Bore m103 2.6 or replace with m103 3.0?

[eliburch]

Hi, First post here so go easy on me.

I am planning a 190e turbo build for a new project. I am new to the Mercedes world but learning lots on peachparts!

Okay so my question, if I have a 190e 2.6 with about 150k miles would you rather replace it with a 3.0 also with about 150k miles or bore it to around 3.2L? My 2 main goals here are low cost and reliability, not necessarily maximum horsepower.

I am leaning towards boring it out because i could basically rebuild the engine at the same time but my concern is I would need custom pistons for like $1200 whereas I could just pull a 3.0 motor out of a junked car for much less. Are there any off-the-shelf pistons that I could use? The displacement doesn't need to be exactly 3.2. Could be 3.3 or 3.4.

There are really good machine shops near me so I'm not worried about that. Just thought I would get all of your input before contacting them because they'll probably just try to build me custom pistons.

I looked for other threads on this but didn't see any so you could point me that direction if I missed anything.

[Frank Reiner]

Originally Posted by eliburch

Hi, First post here so go easy on me.

"turbo build"

2 main goals here are low cost and reliability,

Once again, an oxymoron to the fore!

[eliburch]

Okay, Obviously the entire project will be expensive, lots of work, and not as reliable as stock. But plenty have people have turbo'd these engines reliably without costing an arm and a leg.

I'm only asking for input about boring the engine vs replacing it. Not the turbo aspect. Thats for another time.

[duxthe1]

Swap it. It isn't worth the hassle to build a low power turbo motor. These engines use piston guided rods and custom pistons aren't as easy as it sounds.

[eliburch]

Originally Posted by duxthe1

Swap it. It isn't worth the hassle to build a low power turbo motor. These engines use piston guided rods and custom pistons aren't as easy as it sounds.

Thanks for the advice! To be clear, I want to go turbo either way but it does seem like less hassle to just swap it first.

[Dirty140]

Why go turbo when you can just slap the 2.6 head on the 3.0l block? Sure smaller valves but higher compression. So i mean for the usable rpm should be great, and best bang for buck. Idk I'm a big N/A proponent. Not sure which HG you'd use tho.

[eliburch]

Originally Posted by Dirty140

Why go turbo when you can just slap the 2.6 head on the 3.0l block? Sure smaller valves but higher compression. So i mean for the usable rpm should be great, and best bang for buck. Idk I'm a big N/A proponent. Not sure which HG you'd use tho.

Mo Powah Bebe. Wanting 300+whp. But thanks for the input. Again, I'm really just looking for advice on boring vs motor swapping. If anyone has bored a m103 (or similar) I would be interested in hearing their experiences and costs.

[Frank Reiner]

Originally Posted by eliburch

My 2 main goals here are low cost and reliability, not necessarily maximum horsepower.

Originally Posted by eliburch

Mo Powah Bebe. Wanting 300+"whp".

Begin with 350-360 V8 HP.

[sm. pelle]

If boosted engine is goal then just go with 2.6, your diriveline will explode before 2.6 reaches its limit.
For larger displacement u need om603 3.5 crank and custom pistons, in just boring there is no point, m103 doesent have enaugh cilinder wall.
And like mentioned before, 2.6 has smaller valves.

[eliburch]

Originally Posted by Frank Reiner

Begin with 350-360 V8 HP.

Once again not helpful or relevant to my question. I realize you think this is a bad idea. Thats totally fine. You don't need to keep posting.

[eliburch]

Originally Posted by sm. pelle

If boosted engine is goal then just go with 2.6, your diriveline will explode before 2.6 reaches its limit.
For larger displacement u need om603 3.5 crank and custom pistons, in just boring there is no point, m103 doesent have enaugh cilinder wall.
And like mentioned before, 2.6 has smaller valves.

I appreciate the advice. Do you have any idea if the 2.6 crank or 3.0 crank is stronger? I would guess they're almost the same.

As far as boring goes, the m103 has plenty of cylinder wall. AMG and Brabus bored the 3.0 to 3.6. I wouldn't bore it that far (especially if going turbo) but if AMG did it I'm sure its safe and I'm sure 3.2 would be fine for a turbo application.

[eliburch]

After some more research I guess AMG bored the 2.6 to 3.2 for installation in the W201, using the head from the 3.0L version for the larger valves. (according to username: MTI on this forum)

So maybe boring the 2.6 to 3.2 might be a little risky with forced induction...

[duxthe1]

Originally Posted by eliburch

Do you have any idea if the 2.6 crank or 3.0 crank is stronger?

They are the same crank and you'll NEVER break it.

Originally Posted by eliburch

As far as boring goes, the m103 has plenty of cylinder wall. AMG and Brabus bored the 3.0 to 3.6

Actually the 3.6's are frowned upon for boosting. Taking that much meat out of the bore has repercussions especially considering head gaskets are not a strong point for these engines to begin with.

Worrying about displacement is a bit of a moot point. Pick a turbo to efficiently make your target power then bolt it to something and run enough boost to hit the target.

[sm. pelle]

2.6 and 3.0 m103 are same, just bore and valves are different(early 3.0 should be also with smaller valves).
AMG got most of its displacement from strocking not boreing.
For 3.2 displacement with stock crank u need 92mm (3.5mm overbore) pistons (amg m104 had 91mm bore) and there are no meat between cylinders.
With Om603 3.5 cranck and stock 3.0 bore you'll get 3.4l, but that means custom pistons.

[eliburch]

Thanks for all the info guys!

I'm leaning towards just turboing the 2.6 and if it blows up just replacing it with a 3.0 since all the parts will fit the same and a used 3.0 can be found for half the price of custom pistons (or less).