So I've been a member of peach parts on and off over the years. Etc etc blah blah.

About a year ago I got really sick and tired of my 2.6 201. Just sluggish and boring to drive. Had a few spare 103s laying around as one does.... Decided I'd swap for a 3.0l. But in thinking about the measly 20 odd horses it would gain decided some modification was in order. So I started researching, i had an early (86) from a 124 3.0. and a late (91) 4matic engine.

I decided I'd do major porting on the head, get a dbilas camshaft and see if this mystic piston/head mismatch for high compression could be achieved. This is my journey.

I started with a late spare 103 head, cut it straight down the middle of the chamber. In a quest to figure out how much material I could remove. I was going to be using the early head, but figured the castings were close even if the chambers were different. And I was right! They did however on the late "hemi" head move the intake valve ever so slightly. Which is why if you look at the dished pistons and compare to the flat tops the reliefs are in diff spots(intake only).
So I did major port work to both the intake port and the exhaust. Raised roof, bowl work, cut down the guide boss, squared the port floor. Left the chambers alone. Ordered the BIG BOY from dbilas 288* cam with springs and lash plates.

In the interim i started mocking the pistons and ported head to see what the valve clearances looked like using an old HG. Made my own relief tools from old valves and took a drill and cut all the flat top pistons @TDC i was planning on using. (This is when i figured out mercedes moved the valve ever so slightly). Then by hand cut more radial clearance into each one. The pistons were roughly .045 out of the bore at TDC.

Bought new intake valves, new guides(all valves) head bolts, head gasket etc etc. Had the head machined when the new dbilas 288* arrived.

I was using the 4matic block(lesser miles on it) which had no dipstick. So I drilled the block for the dipstick. Was really interested in an oil cooler, but didn't necessarily want to run an external one. Had an early m104(3.0l) laying around with the factory water cooler and figured the base of the block was 103 so it should fit. And sure enough it absolutely did. Also stole the 104 windage tray from the same engine.

I'm still assembling the motor and there's some more info I'll need to add. But boondoggle or not, the reason I built the motor was because so many people rant and rave about the 104 online. I just want to prove the 103 is just as potent or more with a little work in N/A form.

Interesting thread. Any news? pics? I also have a 2.6 in my 190 and would like to wake up the horses

Checking back in for progress/pics

Sounds like a sweet build.

Interested to hear more about putting the 3-liter m104 windage tray into the m103. The m103 can trip the low oil light when oil sloshes to one side in hard cornering.

Did you weld the 104 tray into the 103 oil pan?

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w201 + m103.983 swap

The main bearing bolts have the heads drilled and tapped and the windage tray bolts to the bolts, literally.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

Any updates here @Dirty140?