M104 Cylinder Head differences... - Page 14 - PeachParts Mercedes-Benz Forum

400Eric · #**196** 05-25-2010, 03:33 AM

MB rods are forged. I don't know where it got started that they are anything but forged.
Regards, Eric

Turbo E320 · #**197** 05-25-2010, 04:11 AM

I don't know what it is about the 16v's but the rods look the same as the 104 but I've seen two blown up 16v's. Both with snapped and bent rods and they were not boosted, not even modified. My m104 went through 25k miles of boost ranging from 8 to 20 psi, mostly 11-13psi, and the rods look new.

Joreto · #**198** 05-25-2010, 05:37 AM

400Eric, that interesting ! I remember reading in some repair manual that the stock rods were cast steel.

Turbo E320, my 16v also handled 14+ psi with no problem, but the rod broke because of a seized wastegate (on a 1/4 mile run) so boost was probably pretty high..but fact is that the rod when before anything else (i.e. pistons). Anyway I hope that the stock rods (from what I know m103 are like m104 rods) are strong since I've upped the boost to 15 psi on my m103

, hope six rods handle power better than four

.

P.S. actually I've two boost settings 0.5 (~7.35 psi) daily driving and ~1.0 bar (15psi) when a want more fun (turned on by a switch)

400Eric · #**199** 05-25-2010, 06:55 AM

I think 16v rods are already highly stressed before we ever even get those cars because they tend to owned by folks who wind the pee out of them. That may be why those rods fail so often.

The 3.0 and 3.2 M104s do have the same rod as the 8 valve M102 and M103 but one thing I do not know is if the 16 valve got that same rod. Could you guys enlighten me?
Regards, Eric

Joreto · #**200** 05-25-2010, 07:12 AM

I think the 2.3-16v has the same rod, while the 2.5-16v has different c-c length .

P.S. From what I've learned the c-c length for the 2.5-16v is ~149mm and ~ 145mm for the 2.3-16v. Looks like the difference is that some very early rods (upto 1984 ??)had a 24mm width compared to 22mm with of the later ones

JayRash · #**201** 05-25-2010, 03:17 PM

well roman claims that the M103 internals can live with 500 hp! i for one can say that 400hp is safe on the internals, if thy arre in good shape, but at this pwr any mistake in the tune will burst any internals. on my M103 the ring broke but non of the internals suffered any damage @abt 11 psi and a bad tune, internals had 390000km+ on them. AND i ended using them in the rebuild (rods and pistons)

MAG58 · #**202** 05-25-2010, 04:57 PM

You guys are forgetting one major thing between 16v cars and the M103/4. Piston size. 88.5mm in the 3.0L cars, 89.9mm in the 3.2L cars and 95.5mm in the M102's. That's a big difference there. If you notice, from what I've seen on the 16v failures, it's in the center of the beam. That's not a common break from compression, usually you'll see them break at the extremes of the rod near the large end or the small end. This suggests that the extra weight of a piston that's between 5 and 7mm larger in diameter causes the break under tension.

Remember that the compression itself usually does not cause the break but rather the transition at the top or bottom of the cylinder in the change from tension to compression or vise versa that will kill a rod. I've never held a 4cyl piston, but the .98 M104 pistons aren't that weighty for a cast piston and the gutted a bunch out for the .94/.99 pistons which is probably why roman doesn't feel the later 104's are as stout.

M104's are stout little motors, but even like the "legendary" (I hate that term, oh so very much) 2JZ, when you push one and cause detonation, it'll shatter a ring land just like any other motor will.

Just remember that it's usually rev's and piston acceleration, not horsepower, that usually breaks rods. There's a reason that people don't recommend spinning any motor 10krpms and even those that do, don't see their motor lasting forever.

I'll also be willing to bet that a 2.8L M104 will last the longest even at high hp since it can spin higher safely due to a lesser piston acceleration at TDC and BDC.

400Eric · #**203** 05-26-2010, 06:05 AM

Quote:

Originally Posted by 400Eric

I think 16v rods are already highly stressed before we ever even get those cars because they tend to owned by folks who wind the pee out of them. That may be why those rods fail so often.

I'm not forgetting that the 2.3 and 2.5 M102s have a bigger, heavier piston but it wouldn't be an issue if people didn't wind the pee out of them.

I agree with everything you said in your post except for three things:
1) It's RPM not RPMs. You are counting the revolutions per minute not minutes.
2) It's engine not motor.

