i think i had an epiphany. engine design. - JeepForum.com
 
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post #1 of 13 Old 12-21-2012, 09:58 PM Thread Starter
WJlover
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i think i had an epiphany. engine design.

So, im driving my cab down the highway, and i have this thought...

Pistons.
what if the head were slightly concaved?
in theory (or in my head) it seems as though it would be able to force more out resulting in more power.

now, im certainly no expert, or else i wouldnt be driving a taxi for a living.
but i do have a slight, SLIGHT amount of engineering knowledge. or i just think im some sort of engineering prophet.


thoughts on this?
this isnt something im looking to create and try, or am seriously curious about. its just one of those random thoughts you have. so any criticism is good criticism.

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post #2 of 13 Old 12-21-2012, 10:30 PM
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You mean something like this Hemi piston?


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post #3 of 13 Old 12-22-2012, 01:32 AM Thread Starter
WJlover
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no, quite the opposite.

take a flat piston head, and turn it into a shallow crater.
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post #4 of 13 Old 12-22-2012, 04:30 AM
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I think theyre called dished pistons, used to lower compression ratio....ocg
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post #5 of 13 Old 12-22-2012, 04:43 AM
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no, quite the opposite.

take a flat piston head, and turn it into a shallow crater.
Like a diesel. Head flat, piston dished. Nothing new.

Even Renault did it that way on their POS 1.7 liter gasoline engine. There you go.

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post #6 of 13 Old 12-22-2012, 04:44 AM
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You mean something like this Hemi piston?

Beautiful!!

Local machine shop has one head for a 58 Hemi 392 engine for sale. I almost bought it as an art piece for my garage.

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post #7 of 13 Old 12-22-2012, 08:38 AM
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Just out of curiosity, why would you think they would get more power? Not trying to be an ***, just curious about your thought process.
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post #8 of 13 Old 12-22-2012, 11:27 AM
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The more you make a piston convex, the more compression you would make. Thus, more power. Concave pistons would decrease power.

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post #9 of 13 Old 12-22-2012, 11:51 AM
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having the head protrude into the combustion chamber would almost certainly make hot spots

there is a design where the cyl head is near flat , its a great design and you can go up to 12.to 1 compression on street gas
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post #10 of 13 Old 12-23-2012, 02:50 AM Thread Starter
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Just out of curiosity, why would you think they would get more power? Not trying to be an ***, just curious about your thought process.
well, my thought process kind of came from swimming.

when you paddle, you cup your hands to kind of push more water more effectively i guess. or, however that really works.
so i figured, if you did the same with a piston, it could have the same effect of the exhaust gases its pushing back out.
less aerodynamic sounded efficient in this case


like i said im certainly no expert, and i have no problem admitting im more than likely dead wrong in my theory. but until you ask the smarter guys, you never know!
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post #11 of 13 Old 12-23-2012, 05:00 AM
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direct injection pistons are getting pretty cool looking , they stick out quite a lot so you could have a point there about the heads


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post #12 of 13 Old 12-23-2012, 10:37 PM
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Originally Posted by 970001zj View Post
having the head protrude into the combustion chamber would almost certainly make hot spots

there is a design where the cyl head is near flat , its a great design and you can go up to 12.to 1 compression on street gas

409?
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post #13 of 13 Old 12-27-2012, 01:36 AM
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You have to remember that the exhaust pressure in the cylinder might approach 1000 psi at exhaust opening. This by itself causes a large pulse of pressure in the exhaust pipe. Then you have exhaust overlap where both the intake and exhaust valve are both open at the same time. Add in pulse tuning from the exhaust system and the piston shape has a much smaller role to play in exhaust evacuation. But it does have a big role to play in intake charge swirl and tumble as well as quench and emissions. So your right it would have some effect but it would have to work within the framework of the whole intake/exhaust conduit.
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