Chioce between M103 & M104 - PeachParts Mercedes-Benz Forum

BAD300 · #1 05-26-2010, 04:50 PM

Have located an M103 engine from a Sydney warehouse (Next state here in Aus). $950. Have asked the compression readings. think I'll give him a ring alter today & talk turkey. He also has an M104 for $1500. if this is a newer engine with lower klms & I know they have oil squirters in the block. This may be the better deal? Not sure about engine mount location etc? Anyone know if these blocks are same same?

Are the M104 engines a better choice? Considering it is to be turbocharged?

Also pulled the forged pistons fro the original engine. Only travelled 3-4k & look standard bore size

JamesDean · #2 05-26-2010, 06:28 PM

The M104 is a DOHC 6-cylinder.

As far as I know it should have the same mounting positions as the M103. Its a popular swap on 190E's. Usually just bolts right in (at least on the M103 based 190E's)

The M104 (unless really early ones) has a different fuel management system than the M103.

#3 05-27-2010, 07:40 AM

Yes the M104 can be bolted in place, but you will need LOTS of stuff from the donor car to make it work in place of an M103. It is a much different fuel injection system.

Is the engine currently in your car not rebuildable?

RBYCC · #4 05-27-2010, 02:26 PM

Quote:

Originally Posted by BAD300

Have located an M103 engine from a Sydney warehouse (Next state here in Aus). $950. Have asked the compression readings. think I'll give him a ring alter today & talk turkey. He also has an M104 for $1500. if this is a newer engine with lower klms & I know they have oil squirters in the block. This may be the better deal? Not sure about engine mount location etc? Anyone know if these blocks are same same?

Are the M104 engines a better choice? Considering it is to be turbocharged?

Also pulled the forged pistons fro the original engine. Only travelled 3-4k & look standard bore size

If you intend to turbocharge the better choice would be the M103-12V.
The M103-12V has a CR about 1 point lower then the M104-24V.
The lower CR lends to adding boost with less chance of detonation.

My opinion ( from experience ) is that the M103 is more bullet proof when boosted then the M104-24V.

The M103-12V power can be doubled from stock if set up properly at 7lbs boost.
I dyno ( Mustang load dyno ) at 262RWP and 302 torque.
Baseline pulls were 135RWP and 145 torque.
Published at the flywheel is 177HP and 188 torque.
So extrapolating I'm about 344HP and 392 torque at the flywheel at 7lbs boost.

The M104-24V was saddled with a bit more emission control parts which just aren't necessary if you're adding boost.

I prefer the CIS-E over the HFM and the M103 intake configuration over the plastic M104 runners.

However you decide make sure you do not only a compression test, but also a leak down test.
Don't necessarily look at the net psi readings on the compression test, but more the variance between cylinders.

BAD300 · #5 05-27-2010, 03:18 PM

Thanks heaps guys.

I should've mentioned that the CIS has been completely disabled due to running straight LPG with MSD ignition/timing control so emissions & fuel management is not an issue.

The original engine is cactus due to severe electrolosis damage etc.

CR isn't an issue if I rebuild it as I have forged lower CR pistons to use. Also. I am getting the inlet manifold customised to suit twin LPG converters/evaporators.

So, CIS issues aside. The M103 is still the better option? Or at least. Just as viable as the M104 for FI?

I was just considering the M104 due to the DOHC probably having lower mileage & more power than the M103? However if this is negligible then seems little point.

Also. I was going to have a custom made exhaust manifold made up to suit a single turbo but now due to workshop endlessly stuffing me around I want to do the fabrication myself. So, I'm now considering using a twin turbo set up fabricated similar to the set up that was offered by dealership new. This way I can utilise the original exhaust manifold set up & simply have pipework fabricated to suit.

I'll just have to see pics etc of the twin set up that was used.

RBYCC, All engines were comp' tested for individual readings. Workshop never did a leak down test to any of them due to the comp' readings failing the test. I will probably have head reco'd & timing chain, water pump etc all changed regardless.

BAD300 · #6 05-27-2010, 07:41 PM

Well phluck me deady.....have found an engine from an importer. Still in car. 180psi each pot. 124k's on it

That's almost as new!

If I give em the go-ahead. Will be ready to ship Wednesday!

Parramatta Prestige in Sydney??????

Think I'll go with it. There is only 1 engine

BAD300 · #7 05-27-2010, 08:28 PM

Just bought it! Arriving Wednesday

What I'm so rapped with is engine was still in 90 model pristine low klm car @ point of conversation (still is now) so compression readings are genuine

Now I can get serious with build format etc

RBYCC · #8 05-28-2010, 09:56 AM

Quote:

Originally Posted by BAD300

Well phluck me deady.....have found an engine from an importer. Still in car. 180psi each pot. 124k's on it

That's almost as new!

If I give em the go-ahead. Will be ready to ship Wednesday!

Parramatta Prestige in Sydney??????

Think I'll go with it. There is only 1 engine

180 is great..

If I recall my engine with 62K miles was 185 +/- !!!!