how high is to high to rev the engines on diesels?

Not sure about your particular engine. The M617 5 cylinder turbo that I have has a 5000 rpm max speed, but the power peak is at 4350 rpm, so I see little point in going any higher.

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

Engines with electronic injection control won't go over 4600 -- the fuel shuts off.

On others, don't exceed 5000 rpm. Rods won't take the strain. This also means don't operate the engine faster than the max speed mark on the speedometer on long downgrades, too! The engine doesn't really have to be under high load to blow at excessive rpm!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I shift my 300SDL at 4500rpm all the time.. once I was going 60 or so, and I accidently put it in 2nd gear and the tach read 5500 or so RPM.. scared the hell out of me, but no ill effects from the engine (sounded good at that speed, too!).

i have the 6 cylinder turbo

300SD:

The only way you could get your engine to rev beyond about 4600 would be to downshift too many gears at too high a speed (as in going to second on the gearshift at 80). The electronic fuel control will shut the fuel off under power, limiting engine speed to 4600 rpm. Good thing, too, as this engine has mucho ponies -- for sure if it ran at full throttle you would blow it up -- I can't see it running out of horsepower! Anything under 5000 rpm is probably safe. I avoid very high revs for longevity -- there is more wear at high rpms.

The last time I floored the Volvo on an interstate entrance ramp and held it there, it would only generate about 4500 rpm, but that was before I got the turbo fixed.


Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!