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IC ENGINES? Answered

I was thinking that what will happen if we arrange inlet & exhaust valves on the piston (spark plug remaining on cylinder head)?
i think that may be by using metal foam on the cylinder head the knocking of the engine might decrease.
please assume that somehow i use proper mechanisms for valve timing & they dont have any appreciable effect on the piston.
just consider that the weight of the valves is added to the piston.
i was wondering that this might increase the efficiency of the engine because suction will take place more slowly (so it will near a reversible process, so efficiency will increase) & force of the explosion will be better.
please you ppl; if anybody can give me satisfactorily explanatory answers, do reply!



If you want neater valves, there are 2-strokes that still use ports rather than mechanically-driven valves. There the pistons are part of the valve arrangements.
You might also look at sleeve-valves, but they have problems.

Your idea is interesting, but should remain an idea because it's got too many problems to make it worth even drawing diagrams.


2 stroke engines have way too many problems, important among them is air pollution. hence these engines are banned in our country.
i have replied to ICENG & may be u will understand what i am trying to say.
my main objective was to reduce the noise of the engine by this arrangement + may be i think that it will increase the efficiency of the engine.
& thank you for answering my question : )

Think about the cylinder:
Head-end, round.
Piston-cap, round.
Cylinder-bore, cylindrical.

People have put valves in the cylindrical part (as the examples I gave before)
People have put valves in one of the round parts.
>Why only in the cylinder-head, and never in the piston cap?

I'll start you with this: how would you redesign the inlet and exhaust manifolds to go inside the crank-case and connect with the ports in the piston?
Can you post us a diagram of that?



7 years ago

One thing you got to believe, any time you decrease airflow you severely reduce an IC engine power and efficiency.
Just stick a potato into a car exhaust and see what happens.
Making air flow reverse, slows it hurting power output and efficiency.


i am not restricting the air flow; rather i am increasing it....
well, you must be knowing that for an irreversible process to take place, the speed of the process must be infinitesimally low.
so, by slowing the suction process, i think that i am nearing the reversible process.
thus air fuel mixture will be sucked in more amount.
(if the piston moves fast to B.D.C. then not all the volume above the piston will be filled by air fuel mixture; there will be some vacuum; to be precise the density of air fuel mixture will be less)(thus by what i am doing the density of air fuel mixture will be more.....hope u can realise this!)
hence power will increase!
please correct me if i am wrong.
& thank you for answering my question : )

Sorry you confuse me,
You say both ? :
"to be precise the density of air fuel mixture will be less)(thus by what i am doing the density of air fuel mixture will be more_ _ _hence power will increase!"

Keep in mind the stoichiometric ( fuel to air ratio ) is the peak IC engine power and eff.
If you increasec the fuel to air ratio you risk burning the IC engine with lower power and lower eff.
If you lower the fuel to air ratio the power is reduced with less eff.

Granted peak power and efficiency do not occur at the same point, but close enough for explaining IC concepts.


getting the valves to open and close might prove difficult Personally I can't see any advantage - motor manufacturers are pretty well up on how the Ic engine runs and as yet have come up with few radical modifications to the basic design.

with what i am doing, there is no need to control the valves!
they will operate on their own(by using a very very little power from piston).
may be u must be knowing the function of turbo super charger in racing vehicles.
thats exactly my task is.
+ there will be noise reduction(i have detailed in my question how this will happen)(but i am not so sure how much noise will be reduced, rather it might increase)
please tell me if i am correct.
& thank you for answering my question : )
please do reply , sir.


7 years ago

There are problems with that idea on so many levels.
Even if you could figure out a way to actuate the valves using servos and wireless controls, you will have increased the mass of the piston substantially. The connecting rod will have to be enormously strong, as will the crankshaft. Imagine a tennis ball tied to a length of cotton kite string with the other end of the string secured to your wrist. Now throw the tennis ball as hard as you can. The string might be strong enough to stop the tennis ball without breaking. Then try it with a baseball. The additional mass of the baseball will likely break the string.
The piston and valve assembly will have to withstand thousands of hammer blows per minute from the fuel/air ignition, not to mention the forces delivered by the abrupt changes in direction of travel. How do you keep the assembly from flying apart?
How do you port the fuel/air mixture to keep it separate from the exhaust gases?
I could go on but those are just a few of the myriad of problems such a design poses.
Sometimes there are reasons no one has ever done it before; it simply isn't practical, if it is even possible.

well i am not using servo's & wireless.
i am doing this by simply using 2 rods (only their weight will be added on the piston) on the underside of the piston (but connected to the piston rigidly) & a special element which is not even connected to the piston.
the 2 rods have 1 hole each which are the inlet & outlet for gases.
so tell me how will the connecting rod or the crankshaft suffer damage?
this is applicable for 4 stroke engines (although it is more advantageous on using this on 2 stroke engine; however these engines are banned in our country!), & the valve timing is as usual.
just tell me if by doing this i will get more power or not?

"Sometimes there are reasons no one has ever done it before; it simply isn't practical, if it is even possible." --- i hope u know who built the first mechanised printing press. people in his country gave him the same reply as yours.....
i dont want to tell u that i am great or anything like that, but rather to have an attitude of questioning everything around u & asking the most important question "WHY NOT THIS???"