Pagoda SL Group

W113 Pagoda SL Group => General Discussion => Topic started by: n/a on December 22, 2006, 10:32:19

Title: typical rpm range
Post by: n/a on December 22, 2006, 10:32:19

In what range should the rpm's be in my '71 280SL when cruising at 50 mph?  Thanks for the info.

Title: Re: typical rpm range
Post by: jeffc280sl on December 22, 2006, 10:40:27

Maybe 2600 rpms

This should help


http://wahiduddin.net/calc/calc_speed_rpm.htm
or
http://www.4crawler.com/4x4/4LoCalc.shtml#SpeedoConverter

Jeff C.
1970 280SL 4-speed

Title: Re: typical rpm range
Post by: n/a on December 22, 2006, 10:47:41

Thanks Jeff

Title: Re: typical rpm range
Post by: ted280sl on December 22, 2006, 14:14:50

I believe there are some variables to consider in answering this question. Automatic or standard. If standard, 4 speed or the rare 5 speed. Which rear end is installed. The Euro models had a smaller rear end and therefore lower RPM's at highway speeds.
  I hate to confuse the issue but, I thought this information would help.
Regards,
Ted 280SL w/ 4 speed and Euro rear end

Title: Re: typical rpm range
Post by: Abbas on December 23, 2006, 03:18:30

Ted,
  I wonder why the Euro models had a smaller ratio and lower RPM than US version. Does this have to do with regulation or .... it is quite interesting to know. Actually, the high RPM is quite anoying some times - you feel that the car is making a huge effort and quite noisy/furious  :) .

Abbas

280SL W113 1969 Ivory
E280 W124 1995 Silver

Title: Re: typical rpm range
Post by: n/a on December 23, 2006, 09:15:36

U.S. model, 4 speed automatic - Jeff's number of app. 2600 rpm is right about what I am seeing

Title: Re: typical rpm range
Post by: Klaus on December 23, 2006, 09:29:58

Abbas,
regulations are involved inasmuch as the US always had lower speed limits. Therefore, engineering and marketing concurred that European models had to have a high top speed (200 kmh was the design target), while US models had to have better acceleration.

Klaus
1969 280 SL

Title: Re: typical rpm range
Post by: Abbas on December 24, 2006, 01:01:11

Abbas,
regulations are involved inasmuch as the US always had lower speed limits. Therefore, engineering and marketing concurred that European models had to have a high top speed (200 kmh was the design target), while US models had to have better acceleration.

Klaus


Klaus, from this I would understand that MB on purpose made the US version cars with higher ratio so that people cannot drive them at higher speed. Can this be changed by tuning the car or we have to change the whole differential.

Abbas

280SL W113 1969 Ivory
E280 W124 1995 Silver

Title: Re: typical rpm range
Post by: jeffc280sl on December 24, 2006, 07:26:06

Abbas,

I've recently changed out my rear axle in favor of an axle from a 1972 280SE 4.5.  The V8 Mercedes had a 3.27 ratio rear axle.  Do a search on this subject and you will find a lot of information.

Jeff C.
1970 280SL 4-speed

Title: Re: typical rpm range
Post by: George Davis on December 24, 2006, 12:53:51

I think the gearing in the US was market-driven.  US drivers were used to big, torquey V-8 motors that accelerate quickly.  The lower gearing gives the car somewhat better acceleration.

George Davis
'69 280 SL Euro manual

Title: Re: typical rpm range
Post by: Cees Klumper on December 25, 2006, 00:33:58

I changed my differential over from 4.08 to 3.69. There is obviously a difference, however it is not that significant. On the highway, the car still revs much higher than one would expect a six-cylinder to do. Converting all the way to a 3.27 would help somewhat more, however as noted the acceleration would suffer appreciably. I have just gotten used to the fact that this engine actually likes to rev high.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic