How many RPM's on your car at 70 MPH?
 

I took my GPS out for a little road trip on the freeway & measured different RPM's at different speeds in my 1985 300SD (also found out my speedo is reading REALLY slow. When it say's 65, I'm doing 75.)

At 70 MPH, I was turning 3,000 RPM's
At 75 MPH, I was turning about 3200 RPM's.

Just curious to know how many RPM's your diesel turns at 70 MPH in high gear & not accelerating. Year/Model/RPM's@ 70.

ie. 1985 300SD - 3,000@70

My 84 and 85 300 sd are both turning 3200 at 75. They will do this for longer than you can sit in the seat. Above 95 they both start to run hotter than I like after fifteen min or so but where can you run that fast for long anyway. Both do not have a hood pad but are quiet.

Good luck
Robert

same here.. mine reads 3200 at 75.

Same on the 81' 3200 @ 75

240D
 

Anybody with a 240D, manual transmission, stock differential and the oh-so-rare tachometer care to offer a datapoint for any speed/RPM combos in the different gears?!? One of these days I'm going to wire up a custom circuit to read a magnet on the flywheel, but till then...

Related question: where do most folks regard the powerband of a 616 engine to be?

Thanks,

Kurt

I usually cruise on the hwy around 60mph, and the tach is at 3000rpm.
My Bro in Law told me from time to time when he followed me, I was doing 70mph when I showed 60.

I would check the spedo/trip odo with the milage signs and where there is a spedo check. In 5 miles I was a about 3 or 4 10th slow.
have 205/70/14 tires with the stock 2:88 diff

I have had the spedo fixed twice in the past, and Iam thinking maybe they didn`t put the needle back on in the same position.

I have 3 spedos on the desk. When I lift the needle over the resting peg, spedo #1 rests right on the back side of the peg.
spedo #2 the needle in at the 6 o`clock position
#3 sits 1/2 way in between.
Iam thinking the spring on the shaft under the face maybe weaker on some than others.
Iam thinking about resetting the needle to see if I can get it to read correctly.

A couple months ago we went to Los Angeles area with my Bro in Law. he had his GPS, at 60mph, Iam doing 70mph @ 3000rpm.

Charlie

right at 3000 @ 70 in the 300SD
3200 @75

I did not like taking that car much over 75, it always felt like it was straining

the SDL is a different story

About 2600@70
3000 @ 80
under 4000 at 101

3000 or so at 70....3400 at 77.....which is my normal cruise speed.

My dad's runs about 2300 at 70....with a 2.47 diff. :D

I have my tires at 44psi, so there is probably a little less rolling resistance than most people have. :D And I've been getting 27mpg going 75-80mph.

85SD cruises all day at 80 & feels solid. Turns 3000 @ 70 which matches gps speed.

3000@70MPH

South of wound out, and north of lugging. It smokes black as you wind out (merging in 3rd at 50) and it can't get enough air through the manifold.

Mine had a funky tachometer screwed to the dash in front of the left speaker....ugggghhh. Removed it and plugged the screw holes. The pickup was clamped to the side of the alternator. I'm not sure how or why that worked, but an easy installation nonetheless. You might check into that if you're wanting to install a tach.

It also had a ammeter screwed to the bottom of the dash, took that off too. But then found out they had wired it in series from the alternator so I had no power whatsoever. Had to rebuild the harness and reconnect the alt to the starter. Nice learning experience.

On my trip across the country bringing it home, I had my handheld gps along, the speedo would read about 3-5mph fast. So at 67 or so indicated the gps said 62 and the tach about 3900. I didn't want to drive past 4000rpm for any length of time not knowing what service had recently been done, and it's winding out pretty good at that speed. At 70 indicated the gps said 65, and that was right about 4100.

With all the work I've done it cruises at 70-72 indicated without even breaking a sweat, doesn't even slow down for the hills now, and sounds smooth and sweet. Still wouldn't want to run it much faster than that though. It's spinning its little guts out. :P

3000@73mph. 83 SD. 16" Michelin Primacy tires. GPS confirmed.

3k- Right at 70-73. My speedo is a little off but close.

3000 rpm @70mph