# engine torque

Their is a question in my mind 4 which i cant get any answer...i m posting it out here...

We all know dat in an engine at the time when d piston is at its TDC d combuston takes place(under some variations...but ideally at TDC)i.e. d pressure force is maximum at this position(power stroke)...but at dat time d crank and d connecting rod forms nearly a st. line ... which leads 2 nearly zero Torque(as the pressure force vector almost passes through the crank center)...but still d engine is designed like dat 4 which we get zero torque generated at d time of power stroke...WHY??

## Replies

• xheavenlyx
I dnt no wat a "d piston" looks lyk nor wat a "TDC d combuston" iz.

Anyway, if you asking why there is motion when the piston / crank / rod are in the same line, then the answer is that, at the time of motion (considering we analyze form t = +0 i.e after motion has already started) then the crank has inertia which makes it move out of that 'no torque' zone.

Now how is it that the crank has motion in the first place? That because of the initial combustion.

TIP: Try 2 rite n englsh.
• mecsumit
well thanks 4 ur tip....
actually wht i want to know is that : it would be benificiery (??) if we have torque from the max pressure force applied on the piston at TDC... but instead of that the prevailing engines have 'no torque' zone at that 'max pressure' zone....
the question is why????
• xheavenlyx
Thats because you are translating a linear motion into rotational motion, and that kind of technique has lots of involved physics. Now I did not get your idea, but if you can give a nice drawing xplaining it, might be helpful.

And if I am guessing right, the max pressure zone is very neccessary, since it is the begining of your high torque zone. In the right books you can get a good read with graphs and drawing. I am not a mech guy, but this is all I can say. If I sit and research, that will take my time away from electronics 😀 You can do the mech research right? then let us know you method in good detail with drawing, and please document your stuff. Then you dont have to worry about your idea getting stolen.
• wm1_99
power= torque x speed / k
k is determined by units of measure

horse power= torque x rpm / 5353
torque is pound feet
rotational speed is revolution per min

kW= torque x rpm / 9549
torque is newton meter (N.m)
• mecsumit

This is a traditional 4 stroke engine... showing the power stroke at 3.
• mecsumit
i cant get u... wm1_99
how could that b the answer?
be more clear
xheavenlyx
I dnt no wat a "d piston" looks lyk nor wat a "TDC d combuston" iz.

Anyway, if you asking why there is motion when the piston / crank / rod are in the same line, then the answer is that, at the time of motion (considering we analyze form t = +0 i.e after motion has already started) then the crank has inertia which makes it move out of that 'no torque' zone.

Now how is it that the crank has motion in the first place? That because of the initial combustion.

TIP: Try 2 rite n englsh.
I am agree with u!
It's simple.
• zaveri
mecsumit
well thanks 4 ur tip....
actually wht i want to know is that : it would be benificiery (??) if we have torque from the max pressure force applied on the piston at TDC... but instead of that the prevailing engines have 'no torque' zone at that 'max pressure' zone....
the question is why????
in real cases the crank and connecting are not in the same straight line but they will be inclined at an angle not equal to exactly 180 degrees

the crankshaft is already rotating due to inertia , and at the same time the piston receives power. all these factors cancel out the effect of the zero-torque zone.

You are reading an archived discussion.

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