Ok so I found this data on the M104 thanks in large part to MAG58.

BorexStroke 89.9x84mm or 3.54x3.3in
Deck height 217.625mm or 8.567in
Rod length on 3.2L 145mm or 5.708in
Piston deck height on my 97 3.2L M104 .014" or .375mm ABOVE deck
Piston Dish -8.75cc on "X" stamped 3.2L pistons
Compressed HG thickness .022" or .5588mm
Combustion Chamber volume 48cc on 3.2L
Compression Height on X stamped 3.2L pistons 1.22in or 31mm
Piston Pin bore 22mm or .866in
Rod Journal Diameter 1.889" or 48mm
Rod Big End Diameter 2.009" or 51mm
Rod Thickness .867" or 22.02mm
Headgasket Bore Diameter 91.55mm

Deck height from what I've seen can be found pretty easily(I think, let me know if I'm wrong), by taking the stroke divided by 2(as stroke is the distance between the main and rod journal centers times 2) plus the rod length center to center plus the compression height minus the piston to deck clearance.

for my e320 I got 42 plus 145 plus 31 minus .375 = 217.625mm which just so happens to match MAG58's measurement

With all the other measurements that comes to the stock 10.2:1 compression ratio in RSR, CSG and Eagle's compression ratio calculators. Now if I used a rod that was exactly 2mm shorter than the stock M104 rod, say a 143mm Honda H22a rod(same pin, rod journal and big end diameters), then your looking at a compression ratio of 8.8:1 with the stock pistons. This was the method of lowering the compression on the M104 Twin Turbo kits of the 90's.

With a set of forged pistons in there you have the capability of 150hp per cylinder or 900hp since cheap SCAT H-beam H22a rods are rated at a reliable 150hp per cylinder.

The best off the shelf piston I have located in America is the Ford 4.6/5.4 90.2mm piston which requires the block to be honed a little but not enough for an expensive torque plate to be used. It would give a compression ratio of 7.8:1 to 9:1 because of it's huge range of dish options from -5 to -18cc.

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1997 Mercedes E320 Turbo
Garrett T3/60-1 Turbocharger
Custom Water Intercooler Setup
352rwhp/366rwtq @ 8.6psi in '08

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