3)There are some exceptions as to what makes rods fail. Here are the rods from a mid 12 second turbo Volvo:

We are still trying to figure out why all 4 of the rods from this engine are bent and yet the stock, cast pistons are fine. Whatever was strong enough to hurt the rods should have hurt the pistons too. Honestly, I'd love to have a bright, sharp, insightful kid like you weigh in on the topic over there on the Volvo site: http://forums.turbobricks.com/showthread.php?t=204800&page=2

So the 2.5 16v also has 149mm rods? It's funny how ALL MB con rods seem to be either 145mm or 149mm long.
Regards, Eric

Joreto · #**204** 05-26-2010, 08:29 AM

I think I've posted this picture before but here is the broken conrod and like in the volvo the pistons are fine (well except the one on the broken rod). As I posted before damage is due to a seized wastgate (set at 1.4 bars) at a 1/4 mile run so god only knows how high the boost went . BTW the 2.5-16v pistons are not forged like the 2.3-16v ones .

kynsi · #**205** 05-29-2010, 12:36 PM

Quote:

Originally Posted by 400Eric

I'm not forgetting that the 2.3 and 2.5 M102s have a bigger, heavier piston but it wouldn't be an issue if people didn't wind the pee out of them.

I agree with everything you said in your post except for three things:
1) It's RPM not RPMs. You are counting the revolutions per minute not minutes.
2) It's engine not motor.

3)There are some exceptions as to what makes rods fail. Here are the rods from a mid 12 second turbo Volvo:

We are still trying to figure out why all 4 of the rods from this engine are bent and yet the stock, cast pistons are fine. Whatever was strong enough to hurt the rods should have hurt the pistons too. Honestly, I'd love to have a bright, sharp, insightful kid like you weigh in on the topic over there on the Volvo site: http://forums.turbobricks.com/showthread.php?t=204800&page=2

So the 2.5 16v also has 149mm rods? It's funny how ALL MB con rods seem to be either 145mm or 149mm long.
Regards, Eric

Looks like very much same internals, that I have in my M104. Only my rods are shorter and pistons are little different....

jovani · #**206** 06-08-2010, 05:19 PM

Any news about the flowtest....?

400Eric · #**207** 08-20-2010, 05:36 AM

Quote:

Originally Posted by MAG58

Back to the topic at hand...

I just recently pulled a 104.990 out of a 1993 300SE (build date 11/92).

1.) It has EFI, but no plastic mani or two part manifold. The block doesn't even have the bosses for the lower manifold. It has an aluminum manifold much like the CIS mani, but setup for EFI and throttle by wire. The MAF sensor is bolted directly to the top of the TB, not on the other side across the top like the later models. It has the early model valve cover and the air filter looks the same as the CIS motors. The Injectors themselves are not the thin saturated EV1 style injectors on the later motors, but rather are shorter and fat, appear to be the same in color and markings as the S500 injectors from the same year.

2.) It has the new style head, and looks pretty much like the later style heads on the intake, but has more meat around the ports. It is also sealed by one metal gasket much like the .98 motors, instead of the o-rings found on the other 3.2's.

3.) It has a distributor on the front exhaust cam much like the .98's.

4.) It appears to have both the webbing from the .98 and the newer .94/.99, not one of the other.

I haven't had time to rip into the block itself yet, but I'm really interested. I'm pretty sure the head has the dual slider setup on the timing chain as opposed to the idler gear that the .98 has since it has the water outlet out the front like the later models and not out the side as the .98 was.

Has anyone seen this particular motor before? I have no information on it in my 104 FSM's as there doesn't seem to be an intermediate period between the two. Mercedes makes it seem like an abrupt switch over. ?

I recently encountered one of these engines in a 93 W140 at my U-Pull-It too. It has a LH fuel injection system much like the one on the same period M119 W140s and W124s. Apparently, the HFM M104s were the next evolution and the W124s just happened to get that set-up first much like how the W124s got the LH set-up on their M119s 2 years before the R129s did. (R129 M119s stayed with CIS 2 years longer.)

This opens up a neat possibility. A 92 LH M104 set up would have WOT fuel enrichment which is something that none of the 93 and later M104s have. (Or ANY 93 and later MBs for that matter.) I'll bet if we look up the power ratings we will find the 92 M104 had one of the highest power ratings of any of the M104s. While I don't think the power difference would be enough to make switching systems worth the trouble, I do think that guys (coughMAG58cough) who are starting from scratch swapping an M104 into an engine bay where it wasn't originally placed, who are trying to stick with a factory F.I. system, would do well to use a 92 LH version M104. (Maybe with the later "active" intake adapted to work. What a combo that would be! Probably not necessary if the engine is to be boosted though.)
Regards, Eric

JayRash · #**208** 08-20-2010, 06:32 AM

the W140 3.0 m104 did make a sweet 231 hp but at slightly lower rpm than its CIS bro
and rev limit was also lower.

400Eric · #**209** 08-20-2010, 08:18 AM

I would have sworn this engine that I saw was a 3.2.
MAG, what was/is the displacement of the 93 W140 engine that you grabbed? Remember, the fact that it was called a "300SE" doesn't mean much as my M119 W124 is called a "400E" even though it's engine is actually a 4.2.
Regards, Eric