Indicated 65 mph at 3000 RPM engine speed.

1982 300D


Just curious to see if there is some correlation between models and/or model years on the overall drive train ratio. I tried to pick an RPM that wouldn't get anybody in TOO much trouble.

Would like to hear from other 300D and 300SD owners with 5-cylinder engines if they see the same above or something different. Might even be interesting to compare with the 6-cylinders.

Get your tachometer right on 3000 RPM, and tell us your indicated speed.

[ I disavow any liability you may incur in doing this test ]

That sounds about right. I haven't gone out and drivne the car to test it, but if my memory serves me, 70 mph is about 3200 rpms. I don't know if the gear ratio is different between the D's and SD's.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

My 300D is at 3400 rpm at 80 mph.

__________________
Jim

On the way to work this morning:

@ 3300 rpm, indicated speed is 70 mph and boost is 9.5 psi
@ 3000 rpm, indicated speed is 65 mph and boost is 6.5 psi
@ 2750 rpm, indicated speed is 60 mph and boost is 5 psi

I tried to take the measurements on level roads. I think the big jump in boost between 65 and 70 mph must be due to the aerodynamics, or lack of. I would try some of the higher speeds, but I think I need to tweak the wastegate some more. The wastegate opens about 10.5 psi. I have hit 11.5 psi going up a hill, but it was momentary.

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

My speed at 3000 is 70 give or take about 50 rpm, this is a 1985 300d which i've heard is geared a little differently.

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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

Mine too is roughly 70mph at 3000 give or take a few.

Very interesting to see the overall gear ratio was changed a bit with the 1985 300D.

Still hoping to hear from someone with an S-Class just for curiosity and comparison.

300SD owners? Later model 300D?

Ken

We might be forgetting that tire and wheel size will have a MAJOR effect on RPM at highway speed.

However, assuming the stock 14 inch wheels and OEM size tires, I think ~3000 RPM at 70 mph is normal.

74 indicated 72.1 actual (GPS) 4000 is right about 90.
3K is pretty much my favorite speed in the 65 and 70 mph zones of Michigan and upstate NY.

__________________
When I close my eyes, and inhale, I can smell No. 2.

That's on stock 14 inch tires....285K

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When I close my eyes, and inhale, I can smell No. 2.

Hey do you really have the last W126 300SD??? I am going to go as far as to say, my father may have ONE OF the last W210 E300D's to exist, a 1999 spec car with a build sheet dated May 21, 1999. The car was delivered in late June 1999 after being held up at the doc a few weeks! When my father bought her in late April, we had to change the build order from a silver E320 to a E300D... He was lucky to get one of these fine cars being the factory is closed in July???

My car, the 85, was built in Aug 1984, and was delivered to a "Kim's Jeweler's" in Ocean New Jersey the first week in October 1984. I did some history checks, and found the inspection tag. Also, my dealer was able to help me.

Anyway, I was just wondering... This is something that I am getting obsessed with knowing, build dates, shipping dates, pick up dates... Like those Corvette owners who know what the guy ate for breakfast the day their 67 Stingray left the factory with the wrong hood, I have a thing with Mercedes Benz.

Randall, I too like having as much history as possible. I had e-mailed MBUSA, inquiring about the original cost of my car. They surprised me by sending me a copy of the original dealer invoice for my car. My car was made in April '80, then in May of '80, put on the vessel Rigoletto to be shipped over to the U.S. The dealer bought the car from MB on June 6, 1980 (date of invoice) for a total cost of $26,835. The original MSRP was $33,473. Even the engine number is listed on the invoice, and it matches the number on the engine block. Also the invoice shows that Chemical Bank financed the car for the dealer which is/was located in Rockville Centre NY. I found it to be in upstate NY.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

I checked my '82 300SD, at 3000 rpm it registered 70 mph. It has stock 14 inch tires and rims and 276k miles.

With stock 14" wheels (205/75?) I got
~2800 rpm@70mph

I got these stock 15" 87's wheels(205/70) for ($250) from a junk yard two days ago, Now I get
~2900 rpm @70mph

my rpm sender is from a 81 300sd but it has white cap instead of black like the original one. I have no idea which reading is right.

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BJ

09 GL320 Bluetec 65K+
07 E320 Bluetec 43k+
05 Nissan Frontier NISMO 4X4 72K+


07 Kawasaki Vulcan 900 5k+ gone
87 300SDL 158k+ gone
91 300D 113k+ gone
83 300SD 220K+ gone
89 300E sold
87 190E sold
83 380SEL sold
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Good fellow:

Your RPM is similar because the overall profile of your tires is more or less the same, even though wheel size is different. If originally you had 195/60/14 and then switched to 225/40/18 (pretty dramatic change there), you would see a very significant change, as your final drive ratio is basically lowered.