Mercedes-Benz Forum banner

1 - 20 of 37 Posts

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #1
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.
 

·
Registered
2004 SL55 AMG
Joined
·
505 Posts
[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.
 

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #3
Yes indeed. at 75mph, im at 3100rpm. Antbody else? I think w/ the old 4 speed automatic these will rev slightly higher?
 

·
Registered
1992 300E
Joined
·
35 Posts
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.
 

·
Registered
111/123/124/126/140/201
Joined
·
925 Posts
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....
 

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #6
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.
 

·
Registered
2004 SL55 AMG
Joined
·
505 Posts
[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.
 

·
Registered
W126C AMG 6.0
Joined
·
846 Posts
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.
 

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #9
Euro coupe, where would/can one find a shorter gear raitio rear end for a 124?. Can one out of another model work.
 

·
Registered
1992 300E
Joined
·
35 Posts
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?
 

·
Registered
W126C AMG 6.0
Joined
·
846 Posts
Many 190E (W201) carriers will fit and they ranged from 2.87 to 3.27. The 16v 190E's have limited-slip 3.27 gears which would be best for performance. This 3.67 gear I mentioned is probably from a 300SE, W140, but I'm not positive. Check the ratios on the diesel W124 cars, I'm sure someone here has this info. Diesels generally have shorter gears since they are slow starters.
 

·
Registered
500E, E320, 190E, E55
Joined
·
1,006 Posts
3000 to 3500 revs. is not high by any means. My older 89' 300e with the 4 speed will run at 4600 to 5100 revs. with about 600 revs. to spare for long distances and never break a sweat (run hot) This translates to 115 to 125 mph. The only negative is increased oil consumption. In Europe and other parts of the world, these cars are are routinely driven flat out for long distances. Americans are used to driving lazy V8's and get excited when revs exceed 4,000 rpms or more than 100 mph. These are not Buicks yall.
 

·
Registered
1994 E320
Joined
·
1,730 Posts
1987 300E; 108,000km. Here are my numbers (all are approximate, on 4th speed):

74km/h @ 2000 rpm
87km/h @ 2500 rpm
91km/h @ 3000 rpm
128km/h @ 3500 rpm
146km/h @ 4000 rpm
161km/h @ 4500 rpm
182km/h @ 5000 rpm

That's as fast as I dared to go tonight with the increased patrol presence on Saudi roads these days. The last four speeds are illegal on Saudi roads (maximum legal speed is 110km/h.)

Shady
 

·
Registered
1994 E320
Joined
·
1,730 Posts
BC & Kungfu,

In theory, you can fit any 124 differential on any other 124 - it's a bolt-off, bolt-on affair. If you get a differential from, say, a 200E, it will perfectly fit on a 300E. But the 200E's differential has a shorter ratio, which means snappier acceleration, but less (actual) speed (that is, with the same transmission.)
And by "actual" I mean your real speed as opposed to what the speedo indicates. In the case of this scenario, the speedo could be indicating, say, 115 km/h, but you could only actually be going at 100 km/h (your actual speed on the road.)
Tire size is another story. my car is riding on 205/65R15 94V tires, which are aproximately 1.3mm larger in diameter than the stock 195/65R15 tires. This means that my actual speed on the road is 1-2 percent higher that indicated by my speedo, so when my speedo is cruising at 100km/h, i'm actually doing 101 or 102km/h. In comparison to the 215/60R15 tires I had before, I did notice a slight "sluggishness" in acceleration, but I also got slightly better gas mileage on long(er) trips. Otherwise, the slightly taller tires have no effect whatsoever on gear ratios.

Hope this helps,
Shady
 

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #15
Thanks Shady and Redwood for your thoughts! Good reading. Redwood, great analogy on people in America not going over 100mph w/ their cars. How much oil consumption (crankcase) were you experiencing and was it with synthetic oils or conventional? bc
 

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #17
Shady...Your passion for MB cars shines through in every way!![:D] Thanks for the info.
p.s. does your speedo have us units in mph as well?
km/hr is confusing to some of us here in the states.
 

·
Registered
1994 E320
Joined
·
1,730 Posts
Thanks BC [:)]
No, my speedo (euro version) is only marked in kilometers.
One mile = 1.61 km.
So here are my numbers translated in miles:

74km/h (46 mph) @ 2000 rpm
87km/h (54 mph) @ 2500 rpm
109km/h (68 mph) @ 3000 rpm
128km/h (80 mph) @ 3500 rpm
146km/h (91 mph) @ 4000 rpm
161km/h (100 mph) @ 4500 rpm
182km/h (113 mph) @ 5000 rpm

Shady
 

·
Registered
SL320, 300e, 450SL
Joined
·
1,044 Posts
Discussion Starter #19
Thanks for the formula Shady! Now im officially broken in Km style[8D].
p.s. hows that repair coming along? keep us posted. bc
 
1 - 20 of 37 Posts
Top