Hi,

I'm new to the forum. I'm in here mainly because I want to get good real-life info about Mercedes M104 engines and its variates. I have played the idea what would be the IDEAL M104 for the turbocharged street car that would use as many OEM parts as possible. Would it be 3.0, 3.1 3.2, 3,4 etc liter, based on 3.0l block or 3,2. What crank and rod ratio etc?.

I went through this thread but could not find proof if the then newer M104 head can be bolted to 300-24 block? So you could benefit from variable cam timing from newer head?

I have thought of building something with good low-end torque and sensible revs and with good rod ratio.


How about building something like this:

M104 block 88,5mm bore (more meat on cylinder walls)
M104 crank 84mm stroke (from 3,2 motor)
M104 88,5mm pistons (stock)

Some aftermarket rods 141 mm (to get the rod ration to 1,68 and compensate extra stroke). As comment all Audi turbocharged cars, RB26 or 2JZ the rod ratio is 1,65-1,67.

M104 newer version head with Variable cam timing. (there are aftermarket cams available via CatCams 268°/257° - 230°/220° - 10.45mm/10.15mm - 1.55mm/1.00mm.

With the newer head, I bolt on the stock intake manifold, fuel rail.

The engine would end up being 3,1 litre + variable cam timing from the newer head, better rod ratio. Would that work?

Maybe changing the crank from 80,25mm stroke to 84mm isn't worth doing for displacement sake but, if rod ratio is higher than say, 1.8, piston approach speed to TDC gets very progressive, and ignition timing threshold from a knock to not making power gets very very short. So I would do it making more power . If my calculations are correct then on 3.0-24v motor rod ratio is 1,81, in newer 3.2L engine ratio is 1,73. In 2.8L engine its 2.01