Does anyone know approximately how fast the engine is turning in a 617 in a 1981 300D at 85mph?

Really really fast... seriously. I don't think I ever got my '81 up to 85 mph, she screamed so much at 70 I just wouldn't push it. If I remember @ 70 she was already pushing 3500-3700 rpms.

I drive mine regularly on a stretch of interstate between 78-85mph. That is just staying with traffic. Does not seem to bother the faithful old girl.

MERCEDES-BENZ 300 D
as offered for 1981 until August in North America U.S.

1000rpm speed:
(km/h/mph)
I: 8.8 / 5.5
II: 14.6 / 9.1
III: 24 / 14.9
IV: 35 / 21.8
V: /
VI: /
Torque converter factor:
Final drive ratio std: 3.46

21.8mph @ 1000rpm = 3900rpm @ 85mph


Speed range (max speed on gears, top gear value theor.):
(km/h/mph)
I: 41 / 25
II: 68 / 42
III: 111 / 69
IV: 163 / 101

Notice how the top gear max. speed is theoretical.

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

I'd have no issues hitting 85 in my 79TD... aside from the NOISE it didn't seem to bother the car. well below the redline for the motor of 5500RPM or so.
gear ratio alone, along with stock tires puts the RPM's around 3800, toss in a bit of slippage from the TC, in an automatic trans and you get only 4000 rpm... plenty of room to go faster... assuming it's downhill, or drafting someone... I don't think the motor has the HP to push too much faster in wind or against gravity... I think my wagon topped out about 94 or so...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

At what rpm's does it start cutting into the fuel efficiency or is it mainly the wind resistance of the higher speed? The gearing on my 201 is pretty low such that 70 mph is slightly over 3400 rpm's. The car appears to handle it with no problems with plenty of pedal left to go much faster, but it sure sounds wound up fairly tight compared the the gassers with OD turning 2300 rpm's at 70.

__________________
You can't always get what you want, but if you try sometime you just might find you get what you need.

Running at this speed I have had several tanks at 26.2-26.7mpg. However, now that the winterized fuel is out it has dropped to 24.8-25.6mpg. A few years ago I used to buy 100% commercial biodiesel that was locally available for a period. I would like try that on this trip. She is a little loud at these speeds, yet she drives GREAT. How I love the ride and handling of a W123.

Thank you, Greg.