Your RPM's at cruising speeds? 300e/e320.

[bc2885]

At say 70-75 mph, what does your 300e/e320 read out for rpm's? My new 300e reads at what i think to be a little high at 3000-3200 rpm. Does this seem normal to you? Most of my prior cars have been V8's and they dont rev this high.
p.s. my 300e is a 1991.

[imon_2nd]

[8D]
My 1993 300CE CV has a 24-valve 3.2 liter motor, so it may be a slightly different than yours. At 3,000 RPM, the speedo says 80 MPH. I think that is within a few percent of accurate, as the tires are the stock size.

[bc2885]

Yes indeed. at 75mph, im at 3100rpm. Antbody else? I think w/ the old 4 speed automatic these will rev slightly higher?

[kungfu]

Yeap,
same here, 3000 rpm at 70 mph on a '92 300E. It makes me wonder since most traffic in interstates is going 80 these days, if this car is even able to keep up. On long trips, can it maintain 80 or 85, I would be afraid to burn it. Hope somebody can give us some info.

[jcmbz]

I am surprised coz my old 230E (in HK) rev at 3500 at 80mph... expect that 300E the engine should rev less... say 2500

my 560SEL engine rev at 3000rpm when travel at 80mph...hmmm....

[bc2885]

The car should have an extra gear, but doesnt. My w208 clk 430 revs extremely low at 75 mph. it is a 5 speed though. It seems a little more taxing on an engine than id prefer it to be, but it is what it is.

[imon_2nd]

[8D]
I took a closer look at RPM vs. speed, driving to work on the Interstate today. At 3,000 RPM it looks like 77 or 78 MPH.

BTW, an easy way to lower engine RPMs is to mount 'taller' tires on your existing wheels or go to larger diameter wheels and tires. Of course, you'll have to recalibrate your speedometer too.

[EuroCoupe]

The two main things that cause this is the 4 speed tranny and the gear ratio on the differential. The factory gears on the 300E are 3.07, the wagons have 3.27 so they will rev even higher at cruising speeds. A customer with a 300E came into my father-in-law's shop 2 weeks ago saying he had a tranny problem because he was pushing nearly 4000 rpm on the freeway and thought 4th gear wasn't engaging. After looking at the car we figured out it was fitted with a 3.67 differential! Great for acceleration but deadly for gas mileage. Bottom line, these motors can run and were made to run ALL DAY at 3000-3500 rpm. No worries, just keep an eye on temp gauge to make sure all is well. Or go to a longer gear ratio like a 2.87.

[bc2885]

Euro coupe, where would/can one find a shorter gear raitio rear end for a 124?. Can one out of another model work.

[kungfu]

I understood a shorter gear ratio will give you better accelaration but higher RPM on the highway, to lower it a taller ratio is needed. Either way, how do we change the ratio?