy to make a fan and housing that can push alot of air at one time, but at low presure


Old 04-21-2007, 07:25 AM
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Default RE: multicyliner 2 strokes

i really find that troubling that your judging how much we all know, even though you proberly know little to nothing about our experiences with engine, myself i have been working with my father on desiel train engines since i was very young, and a lot of them are two stroke i think i know enough about how engines work to have a good idea about what i'm talking about. (please dont start with the, "what type of engines?" stuff i didnt take note when i was 6-13 years old, i was interested in what was on the inside not the name)

to get maximum power and efficiency out of a two stroke engine you need to use direct fuel injection, then no fuel is wasted out of the exhaust at any rpm, and no need for a tuned pipe, but then theres the added complexity which you proberly dont want to add.

and 6 psi of boost really is very small amount, most turbo cars (eg Subaru impreza, Mitsubishi lancer evo) run around 20 psi of oost( although Volkswagen's twincharger system makes 45 psi of boost).

the most common place to see such little boost as 6 psi is large displacement normally aspirated engines converted to run a turbo, or supercharger (this is big here in Australia with the chevy ls1 and ls2 engines in holden or hsv cars) superchargers are largly the same as turbo, except the norm is around 12 psi of boost because they are usually used on a larger engine.

Old 04-21-2007, 08:58 AM
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Default RE: multicyliner 2 strokes

Cool......go for it. I certainly have not yet acquired the vast resources of knowledge y'all have at your disposal. LMAOROTF!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!! Chilluns, where would we be without 'em?

Besides, at the ripe old age of 15, I doubt you know 1/10 of that you think you know.....
Old 04-23-2007, 09:40 PM
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Default RE: multicyliner 2 strokes

After reading some of this young mans writings here,he sure as heck seems to know a lot if he is only 15.I think you would be on the right track with what you are trying,thinking in terms of using fuel injection.I'm trying to think,why would someone get huffy with you over a question.There are always people in the back ground saying it can't be done.They are usualy proved wrong on a daily bassis.Keep banging away on it and I hope it all works for you.Don't be afraid to ask,thats sometimes the only way to learn.And one thing I have noticed here on RCU you have a good chance of finding someone who might have the answer you need.Again good luck-------------BIGMIG
Old 04-24-2007, 02:05 AM
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Default RE: multicyliner 2 strokes

thanks bigmig, but fuel injection in two strokes isent my idea lol, yamaha and i think some other company's use it in there two stroke atv, snow mobile, and jet ski engines (now before someone go's to correct me i know yamaha has gone to an all 4 stroke line of snow mobiles).

i know for my age i have alot of know how when it comes to engine, but really i'v been around things with them my whole life, from as long as i can remember dad would get me to help take apart and rebuild all sorts of engines so i'v taken note of alot of things.
Old 04-24-2007, 07:36 AM
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Default RE: multicyliner 2 strokes

Still with a lot to learn though BigMig......
http://www.rcuniverse.com/forum/m_57...tm.htm#5748461
ttoks might yet posess a "basic" knowledge, but has a LONG way to go before i'd let him change the oil in a lawn mower.
Old 04-24-2007, 08:23 AM
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Default RE: multicyliner 2 strokes

you can belive what you like, from my personal experiance with motorbikes i get best life out of my engine with good enough power with my ignition timing slighty after top dead center, this means theres less presure in the combustion chamber, that means lower temps, lower operating temps and in the long run you get more out of your engine, also the reason engine fire before tdc is so that the fuel has the chance to fully ignite by time it piston reaches the top of the cylinder, all fuel should be burned by 20 degrees after top dead center with the perfect timing for max performance.

also will you leave you petty insults at home, they're not needed here, you can read all you like but you will never have the experience to back it up without going out there and doing all of this, and not only experience with engines, but had the balls to have a fidle around and see what doing one thing does, i may only be 15 but that's not a reason to doubt what knowledge i have.
Old 04-24-2007, 09:19 AM
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Default RE: multicyliner 2 strokes

