M103 3.0 to 3.6 Build Discussion - PeachParts Mercedes-Benz Forum

ptoro01 · #1 10-24-2006, 09:07 PM

So the mystery has been out there, will a 350SDL crank fit into an m103, what else is needed to make this work and what will it actually do? Instead of a 350SDL crank for the conversion, would a C36 bottom end work better.
The last few threads date back to 2002 about this when most of us simply dismissed it under the fact that its too expensive.

Chime in if you have done this or if you have done research and you got stuck somewhere. And hey, if anyone wants to send spare parts my way, I can put them in the spare engine I have.
Let the brainstorm begin!!
Pete

newbenz2 · #2 10-24-2006, 09:17 PM

I thought the 350sdl crank fit in the m104... Thats what I'm doing to my 104.... To my knowledge the m103 doesn't accept the 350sdl crank.... the crank will bring a m104 2.8 to a 3.6...
Kevin

300EVIL · #3 10-24-2006, 09:19 PM

Hi Pete,

From what I have "heard", from more than one sorce, the M104 3.2 block with the 350SDL 0M603 crank and M104 2.8 rods was used to make the AMG 3.6L M104. I have not personally performed the calculations to confirm this, but it sounds about right. The 3.0 M103 has a bore of 89.0MM and a stroke of 80.25MM. The M104 3.2 is 89.9 X 84.0 and the M104 3.6 is 91.0 X 92.4. This means that the 3.6L displacement is an enlargement of both bore and stroke. According to Ortolan, the 3.0 M103 will make 3.4L with C36 parts using stock (I think) pistons. Do the math and that should come out right. As for the crank, I don't know but it may need some alterations on a crank lathe in order to fit an M103/104. I suggest you contact Ortolan and ask him for the measurements of his C36 crank and rods to make sure.

Ortolan · #4 10-25-2006, 06:22 AM

While researching the project I read that increasing the bore of the M103 left the cylinder walls too weak. Apparently the Brabus 3.6L had a very short lifespan. This is why I elected to leave the bore alone and only increase stroke. The increased stroke also reduces the chance of detonation at the same compression ratio.

brabus3.6 · #5 10-25-2006, 08:54 AM

Quote:

Originally Posted by Ortolan

While researching the project I read that increasing the bore of the M103 left the cylinder walls too weak. Apparently the Brabus 3.6L had a very short lifespan. This is why I elected to leave the bore alone and only increase stroke. The increased stroke also reduces the chance of detonation at the same compression ratio.

From whom did you hear of the 3.6's apparently short lifes[an & what do you deem to be short? I have a Brabus 3.6 which has done over 130,000 miles, still going string (touch wood). I've done all the top end work (valve stems & guides, head gasket) due to a head gasket failure at around 100k but this is a common M103 fault. The car does consume some oil, in the region of a quart every 700 miles but tuned engines are such and I'm using Mobil 1 15W-50 Fully Synthetic, I may switch to a semi-syn as I've heard this will cut back consumption and may be better for an older engine.
The torque increase from boring the engine should not be overlooked. This really increases low down torque significantly well still having an apetite for the heady heights of 6550RPM. Do it!