machine a combustion chamber in 3.1 pistons

[moseswal2]

Hi

I have attached model of a tool that I want to use to machine combustion chambers into the pistons while they are still in the block.(PDF 3 pages)

The yellow part is plastic to protect the sleeves ant to seal it from shavings.
The blue part is mild steel that will bolt to the block and push the piston down to BDC and keep it stable so that it does not move around.
The red part will rotate inside the blue part.The cutting tool will be the shape of the combustion chamber and attached to the bottom of the red part.

I will have two cutting tools, 1 to roughf out and the 2nd to finish.

I want to use a sleeve bore machine to drive the tool because I'm not going to remove the block.

I have the head, cam and complete injection system from a 2.5 and I want put it on a 3.1. Everthing will bolt on but I need to make the combustion chambers in the pistons.

Is this crazy or can it be done.

Will the piston get damaged with the twisting force inside the block while drilling.
Is there enough meat for a 10mm (migt not be this deep) deep combustion chamber.
Will the piston fail anfter being machined.

Regards

[geeves]

If the pistop crown was 10mm thick it would melt on top as it wouldnt be able to transmit enough heat away. I dont know how thick they are but I see a holed piston in your future

[moseswal2]

Hi

It will probably only be 5 to 7mm deep. The 2.5 combustion chamber is about 10mm deep but the crown is probibly cast thicker.

Thanks Geeves If the crown is 0nly 10mm thick then it can't be done.

Does any one know how thick the crown is.

[geeves]

Better way would be talk to someone that custom makes pistons. One word of caution. These guys normally are making stuff for race motors where moneys no object. Yours will be more expensive as they are one offs. Hope you have a sympathetic bank manager

[moseswal2]

Hi

Thank you Geeves please look at attached document, shows the cross sections of Isuzu pistons. The 4JG2 T is om pg 23.

Regards

[mrstrat]

Hi

I am assuming that the 3.1 is an indirect injection engine? If so, you may find that the crown wont be thick enough for a chamber to be machined into it. Another thing to remember is that EVEN IF YOU COULD machine a chamber into the piston, you have to get the shape, the depth and location of the combustion chamber spot on etc as the injectors location and spray pattern will be optimised for the combustion chamber. another thing: compression ratio changes? Compression pressure changes due to removal of material from the piston... Also soemthing to think about: Is the combustion chamber in the 2.5 a separate machined piece (possibly steel for heat tolerance) that is cast into the piston during manufacture?