Here's a poser for someone out there who knows Mercedes!

I have a boat (it is a custom-built 40 ft. motorsailer for those who are curious.) I believe the engine in it is a 220D/8, perhaps 1971 but I'm not sure. A friend and I have searched for an engine number without success but looking at the old Clymer book it appears to be that engine. The original builder is now deceased, and left few documents.

As part of my refit I have to replace the exhaust system on the engine. (The new system will be a water-jacketed dry exhaust, all stainless.) To do this properly, my exhaust folks would like to know the maximum airflow (CFM) and back pressure specs. At worst, I can use the existing system as a pattern and go with the same diameter but that's not ideal.

Can anyone give me a good guess, or suggest who to contact? Thanks in advance for any ideas, facts or other help.

Daimler-Benz also manufactured small "industrial" engines which have different engine characteristics than the automotive engines. You need to find the engine number to be sure of what you have. The industrial engines were not designed for varying rpms and do not rev as high as automotive engines did. They were used as pump, generator, marine and remote power sources.

Automotive flow specs aren't really applicable.

Thanks Mike,
I was told that the engine was originally a 'truck' engine but I don't have any solid evidence. I might end up having to get someone who knows old MB to come and see if they can find the numbers on the engine.

I'm glad to know that MB did make marine engines - I was not aware of that.

MB didn't make marine engines. They were adapted from other uses. Much like Perkins, Dorsetts and Dagenheim engines. Many small industrial engines are ideal for motosailor use.

Also, I don't know if it makes any difference, but the information on the boat that I do have says that max RPMs is 4200, and 'cruising' is 3000 RPM. That seems fairly high for an industrial engine.

That does seem a little high. You are going to have to find the engine number to be sure of what you have.

You might be better served finding an old Perkins and slipping it in there. Perkins were used in about everything, welders, generators, pumps, mixers. etc.. and the odds of finding parts/service in a remote location would be a lot better.

I have seen the truck engines you mention and they look like the 220D only much bigger.

A photo in a Clymer manual will not be a good compariason. You might contact a Freightliner dealer and see if they can help you with this since Freighliner is a part of DB.