M103 rebuild bottom end more power? - PeachParts Mercedes-Benz Forum

ps2cho · #1 05-29-2010, 09:45 PM

So I was thinking about buying a used 103, stripping it down and rebuilding it for a straight swap. I heard that Brabus did a 3.6L M103? How did they do this?

What sort of power could I get out of refreshing the bottom end with different components?

Would the K-Jet system need modifications or would it be literally just a block swap? What about the difference between the 722.3 and 722.4 when it comes to handling HP? Are they both equally able?

Thanks!

BAD300 · #2 05-30-2010, 04:03 AM

ps2cho. I have a set of standard forged pistons travelled only 3-4k. Engine was re-stripped down due to poor LPG set up. (can read the full story in my "BAD 300E project commenced" thread)

These pistons were very costly so was keeping them for up ahead when I rebuild the 2nd hand engine I am acquiring very soon.

I could do with extra funds though @ moment so these may be up for sale soon? Worth a thought if you want serious HP!

Cheers,
Tim.

JayRash · #3 05-30-2010, 07:47 AM

the CIS is a srt swap, the CIS will cover u up to 290 -300 hp with the right mods. U might just need the fuel distributor head from the M103 3.0-24 engine euro spec
with proper work and a 3.6l capacity and 12 valve head u should expect 240-250 hp

ps2cho · #4 05-30-2010, 09:31 AM

Anyone know if the 2.6L and 3.0L block are the same? Reason is for transmission pairing.

Not quite ready to spend anything yet. Just doing some research so I can keep it in mind

JayRash · #5 05-30-2010, 11:13 AM

yes they are the same and so the gearbox of either will fit either

ps2cho · #6 05-30-2010, 02:37 PM

What sort of crank is used?

JayRash · #7 05-30-2010, 03:10 PM

what do u mean by ur question? The 2.6 and the 3 use same crank which is 80.25mm

ps2cho · #8 05-30-2010, 05:34 PM

Quote:

Originally Posted by JayRash

what do u mean by ur question? The 2.6 and the 3 use same crank which is 80.25mm

Oh I thought they used different...so did they just bore out to go from 2.6 to 3L?

MAG58 · #9 05-31-2010, 12:13 PM

See now that I'm not sure of. I do not know what the wall thickness is on the 2.6 motor if you can bore it safely from 83mm to 88.5mm 5.5mm is a BIG overbore. You'd truly have to get the block sonic tested to see if it has the wall thickness to facilitate that.

JayRash · #10 05-31-2010, 01:41 PM

Bob, is there a differance between the M103 and M104? For on my amg the block is bored to 91mm and same for the M103 Brabus blocks, those are even bored to 92 but thats beyond pushing it since i have heard of walls cracking on those blocks.

ps2cho · #11 05-31-2010, 04:46 PM

I've done my transmission rebuild...head rebuild...so I want to learn about bottom end items now as in reality I know very little...but I am always up for the challenge.

So overall, what parts/work will I need to buy/do to attain ~3.6L?

MAG58 · #12 06-01-2010, 02:01 PM

I'm not totally certain on blocks, I'm sure the .98 M104 and M103 blocks are VERY similar, hell my .98 CIS motor still has an M103 block casting number. The .94 and .99 104's deviate quite a bit from the .98 motor including the front chain tension which is totally different. My qualm with the .94 M103 is that it has a much smaller bore than the 3.0L motor. Usually companies will cast the walls with about the same thickness, so with the much smaller bore, you will not have room to make it to the 88.5mm stock bore of the .98 3.0L motors. I'm not certain of this though, so if you get the blocks sonic tested you'll be able to tell whether or not you can punch it out that large.

The original 3.6L AMG M104's used .941 coded blocks off the C280 engine line. These blocks were identical to their 2.8L counterparts in block castings, they were just bored to the max 91mm. To get 3.6L you'll need to get a 350SD 92.4mm stroke crankshaft and a 91mm bore. 3.5L is obtained with the same crankshaft but the 89.9mm stock bore of the .94/.99 M104's, 3.4L is obtained with the same 350 crank but the stock .98 bore of 88.5mm. 3.2L can be had in M103 form by using either the 3.2M104 crank or the 3.0L OM603 crank (both are 84mm) and an 89.9mm bore. Using the 84mm stroke in the 88.5mm block will net you 3.1L. I think that's all the non-standard sizes I can come up with right now. Oh wait, the stock 80.25 stroke with a .99/.94 M104 89.9 mm bore will net you a displacement of 3.05L

JayRash · #13 06-01-2010, 02:09 PM

form what i know the M103 2.6/3.0 have the exact same block just one bored more than the other, thats y the 2.6 really lacks power low down since it has a small cranck and small pistons, but it sure will hold gr8 under boost and should rev like crazy if u can get the cam to cope.

MAG58 · #14 06-01-2010, 02:16 PM

I'll probably have my 2.6 block sonic tested when I pull the motor for my 3.2L m104. If it really is the same, I'll just have it bored to 88mm (any smaller and i'd have to tulip the valves) and put the 84mm stroke crank in and see what she'll take. The 2.6 does not have the steam vents bored across the coolant holes between cylinders like the larger motors do, so I'd get more support at the top of the block. That would be nice.

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