Why did MB design the 616/617 with a non-crossflow head? - PeachParts Mercedes-Benz Forum

Flounder · #1 09-05-2008, 08:20 PM

I've been wondering about this. By the mid-60's almost all the cars I can remember, even crappy ones, had crossflow heads. Why didn't Mercedes make the 61X engines crossflow?

With a diesel does non-crossflow have some advantage? The only reason I can come up with is it makes maintenance easier since they put the injectors and GP's on the opposite side to the manifolds. Maybe since they were targeting the taxi market ease of maintenance won out over performance.

What do you guys and girls think?

dkveuro · #2 09-05-2008, 08:47 PM

http://en.wikipedia.org/wiki/Reverse-flow_cylinder_head

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pawoSD · #3 09-05-2008, 09:53 PM

Quote:

Originally Posted by dkveuro

http://en.wikipedia.org/wiki/Reverse-flow_cylinder_head

.

Very interesting.

I love reading that stuff.

#4 09-05-2008, 10:34 PM

The OM61x series was basically a modified version of the engines thay had been using for decades. It wasn't until the 1984 OM601 that MB made a complete redesign of the engine.

compu_85 · #5 09-06-2008, 12:37 AM

Quote:

Originally Posted by Flounder

...By the mid-60's almost all the cars I can remember, even crappy ones, had crossflow heads.

VW didn't put a crossflow head on their "normal" gas engine until 1993. The TDI wasn't crossflow until... now! The upcoming 2.0 common rail is crossflow... and looks like much more of a bear to work on.

-Jason

#6 09-06-2008, 12:45 AM

The VW 2.0L PD engine was crossflow several years ago.

pawoSD · #7 09-06-2008, 12:50 AM

Quote:

Originally Posted by ForcedInduction

The OM61x series was basically a modified version of the engines thay had been using for decades. It wasn't until the 1984 OM601 that MB made a complete redesign of the engine.

Yep, they're just the smaller slightly evolved offspring of the U-boat diesels....

U-300SD

t walgamuth · #8 09-06-2008, 05:37 AM

A non cross flow head was a big improvement over the side valve it replaced.

State of the art when it was designed. Truthfully in diesel It probably does not make much difference since the valves are straight up and down.

Tom W

turbobenz · #9 09-06-2008, 05:59 AM

Quote:

Originally Posted by t walgamuth

A non cross flow head was a big improvement over the side valve it replaced.

State of the art when it was designed. Truthfully in diesel It probably does not make much difference since the valves are straight up and down.

Tom W

especially on a FI engine

WD8CDH · #10 09-08-2008, 01:03 PM

Probably because non-cross flow is so much easier to turbo so they didn't bother to change..

TimFreeh · #11 09-08-2008, 01:13 PM

Quote:

Originally Posted by ForcedInduction

The OM61x series was basically a modified version of the engines thay had been using for decades. It wasn't until the 1984 OM601 that MB made a complete redesign of the engine.

Exactly correct.

The "roots" of the OM61X series of engines trace directly back to the OM621 that was first installed in the 1959 190D.

pawoSD · #12 09-08-2008, 01:16 PM

Quote:

Originally Posted by TimFreeh

Exactly correct.

The "roots" of the OM61X series of engines trace directly back to the OM621 that was first installed in the 1959 190D.

And what did the OM621 descend from?

DieselClack · #13 09-08-2008, 03:00 PM

A reverse flow head at the time gave better performance and fuel economy than a crossflow head because it was a diesel. A crossflow head developes it's advantages at a high RPM, 5500 RPM and above, something you don't do to a Diesel any way!

A reverse flow head also made it easier to Turbocharge and it was much better for fuel economy and emissions.

TimFreeh · #14 09-08-2008, 03:54 PM

Quote:

Originally Posted by pawoSD

And what did the OM621 descend from?

The OM621 was a "clean sheet of paper" design - it was state of the art thinking... in 1957.

I'm not sure why you used the smiley icon? but the engine that preceeded the OM621 was the OM636, used in the 180D.