75 replies to this topic

[turboman]

has anyone here used bmw rods in a holden 6? what is there lengh compared to normal/starfire rods? what size are they on the big end and little end of rod compared to normal/starfire rods?

[AbsynthHatch]

Already been talked about on here, rod length was mentioned but can't remember, try google

[ozyozyozy]

pretty easy to find bmw rod lengths on google.
there is alot of differences between all the motors, even same type of motor euro vs US spec.
Pauter conrods has a list with dimensions on them.

[SA EH]

Yeah I have the m30 rods in mine. Standard bmw rods take some getting in there, from memory they ended up costing something like $1200 to make fit. The rods were narrowed, crank was widened, they had a heap of weight taken off, shotpeened, crack tested, side polished......don't think they'll break though!

[SA EH]

I totally hear you OJ, it went a bit like this...
I was a little "less informed" at the time when I heard you could fit bmw rods into Holden 6's, so working on beemers I thought it would be a good idea.
Ring the machine shop.
"Yeah we can fit bmw rods for you"..... And so they did.
Little did I know that it involved a shit load of work to them plus custom pistons to suit. Was never told this nor did I pick up hints along the way.
Would I do it again, no.
Am I glad they're in there, yes.
They weigh in less than a starfire rod and still a little more meat around the big end.
479g if my memory is correct....

[SA EH]

Standard m30 rods....

[SA EH]

Bmw m20 conrods....


Pretty sure the m20 rods are a little smaller & narrower in the big end than the m30 rods.

[SA EH]

Um.... If that's what you're into mate:)

[SA EH]

Quite possibly, the only reason I could put it down to, Germans are crazy.
M30 & m20 rods are the same length by the way, 135mm or 5.315".

[SA EH]

From memory the crank from the m20 rods, say a e30 325i, looks similar to a counterweighted blue motor crank. The crank from say a 535i e34 with the m30 rods has a lot less counter balance, think more red motor.
By the way I've never seen a bmw 6cyl throw a leg out the bed in my time... so they must know something.

[turboman]

I have learnt that the bmw rods are 12thou thicker big end width and small end needs to be bronze bushed to suit.

don't no why this would cost $1200

[SA EH]

Acid bath, shotpeened, crack tested, machined shoulders, narrowed & chamfered, "dick" removed, lighten/side polish, resize big ends.....
Just reading from my invoice.
Sorry don't forget widening crankshaft journals...

Edited by SA EH, 25 September 2016 - 04:56 PM.

[SA EH]

I'm bloody sure those crazy Germans know a thing or two about 6 cylinders

[SA EH]

Notice how the m3 went from straight 6 to v8 then back to straight 6. Yeah, that's right....

[warrenm]

Certainly a "chunky" looking rod.

[SA EH]

For sure Waz, it's like my old man over engineering everything, it'll never break!

[jd lj]

The previous owner of my car bought an engine from forum member "82911", on his way home from a track day at Wakefield he put a leg out the side and obviously that was the end of that engine. The previous owner then salvaged what he could from that engine and used the original block to rebuild another engine. I can't remember what rods westend performance used in my current engine. I've spoken to Greg (forum member 82911) a few times over the years and he told me that the engine he sold had BMW rods. None of this really means much but might be of interest to someone.

[LC-GTR-1969]

The previous owner of my car bought an engine from forum member "82911", on his way home from a track day at Wakefield he put a leg out the side and obviously that was the end of that engine. The previous owner then salvaged what he could from that engine and used the original block to rebuild another engine. I can't remember what rods westend performance used in my current engine. I've spoken to Greg (forum member 82911) a few times over the years and he told me that the engine he sold had BMW rods. None of this really means much but might be of interest to someone.

 

I could be wrong but I believe 90% of the time the real culprit for throwing a rod has to do with either poor or non-existent oil pressure, or poor bearing clearance. H-Beams could just as easily throw a leg should the above happen...