On the OM603 and OM617's, do you know what the actual average psi backpressure is in the exhaust manifold?

When I have the manifold off to drill/tap for a pyrometer I also want to drill/tap a fitting for a pressure gauge to see what really affects pressure (rpm/load/exhaust/boost/temp).

I know to use copper tubing for a few feet after the fitting, but will the gauge feel any real temps, say with 3-4 feet of tubing?

Your question will better be answered in the Finnish MB-forum English section. Mauri is the moderator and reads it daily.

http://mersuforum.net/forum/viewforum.php?f=29&sid=f351bc930b19316a06382d5030e92f2c

Well, I don't really know the pressures in standard engine, never measures it. But it shouldn't be any higher than the boost pressure. I have measured exhaust pressure from my recent engine, and for that used 3 ft oilhose and after that normal plastic hose. It was working ok for the two days I had the gauge attached.

I used industrial pressure gauge for that, and at least it had no problems with the heat. The hose wasn't even warm in the cabin. Of course in my setup the exhaust temperature isn't very high, at least not now in the wintertime, when I only use 1.4 bar maximum boost (20 PSI)

I don't have the exhaust pressure gauge on anymore, no need for that if you don't do any changes for the engine.