Another Karl Benz 1886 Engine and Motor Wagon.

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Ken Brunskill

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I am very sorry for my delay in replying.
There is a gap of 33.5 mm from the top surface of the piston to the top end of the sleeve, @TDC.
I am very sorry for my delay in replying.
There is a gap of 33.5 mm from the top surface of the piston to the top end of the sleeve, @TDC.
Wow, that is quite a gap. I have designed the piston to be at TDC when it is just below being tangent to the Spark Plug hole (toward the crank), which I have at .280" (7.1mm) from the top (Head end) of the Cylinder and Liner. I'm making the Liner shoulder wide enough to have the Spark Plug thread through the Cylinder and Liner + a bit for material strength.

I just about have the 3D modeled in Solidworks, with all parts moving as they would be in the operating engine (learning as I go) now to get the cam to compress the Exhaust Valve Spring and I'm there, I think :-| !!!
 

Ken Brunskill

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Ken.
As you are making this from scratch at a smaller scale you should know that the design, as is, gives a very low compression ratio. Something like 2 - 2.5 : 1. This is insufficient to make the engine work consistently well. You should design the head with a spigot rather than a recess and maybe increase the piston length in order to increase the compression ratio to at to 4.5 - 5 : 1.
Tony,

At the moment I have the stroke at 1.500" (38mm) and a .875" (22mm) OD piston. I've yet to work out what the volume is in the head cavity where the Exhaust Valve lives, with your comment, I will put that on the to do list.
 
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