Anyone know the typical differences in exhaust gas temperatures in naturally aspirated versus turbocharged diesels? I'm figuring there must be a higher average temperature in turbocharged engines, why else would piston oil cooling squirters be installed. But, I can't find any info on the web about the temperature differentials. Anyone have a pyro in an NA and a turbo that can provide some insight?
I've read in a number of places that EGT's above 1300 degrees for sustained periods in a turbocharged engine are bad for the engine, but that's with oil cooled pistons. What's a safe operating EGT temperature for an NA without oil cooled pistons?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

It's also going to depend on piston material for safe EGT (steel, aluminum, etc). I've heard that anything under 1100 degrees is safe and the 1300 is only safe for short times. Like you, I've never seen info on NA engines, I wonder if you can even get the EGT too high?

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k

I'm thinking about it because I'm considering purchasing a motorhome with a CAT 3208 naturally aspirated with an aftermarket turbo added to it. I'm trying to figure out if it is running at an acceptable EGT temperature since it has a pyrometer on it. It does not have the oil cooled pistons.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

A Cat engine may be totally different than a Mercedes engine. It might not use oil cooled pistons in the turbo model. You might have better luck asking this question on a Cat forum or a motorhome forum if they exist. I know that some ricer kids add an oil spray bar to their engines to squirt oil on the pistons to help keep them a little cooler. Something might exist for a Cat engine or Something might be adaptable to it.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png

The CAT does have oil cooled pistons on the turbo but not on the NA. I've talked to CAT about the differences.
It seems to me, at least in theory, that there should be an answer that applies in general to NA's and Turbo's regardless of the mfg.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The melting point of aluminium is 933.47 °K [or 660.32 °C (1220.58 °F)

I ended up buying the bus which led me to ask this question initially. I'll be monitoring EGT's closely over the next few months. But, I learned something in looking thru the CAT manual that came with it. CAT made turbo'd 3208's with piston oil squirters and without piston oil squirters. This is clear because there is a section on oil capacities which lists different oil capacities for turbo'd engines with and without oil squirters. I have no idea which hp engines were with and without or why the did it, but it does give serial numbers for each (which don't seem to coincide with any number on my engine).

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13