I was actually suprized when after getting a Mercedes I saw the crossection pics of the Prechamber in the manual.

I could not believe what would have to be squeezed through the little holes in the prechamber and I had not encountered any Diesels that had something like the Ball Pin in the Prechambers.

I finally got to see a Prechamber when I helped one of the Members pull his from a scrap Cylinder Head.

What I decided is that the Prechamber is made with the little holes because the designers wanted to control and direct the combustion where they wanted it to go.

Also during compression squeezing the Air through those little holes must create some serious turbulence/velocity; and even more so at higher speeds.

My comment concerning the Piston weight has more to do with the weight difference of the Pistons at higher speeds due to inertia.

My thought on the pre-heated Piston Head is that ounce the Engine is up to operating temp the Head of the Piston (and maybe even the Cylinder walls) is much hotter from absorbing the heat from combustion than the Air Compressed by the Piston is. So I do not think the Piston Head is robbing any heat from the Compressed Air.

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84 300D, 82 Volvo 244Gl Diesel