If you only knew kid, if you only knew....LMAOROTF
Old 04-25-2007, 08:15 AM
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Default RE: multicyliner 2 strokes

actually i planned on for the inline having each crankpin sealed off. (that seemed like the most simple design.) and for the v design i figured a way to use a type of supercharger to pressurize the crankcase using a normal rc airplane carb and reed valves to force fuel into the combustion chambers. i also found another way to totally bypass the crankcase and have the fuel spray straight into the combustion chamber. i would have to make an oil system though. but oh well. oh and that rendering i made earlier was made in autodesk inventor.
Old 04-25-2007, 05:16 PM
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Default RE: multicyliner 2 strokes

cool, sounds good, you will need a oil pump however, if the crank dips into the oil it just splashes it everywhere and it foams up, and foam is mainly air, air isent a very good lubricant lol, so you will need to put an oil pump in it and figure out how to get it to the wrist pins.

some oil designed for desiel engines have de foaming agents in them so that might work, but after a while they start to break down and the oil will start foaming anyway.
Old 04-26-2007, 06:46 AM
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Default RE: multicyliner 2 strokes

thats what my dad was tellin me the other night how some oils will foam up. im thinkin that would be the only way wo using a pump.

oh and beelzebubishere. guess what! my computer aided doodling skills just got me first place in the skills usa state competition. now i get to represent the state of florida in the nationals for technical drafting.
Old 04-26-2007, 08:14 AM
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Default RE: multicyliner 2 strokes

you could look into de foaming agents, i'm not real sure because i havent worked an to many desiel engines (well not recently anyway) but for a small scale engine it may work, although my advice is to use an oil pump much less risk then, having the crank dip into the oil can create all sorts of problems, in the full scale counterpart if an engine is over filled with oil the back seal will go real quick from the pressure waves crated by the crank, almost always followed by the front seal, and then you got yourself a pisser, and they're messy, then it spits more oil up onto the cylinder walls while the pistons near the top of it's stroke so the oil seal ring gets alot more load then it needs (i assume you'd be useing piston rings of couse lol) and not only that but it robs power from the engine and puts more stress on the crank, this is a big project, if you get all the way you are defiantly putting pics up and a vid of it running lol, i just wish i had the patients and machining expertise to undertake something like this
Old 04-26-2007, 08:44 AM
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Default RE: multicyliner 2 strokes

yeah that was another thing i was worried about. i had originally planned on putting it into an rc car and i think if/when it flips over its going to stall every time. oh and i kinda planned on it taking a long time to make. my dad is prob going to help me w most of the machining and stuff. (he was a design engineer and machinist at florida state university.) right now he is a mill tech working with 5 axis mills. those things are awesome! ne way. im also working on another engine design but dont talk about it much at all bc when im done w it i want to get a patent on it. (that is if it works the way i plan)
Old 04-26-2007, 04:57 PM
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Default RE: multicyliner 2 strokes

you could still put it in an rc car no problems, just make it a big one, and an on road one.

good luck
Old 04-26-2007, 05:04 PM
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Default RE: multicyliner 2 strokes

Yamaha has a V4 and V6 outboard boat engine, 2 cycle of course. No "blower" required.
Old 04-26-2007, 06:11 PM
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Default RE: multicyliner 2 strokes

Yeah....so has Mercury(even V-8's), Evinrude, Johnson, Koenig, Suzuki, Yamaha, Honda, Proton...... And as for anti foaming agents....OMG! How do all our automobile engines survive without diesel oil, and how many millions of 4 stroke industial type engines have used "oil dipper" systems: Briggs and Stratton, Waukesha, Lloyd, Tecumseh.....and what was Henry Ford thinking using a "dipper" system on Model T's and A's.......[:-] Sure things have developped and improved in the last 100 years of IC engines.....but to say it won't work....when it DID for years...youthful inexperience.

LMAOROTF!

Old 04-27-2007, 02:03 AM
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Default RE: multicyliner 2 strokes

every single modern engine you will find anywhere uses an oil pump, and so modern oils are not being made to have an object hitting it 12,000 times a minute.

