PeachParts Mercedes-Benz Forum - View Single Post - m104.980 piston and comp ratio help please!

carat 3.6 amg · #1 02-02-2014, 02:42 PM

Hi all,

I'm in the process of building a 3.4 kompressor engine based around the m104.980 block, and I'm going to need to reduce the piston height in the bore by a fair bit. Ideally I would like to machine a safe amount of metal from the top of the pistons, then use a decompression plate to take it the rest of the way.

Pics of my problem!

This is the block of a normal m104.980, the piston sits .6mm above the deck in standard form:

Now with the new crank/rod combo the piston is sitting 3mm above the deck:

The blower setup I will be using:

Now for my questions!

-Since the engine will be boosted by up to 1bar of pressure, what compression ratio would I need to achieve?

-How much can I safely machine from the crown of a standard piston?

-The normal m104 piston is .6mm above deck, how much below deck should it sit to achieve the ideal compression ratio? .4mm maybe?

Thanks in advance guys!