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Old 02-10-2013, 06:36 PM   #1
camnefdt
 
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Default different piston design for IC engine

I am yet to build my first anything on a lathe or milling machine, but am a super technically minded young individual driven by mechanics and general engineering.

At the moment i am busy designing out a long term project for one day when i have the experience and money to invest in such a project.

The question i have is, has anybody considered using a more modernized design for a piston over the good old straight long cylinder?

something along the lines of this. . .
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This one is from an F1 car but the concept is there.

So has anybody tried one of these for a scaled IC or even considered doing this before?



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Old 02-10-2013, 07:28 PM   #2
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I think myself I will stick to the long cylinder. Stuff like you show are designed for minimum friction and flat out performance. They are also designed to last one race and get tossed out. As my engines are not designed to go real fast I will most likely stick with what I see in production engines that are designed to run for hundreds of thousands of miles.



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Old 02-10-2013, 07:41 PM   #3
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F1 budgets are so low, the have to save material wherever they can to cut costs.


Nick

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Old 02-10-2013, 08:57 PM   #4
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Default One step at a time.

[QUOTE=camnefdt;209786
The question i have is, has anybody considered using a more modernized design for a piston over the good old straight long cylinder?


This one is from an F1 car but the concept is there.

So has anybody tried one of these for a scaled IC or even considered doing this before?[/QUOTE]


Best to take one step at a time, If you are trying to build something radical, (or just something ordinary) then start at the beginning and learn the arts of machining, casting metal etc. etc. - if these basic fundamentals are absent from your experiences then you will quickly lose interest and go nowhere.
However I do understand your enthusiasm ( much like I was really) but don't let that enthusiasm die by having impossible ambitions which are beyond your reach, at least which are way beyond your reach at the moment.

Good luck with your projects and please don't lose your enthusiasm - you could of course prove me wrong though and if you do, then I'll accept that!

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Old 02-10-2013, 09:09 PM   #5
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I can see that type of piston works, but goes against design principles where the piston should be at least as long as it is in diameter, preferably longer. This is to stop the piston cocking in the cylinder.

Paul.

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Old 02-11-2013, 12:02 PM   #6
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you are 100% correct in saying that this is purely a performance 'mod' piston. But in recent times, similiar designs (not as narrow) are being used in production performance cars purely for the fact that they weigh less and have less friction.

wildun
i dont plan to take shortcuts to achieve my goal, will start off with basics and make my up from there, i just love learning about new things mechanically and as a challenge to myself, am designing out a purely performance V8 to be actually used in a RC car (a project that is still many many moons away :P, but an eventual goal)

I am going over every single inch of the engine with a fine tooth comb to come up with the BEST possible engine with crazy performance and reliability.

Swifty
As a rule 'they' say as long as your skirts of the piston are roughly half your piston diameter there should be no cocking in the cylinder. they are also done with the top of the piston perfectly round, and down at the skirts it is slightly oval to help stop the cocking in the cylinder and for expansion.

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Old 02-11-2013, 08:22 PM   #7
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Quote:
Originally Posted by stevehuckss396 View Post
. They are also designed to last one race and get tossed out. .
For a couple years now the engines have to last for two races plus the practice and
qualifying. (F1 the only auto racing) :-)
...lew....
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Old 02-11-2013, 09:16 PM   #8
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You have to remember that F1 engines are at operating temperature before they are even able to be started. They would disintegrate if started from cold, such are the tolerances of the components.

Such a piston in a model engine could easily 'twist' within the bore, and this is often the reason behind the extended skirts. Although in a lot of model engine designs I have looked at, I'm sure their pistons could easily be reduced in height without too many ill effects. Any offsetting of the crank to the cylinder center line will normally use an extended piston skirt to combat the increased piston to cylinder pressure. The premise being that the load is spread over a larger area and with greater moments of inertia.

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Old 02-12-2013, 07:09 AM   #9
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CAMNEFDT,
Desigining something of your own is a great project, designing the best solution for achieving "crazy performance and reliability" in a model (RC) car possibly would not be by using a V8 engine! - I think you will find that a fairly high performance single cylinder two stroke engine and properly designed exhaust chamber would beat it hands down, both in the power to weight ratio, the outright power and the cost, (unless cost is no object).
Then, in the reliability stakes..... what if the engine seizes and/or breaks one of those rods you so lovingly fashioned, or bends the beautiful big long crankshaft you spent a month making? ... in the case of the two stroke, probably a reasonably simple repair and back in business!
Point is, what do you want? - to be a draughtsman/designer and let your mind roam free? to have fantastic performance - with a model V8??, To have a very reliable and competitive model car- with a model V8? - to be a competent machinist to make all this come about?
That's what I meant when I said earlier, "one step at a time" and I'll add a bit more "everything starts with a dream, but for the dream to come true it needs to be tempered by reality".

Still, no harm in dreaming - I always did, but I have also faced all the realities (and disappointments )through my forty something years in engineering, - don't lose the dreams, but pace yourself and remember, learn only one discipline at a time - but keeping the others in sight - good luck and do well.

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Old 02-12-2013, 07:57 AM   #10
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I would buy a copy of "Modern Engine Tuning by A Graham Bell". Read up on piston design , Bore to Stroke Ratio , Connecting Rod Ratio to Piston Stroke.
Forged pistons versus cast pistons , port design and cylinder block design and crankshaft design camshafts etc etc etc . This book is a bible if you are building a 4 stroke or modifying a 4 stroke engine. Better to make a single cylinder engine that you can keep making changes to so you are able to achieve quantifiable results first me thinks.



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