Desiels use anti foaming agents because of the vibration created from there running (anyone with even a small amount of knowledge knows desiels run very high compression ratios and the combustion temps in a diseil are a lot higher because of the comprestion ratio), that can cause the oil to start foaming, normal engine oil made for use in petrol engines don't have anti foaming agents because they'er not needed.

and yes it DID work, but it DOESNT anymore because there are better solutions, if you read through my posts you will find that i said it CAN work but it's alot less risky to just use an oil pump, in fact the only place you will find an oil dipper these days will be low speed low power applications like lawnmowers, and even then the entier crank doesnt get submerged into the oil, only a small dipper rod conected to the end of the big end of the con rod hits the oil.

on a personal note beelzebubishere, what is your problem? do you actually believe that your right or is it a pride issue? do you not like the idea of someone thats still in there teens knowing what they're talking about for once instead of the other way round? if you want to comtinue to argue you can argue with yourself because frankly i'v had enough of your childish way of dealing with this.
Old 04-27-2007, 07:50 AM
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Default RE: multicyliner 2 strokes

A properly designed engne, even the Model T, was not designed for the "crank" to hit the oil.....only the extended dippers on the rods.

Most modern oils, some more than others use anti foaming agents. Diesel oil manufacturers use higher contents of phosphorus and zinc to help protect engine components under high compression loads, such as compression, and shear. BUT Diesel fuel has a lower combustion temperature than gasoline. The fuel injectors depend on the fuel burning at the correct rate and temperature for a long life. If the combustion temperature is raised long enough, it will start to cook right in the fuel injector and turn into carbon. These microscopic carbon particles will abrade the nozzle. High combustion temperatures alone will shorten fuel injector life.
The real need for anti-foaming agents is in heavy equipment, doziers and such, where extreme vehicle angles on rough terrain do occassionally bring the oil into contact with the crank, the same as Marine diesels in rough seas....THAT was where anti-foaming agents came into being.

Seems you finally picked up on the "dipper" concept here.... But if your buddy here finds designing a cam too difficult, a proper oil pump, drive, and associated "plumbing," will really blow his mind.

On a personal note....I don't choose to argue with children, only correct them when they let their youthful exhuberance overs ride fact. And in fact I try to offer assistance to direction as I did at the beginning of this thread....but once a youngster throws it back in my face, or assumes handing daddy tools on a job or 2, overrides 40+ years of exposure to someone who built racing engines for a living, I sorta lose interest in that individual. And if I see a real desire to learn, I hook those youngsters up with someone that can really teach the finer points of design, assembly, and maintenance of HP engines...... Those kids are usually 1 in a hundred, out of those, 1 in 10 actually want to learn...

ORIGINAL: ttoks

every single modern engine you will find anywhere uses an oil pump, and so modern oils are not being made to have an object hitting it 12,000 times a minute.

Desiels use anti foaming agents because of the vibration created from there running (anyone with even a small amount of knowledge knows desiels run very high compression ratios and the combustion temps in a diseil are a lot higher because of the comprestion ratio), that can cause the oil to start foaming, normal engine oil made for use in petrol engines don't have anti foaming agents because they'er not needed.

and yes it DID work, but it DOESNT anymore because there are better solutions, if you read through my posts you will find that i said it CAN work but it's alot less risky to just use an oil pump, in fact the only place you will find an oil dipper these days will be low speed low power applications like lawnmowers, and even then the entier crank doesnt get submerged into the oil, only a small dipper rod conected to the end of the big end of the con rod hits the oil.

on a personal note beelzebubishere, what is your problem? do you actually believe that your right or is it a pride issue? do you not like the idea of someone thats still in there teens knowing what they're talking about for once instead of the other way round? if you want to comtinue to argue you can argue with yourself because frankly i'v had enough of your childish way of dealing with this.
Old 04-27-2007, 08:46 AM
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Default RE: multicyliner 2 strokes

i have had enough experience with engines in my short time to know what i'm talking about or i wouldnt post it, and you will find if you read my post histery that when i know that i'v posted incorrect info that i gadly take name for it, i know i dont know everything there is but i know what i have posted is all true, from experience and from reading, if you think i am trying to learn all i can you are right you surely know yourself then from a performance point of view that an oil pump is the only way to go, all i did was call my opinion, and have a read back i never said that it was imposible to have no oil pump, but it's a less attractive option for a lot of reasons.

