View Single Post
  #26  
Old 02-02-2011, 10:26 AM
C Sean Watts's Avatar
C Sean Watts C Sean Watts is offline
NOCH EIN PILS!!
 
Join Date: Mar 2006
Location: NC
Posts: 1,318
Quote:
Originally Posted by josha37 View Post
I feel like i got bashed for bringing up rpm...
Not at all...what the factory did, besides changing the head gasket, was lower the max limited RPM. That supports your idea. If we 'go with what we know' everything else is speculation. 1. 603 series was kind of rushed into production because they were in a 'we have the fastest diesel car' fight with Peugeot. Not all the R&D testing went into them that went into other engines. 2. The 3.5L was sold in USA/Canada 16 months before any other market as the .970. The others were .971 and 2 mostly in G models (W463) in South America, Africa on the open market and to NATO military commands. This was well into the time the factory knew about rod bending and the corrective changes were already in place and working. Turns out they are good for 4X4 use because they make good torque for their size. BUT, rod stress and strain do not go up in a linear way like RPM. Under some conditions they go up exponentially with RPM.

Regarding fuel...nowadays Cetane (promotes combustion under compression) and Octane (inhibits combustion under compression) are no longer true enumerations of the content chemicals. They are an 'equivalent index' of them. --see photo--

In Germany and other places, they DO NOT USE the same numbering/labeling system as in USA for either one....The square yellow label on the pumps show the formula "R+M/2 method" IE: the average of 'research' and 'motor' octane. That's always going to be lower than research octane only since research number assumes complete combustion and motor number is an actual 'run it in a motor on a test rig & listen for knock' test. What we see is 'regular = 91 research, midgrade = 95 research' *not shown or dispensed at this pump "super+plus" (premium) = 98 research' They do actually correspond to 87, 89 and 93 octane in US markets using R+M/2 and not just R.

As for diesel fuel...according to this at the time these these engines were being built, cetane was actually higher in the US market than in Europe. I have not found any confirmation or denial of this linked info as of now. EU minimum cetane of 38 in 1994 and 40 in 2000. US- minimum 40, testing in the 42-45 range. **NOTE** as of summer 2010 cetane rating is not required labeling on diesel dispensing pumps in Germany.

translation of photo
(gas1)
"This fuel complies with German Industrial Standard EN 228 regular sulfur free 91 research octane."
(gas2) same except "Mid-grade sulfur free 95 research octane" *again note, 'super' in Germany = 'mid-grade' in USA. and 'super+plus' in Germany = 'premium' in USA
(diesel)
"This fuel complies with German Industrial Standard 51 628 diesel fuel sulfur free."
(rectangle)
"Contains up to 7% biodiesel" I'm told by my bro-in-law it's about 2% during winter and about 5% during summer.


IMO...? (that and $7 gets a whatever designer coffee is fashionable these days) I think some bent rods were from oil, some from load on the rods at high RPM. I do not believe cetane or timing were factors because they both stayed the same AFTER the rod bending stopped.
Attached Thumbnails
Rod Bending ~ weak rods /poor fuel/ bad injector timing-boxes-132.jpg  
__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!
Reply With Quote