Ooh, this should be interesting - Jeremy recently sold an immaculate '85 300D so he knows very well the 123 engine bay. He has both an '87 300D and '96/7 E300 so he can directly compare 603-T and 606-NA.

But I have to agree with you. The NA 603 trades off nothing on the exhaust side for a manifold and air cleaner that hide the IP. I'll take the more balanced used of space in the turbo.

Sixto
87 300D

Okto, you make some interesting points with which I will find it hard to argue (but what the heck . . .). Yes, the I-6 engine hits the firewall but so does the I-5 in the W123 model 300D (but there's not much back there to work on anyway). My '85 300D (CA version) had a pretty busy engine compartment, especially on the exhaust side. At least the trap cat forced the turbo to be up where you can get at it; in the 124 chassis the 603's turbo is buried. Overall, comparing pictures of my '85 and '87 300Ds, both are crowded on the right side and roomy on the left side. Interestingly, my 606NA is the opposite.

The main advantage of the OM617 engine is that it has the air intake and exhaust on the right side, leaving the left side relatively uncluttered. In the 60x engines the IP is lost under the intake manifold and the glow plugs are similarly buried. The 606NA is quite clean on the exhaust side -- dropped tools on that side fall to the floor, or would if the belly pans were off -- but it's pretty crowded on the intake side, much more so than the 603 engine in the 124 chassis.

I suspect that the relative roominess of a 123 engine bay is a function of which engine is in it. I don't have a good mental picture of an NA 61x because I've seen so few but the 617 turbo in California trim is very crowded on the exhaust side, more open on the intake side. Either way, it seems to be a very "busy" engine with wires and hoses and linkages all over the place. The 60x engines just seem cleaner, making the engine compartment look less cluttered. Maybe that's what I really was thinking of when I said "crowded."

As for the relative reliability of the 606 vs the 603, it's mostly a matter of the alloy head learning curve at Daimler-Benz. The later 606 engine got all of the improvements that were gradually introduced in the various versions of the 603 head. Additionally, the 606NA engine is less stressed than the turbo 603. [Did Europeans and other who got 603NA engines have the same problems?] A 603 with a late-model head and head gasket should be just as reliable as a 606. Both are similarly vulnerable to overheating, I suspect. I haven't heard bad things about the 98-99 turbo 606 so they must have learned their lesson.

In any case, my preference for the 603 turbo over the 606NA is not so much for reliability as for performance and DIY-ability. The W210/OM606NA is much more electronic than the W124/OM603 turbo and the 98-99 turbo 606 is even worse. In California, '98-up diesels even have to be smogged (biannually)! One of the great joys of an older diesel is not having to smog it. The turbo 606 is even more powerful than the turbo 603, of course, but I've never driven one. It would be interesting to put a turbo 606 in a 1995 W124 chassis but I think the electronics are difficult to eliminate. Pity.

It's late. I'm tired. Good night.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

It is late. 617 intake and exhaust are on the same side I know you mean IP side.

You can get a good amount of turbo 606 benefit by running a turbo 603 IP and boost actuated wastegate. Throw in larger 6mm (or even 7mm?) IP elements and you're about there. The big problem then is plumbing an intercooler.

Sixto
87 300D

So from what you know, which is easier to get a few more hp out of?

Turbo engines for sure. There is a lot of conservative design so you don't blow the head off. You can probably reduce turbo 603 0-60 time by a second with an EGT gauge and tuning. The turbo 606 you can tune with a chip.

If 'a few more hp' is a goal, start with as much factory output as you can get - 17x hp with a turbo 606 or 14x hp with a turbo 603.

Start here - http://www.peachparts.com/shopforum/forumdisplay.php?f=100

Sixto
87 300D

Playing with the turbo 606 will require hacking the injection pump. Not easy and requires custom programming. Getting more horses out of any of these requires injection pump work which will run you $1000-2000USD. A suitable turbo and piping will run 5-700 more. I recently picked up a HY30W. It should provide 20psi and spool quicker than the stocker. Interestingly enough is has a t25 flange, I believe the t3 flange on the 603 and 617 motors is complete overkill.

Of course then you will be upgrading the suspension and brakes. Suspension will more than likely need rebuilding anyways at this point.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Great points but if w123fanman really means a few hp, he'll hardly push the envelope of how a gasser stresses the same suspension, brakes, etc.

Sixto
87 300D

Sixto makes a valid point. The turbo engines have a lot of "enhancements" to make sure they don't blow up. A boost gauge and an EGT gauge are de rigeur for anyone wanting to "add a few HP." Winmutt also makes a good point -- there's no shortage of air, especially with a turbo to help it along, but stock engines run out of fuel quickly unless you play with the IP and that is expensive. (Bring back carburetors!)

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I've driven busses and trucks too and yes, they have much better mirrors than a benz. But with a bus or truck turning your head to look is futile. The mirrors is all there is to check things out behind you.

In a benz you can turn your head and look in addition to checking the mirrors and when you look the blind spot is minimal. For a car the benz mirrors are better than most, IMHO.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

This had me irritated till I figured it out, too. Raise the hood to the all the way position.

__________________
1985 300D-189k The 'UD', Ivory and Pinkamino
1979 300D-211k Dark Gray, Parchment
A 1980 Harley-~166k and
A 1994 Ford diesel pickup-349k and
A 1990 gasser Volvo wagon-145k

If we're talking about a W123 I consider them about average for the era. Compared to modern cars they're too small and have too little adjustment range; you can't adjust them out far enough to show you what you can't already see with the inside mirror. The passenger side mirror on mine is also flat, where a modern car would have a convex mirror.

Agreed that blind spots for head checks are minimal, though. They don't have the high, upward-sloping beltline that's common in cars now, so you've got acres of glass and an excellent view to the rear, especially in wagons.

__________________
1981 Mercedes 300TD, 1994 Honda Civic Del Sol
http://mefi.us/images/fuelly/smallsig-us/67195.pnghttp://mefi.us/images/fuelly/smallsig-us/103885.png

Maybe Phil can order a crate of Euro convex passenger side mirrors for you 123 folks. Euro mirrors don't have that "objects in the mirror" disclaimer. Convex driver side mirrors are available too.

Sixto
87 300D