now after having my rant, i'm willing to offer an apology for this senseless arguing on both of our parts not just your own but mine as well (as well as taking over vipers thread with that arguing) but only for an apology from you in return, what do you say? after all we both know that i'm not going to deture you from what you believe, and you are not going to be able to deture me from what i believe.
Old 04-27-2007, 09:38 AM
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Default RE: multicyliner 2 strokes

I don't need your apology kid. You don't know quite a lot yet, ie: diesel combustion temps, engine timing, reason for anti-foaming agents...... and your beleifs, are not facts. But you hold tight to them, they're yours. So I'd advise you to check your postings...you have quite a few errors there.

I teach and advise based on facts, not beleifs, and to think I'll apologize for that. Furthermore to think I'd apologize to certify your apology.....well let's just say they'll be installing air conditioning units in Hell, first.

I'm done with this thread.
Old 04-27-2007, 12:06 PM
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Default RE: multicyliner 2 strokes

im done here too. this isnt going newhere. i already found the solution to my original problem from other sources at work. and just for the record beelzebubishere, i never meant to throw it back into your face or offend you in any way. and yes i am very intrested in learning. oh and thanks for the help ttoks.
Old 04-27-2007, 06:37 PM
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Default RE: multicyliner 2 strokes

it's your own loss, i offerd a mature solution and you'v show how immature and stubern you are by rejecting my offer, in the world of aceing engines evrything you say proberly is correct, but i dont live there.
Old 04-30-2007, 11:26 PM
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Default RE: multicyliner 2 strokes

ttoks, VIPER458, I personally commend you both on offering apologies and even more so, your willingness to learn and even be willing to admit where you are wrong and ask "Okay, where am I wrong and what is the correct manner?"

You guys are quite knolwedgable and understand the principles, keep up your endeavors and continue to learn. In no time, you will actually be doing design engineering (if you young prodigies arent doing that already). Yes, the comments seemed negative, but you guys showed much more maturity that even I had when I was your ages. Dont let others dissuade you with their own opinions, though you have your own, you will find the facts (if you guys havent already) and your opinions will be substantiated. Even if you discover you are wrong, you will gain more knowledge. Even the greatest minds look back over their works and realize and say to themselves "I was wrong!" Newton, Einstein, Leibnitz, and other great minds all amended their works as they dicover their errors and from learning their errors and finding the truths, and they eventually developed brilliant theories.

Though I would love to have seen calculations and fomulae, I dont doubt you guys are capable of calculating moments of inertia (particularly by way of the parallel axis theorem), odd shaped volumes rotated about a given axis (Pappus-guldinus throerem), mass flow, and more. What they teach in high school today is quite stunning and I can see these things within your grasp. Math skills up to calculus and a knwledge of physics up to harmonics are all that is required and you guys can learn differential equations on your own to calculate heat propegation, fluid flow, materials stresses and strains, etc. just by finding the appropriate books. All these things will aid you in your engine designing endeavors; all you really need to know is the burn rate for a given fuel-air mixtre and the potential stored in that fuel-air mixture (BTUs per given mass unit) and you can design around that.
Old 05-02-2007, 02:11 PM
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Default RE: multicyliner 2 strokes

You know, Both of you are sort of right. In racing a lot of people would piss around with the idea of foaming oil and how you had to use synthetic oils (sp), But honestly I didn't see any difference, now granted I changed out my Valvoline non synthetic oil out everyrace for one reason or another. But the amount of foaming may not be all that significant to the lubrication of the engine in the short run.

Now to back up the oil pum theory with some non factual thinking. Allthough most engines had "slingers" their life never lasted all that long. But now these days where everything has an oil pump it seems that they keep on a going beautifully, even if you miss that 3000 mile oil change.

Please keep in mind I am being lazy in typing this out and not really trying to prove anything, but just throwing in some nonsense.

Flame away if you wish, i prolly won't see this for another few weeks anyways

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