Author Topic: How hard do you rev your old W116 straight six engine?  (Read 590 times)

BCDC

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How hard do you rev your old W116 straight six engine?
« on: 03 February 2020, 05:45 PM »
Hi All, I have been wondering how ofter people test their engines to high revs? My old Merc is 42 this year but i still give it it's head occasionally to between 4 and 5,000 RPM. I know these engines are well balanced and high revving but most of the time I use mine as a cruiser. I have heard the M110 engine has an ignition cut off at 6500 but I'm hesitant to test this. What do others do is what, I want to know and will these engines handle the high revolutions at times?
1978 280SE Cream with blue interior. With SLS

TJ 450

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Re: How hard do you rev your old W116 straight six engine?
« Reply #1 on: 04 February 2020, 01:02 AM »
When I had my 280S, it saw 7k rpm but then I sold it haha.

I did quite a few km in a W126 280SE and with just myself in the car I wasn't at all concerned about revving it out to 5k, occasionally to redline as this is where it performs well. With the car loaded up it would ping so it was then a case of driving gently.

I wouldn't be concerned about it going bang if it's running correctly.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

ptashek

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Re: How hard do you rev your old W116 straight six engine?
« Reply #2 on: 04 February 2020, 01:54 AM »
I've no rev counter in my 450SE, so can't tell exactly. But I've driven it for 14h straight only stoping for fuel, averaging just over 100km/h, in the past. It'll happily sit at Vmax if you can foot the bill ;)
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

Randys01

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Re: How hard do you rev your old W116 straight six engine?
« Reply #3 on: 04 February 2020, 11:20 PM »
Assuming she's untouched in 40 odd years and circa 250K kms I would limit max rpm to 500 less than beginning of red line. yeah when they were new you could rev them right out to cut-out or beyond if c/o  not fitted.
The last 500 rpm doesn't achieve too much  for all the throat strangling and out of respect for an unknown history and fair wear n tear we just don't bother.
In a worn motor the chances of stretching the rings a micron past the ring wear land  [coz its been redlined ] can crack the ring.
This is a known event within the jargon "ring float".

I only take my 6.9 past the red line in top gear.  lol!

Just as an aside, I once had a Renault R1134 Gordini [rare as now!] and  the tacho went to 8000 no red line. Yep every one in town took it to 8000 plus and when we pulled it down, the top ring groove was about 2mm wider than design! It did not crack  any rings because the thing had been hammered from day 1.
My current mover n shaker is an older Nissan GTR...redlined 8000 and cut out at 8. This motor is like new but I just don't want to screw the last gasp out of it............7500 is more than enuff to blow most opposition into the weeds..........






BCDC

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Re: How hard do you rev your old W116 straight six engine?
« Reply #4 on: 05 February 2020, 01:56 PM »
My car has only done 95,000KM's from new so not exactly a worn engine but still old I suppose. Even though the straight six 2.7L motor is so well engineered and balanced I don't think I will risk taking it above 5000 rpm very often. Not to forget also these things suck fuel at an alarming rate when driven hard. I live in a hilly area and rarely get better than 15L/KM.  My 36 year old Ducati would happily rev to 10,000 but with desmodromic valve actuation you can do it although it was sweetest at 5 to 7K rpm.
I can't imagine it is necessary to rev the old girl too hard to still have fun with these cars. It really is the total package that makes the W116 a great vehicle and driving it leisurely is a big part of it's charm. Still, I would like to hear from other owners to see if I'm being too conservative. Thanks for the replies so far.
 
1978 280SE Cream with blue interior. With SLS

TJ 450

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Re: How hard do you rev your old W116 straight six engine?
« Reply #5 on: 05 February 2020, 03:10 PM »
Yep, there's not a big difference in fuel economy between the M110 and the V8s under normal conditions. Even the 6.9 can achieve 15L per 100km or less in optimal conditions. Of course when driven hard consumption is significant with the V8s over the six.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500