Over the years we've heard a rumor that the cast iron ETA crankshaft was somehow inferior to the Forged Steel 524 Turbo
Diesel Crank. BMW used cast iron cranks in the following engines.
320/6 - 71mm stroke
323i - 76mm stroke
325e - 81mm stroke
325i/E30 - 75mm stroke
325i/E36/E46 - 75mm stroke
In our experience, the cast iron cranks used in Baby Six Engines are very reliable punctuated by the fact that we have never seen one break.
However, we have seen 4 Diesel cranks break. Two that we found in salvage yard engines, were broken in the middle. The other two were fatigued from hard racing 81mm Stroke Crankshafts
- 275 HP engines revving to 7500 rpms. After 65-75 hours running
vigorously, they cracked at the back of the 6th rod throw.
Diesels rattle and vibrate throughout their lives and the crankshafts
take a beating. Naturally, before we install a 524 Turbo
Diesel crank in an engine, we would check it for cracks. This
can be done by lifting the crank off the ground and striking
each one of the 12 counter weights with a large wrench (19 mm
or larger). It should ring like a bell. If it doesn't - check the rod
journal nearest the dead counter weight and look for a crack. A
dead ring indicates a junk crankshaft.
Although we do use the Diesel Crank, it is rare. Out of every
100 2900 engines we build, 99 have "e" cast cranks and 1 a
Diesel Crank, typically per the customer's request. Nice advantages
are that the "e" cast crank is readily available, far more
economical, and it is 3.5 lbs. lighter - 50.5 lbs "e" vs. 54 lbs. for
the Diesel.
By using our lightweight pistons and limiting the engine output
to 225 HP and 6750 rpm, I see no reason why anyone would
see an "e" crank break.
http://www.metricmechanic.com/
http://www.metricmechanic.com/pdfs/M20_ ... ochure.pdf
siia teemasse, e30clubis on vähe inimesi kes oskaks vastata..)
