Is it possible to get the 3.5 603 up to around 275-300 hp the extra torque it makes would be real nice in a heavy car. Do they make stronger rods for it or should i forget that and use the 3.0 603. Are there any writups on swapping the 606 into a w140 chassis. I know the 606 is the best but if its a pain to get it to work id rather stick with the 603

Sounds like an exercise in futility.

You better make sure you have a VERY well sorted w140 worth the work before going after it.

Supposedly the factory refurbished engines had different/thicker rods, and could accumulate high miles without big issues. I have one of these and it runs beautifully.

The reason for beefing up the rods was not relevant to power though. It was related to some of the theorized reasons why rods bent.

These are heavy cars and this pretty slow with stock engines. Meanwhile they only return 26-27 mpg. Upping power will make it thirstier, not sure about that much faster. They sell v12 models if that’s the interest.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Yea i didnt think building the 3.5 would be worth it was just curious if it could be done reliably. Iv searched everywhere and i cant seem to find a good build thread of putting the 606 into the 140 if anyone knows where to find one i would greatly appreciate it

The 3.5 engine set up as delivered is structuraly weak. Adding stress by increasing power? To my knowledge I have never heard of one being attempted.

If you look at a picture of the 3 liter block and the 3.5 liter block with the heads off. You can see the problem instantly.

There is so little material left between the cylinders. It is pretty pathetic in comparison.

Years back a member did a Rockwell hardness test on the early 603 Mercedes heads. He found the harness of the material in the castings was all over the place.

Since some 3.5 engines lasted I also wondered if the quality of the 3.5 blocks was similar with poor material quality control.

You want to try a stunt like Mercedes did especially. Eliminating the cylinder liners as well. You had best go to a very high nickel content block casting.

I'm not sure about the W140. Looks exciting!

More info is available for the OM606, or 3.0 603.

Standard sites, which you probably already know, are Superturbodiesel and Diesel Pump UK and various Nordic superpump whizzes.

I guess, what is it you really want? Simple, complex, mechanical, electrical? What sound are you going for?

Either way, there are ways to go with mechanical or electrical pump setups that could get you to that number.

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1982 240d RHD OM605 & 5spd swap


1982 240D LHD/RHD & 300TD LHD / 1983 300SD LHD / 1986 300SDL LHD / 1992 300TD RHD / 1998 C250 TD RHD


www.repaircafeglasgow.org

I do like things that are simple but i also like luxury smooth driving cars. Which is why i was looking at the w140. Actually getting the hp i want is no big deal just a matter of pump, turbo, and intercooler its getting the engine i want thats the real deal. The om606 just seems to be the best engine there is, it has no head cracking problems the bottom ends are incredibly stout its just the best. For me mechanical is the only way to go i really dont like electronic engines.

So far from what im able to find the 606 will bolt to the original trans so that solves that. The 603 oil pan will bolt onto the 606 so if the 606 pan wont fit i can use the 603 pan so theres that. Im not 100% but i believe the 603 engine mounts work for the 606 and everything bolts up no problem. Seems i have to use the 603 oil filter housing on the 606 with a spacer so it will clear the manifold thatll allow me to keep cruise control. The power steering, alt, vacuum pump, ac compressor and all that all work and is not a problem from what i could find. The only things im not real sure on is which radiator hoses to use and the intercooler and piping. Is there intercooler pipes that will work or will it have to be custom. All this in reference to swapping the 606 into a w140

The W140 came with an OM606 in europe, so you need the intercooler from that. You also need the injection pump from a 3.0 OM603 (unless you are going to have it modified). The transmission should bolt up, but also isn't very strong. The 722.6 5 speed automatic would be better, but then you have to work out how to control it since it's all electronic. I have thought about doing this too, it seems like an OM606 powered W140 would be the best combination for a Mercedes diesel, but there are definitely issues to work out.

Searching around i cant seem to find the intercooler or piping from that car with that engine. What are the part numbers. Isnt the 722.3 a very strong trans i was thinking it should be able to be built to handle it without much problems

I have no idea on the part numbers, but it's from a 1996-98 S300 that was not sold in the USA. The 722.3 isn't bad, but being good enough for a V8 w126 is different than a w140 with a 300+ hp diesel.