E30 Zone

I am building a high comp m30b35. Probably going to go up to 12.5:1 comp ratio.

My first question is how strong are stock rods? I would like to use the stock rods with the custom pistons if I can. And if 12.5:1 is to much for them what can they handle?

Thanks for any help

Depends on how high the engine will Revv

Andrew

how much rev can the stock rods handle?

I have seen a few rods that have come through the side of the block I would uprate the bolts if nothing else.

yeah i plan on using all arp bolts, just trying to figure out if i will have to get rods made also which i would like not to even if i had to drop the comp ratio to 10.5:1

Are the rods on a M30 fitted with studs and not bolts?

Im not too sure on what the same limit of RPM on the stock rods is, so cant really say. But looking at their design i would not really like to puch them past 6500rpm.

Andrew

Yes nuts

Are they the same rod that is fitted to the m10 engine what can that rev to ?

Actually if i remember correctly its a bolt with a nut on the end?

Yes its used on the M10 engines also.

Andrew

I was told by Mr E that the stock M30 arn't too clever above 6k(although short bursts of 6.5k should be ok ?).

The Alpina B10 bottom end that i'm going to fit uses M5 rods which are supossed to be stronger and lighter, they use bolts to fasten the caps on rather than studs and nuts of the M30.

Because the M5 rods are longer you have to have a piston that has it's pin mounted higher up than the M30 piston.

The B10 had a C/R of 10.6:1 so i should have that sort of C/R once i'm done.

Nice pick ED

Here's another

Nice pick ED

Thanks

Alpina rods

They might be early Alpina rods ?

Infact arn't those pictures from Ebay ?

The fasteners are just the same as normal M30 rods.

OK, so what is the concensus here? When I am done with the motor it will probably only have maybe 50hp more than stock, can the stock rods handle that, it seems to me they would be able to?

I still have the ones from the m30 I'm rebuilding and they look to be in great shape but I could get new oem ones, since custom rods are pretty expensive I hoping to not have to use them.

It's sustained high revs or short burst of very high revs that kill them so don't go daft on the revs and a 50bhp gain should be OK

Infact arn't those pictures from Ebay ?

Yes.

The fasteners are just the same as normal M30 rods.

Yes but the rods are lighter then the standard ones.

Andy didnt your engine put a rod through the block? Was it because of the nuts and bolt or was it the rod that broke?

ed325i wrote:Andy didnt your engine put a rod through the block? Was it because of the nuts and bolt or was it the rod that broke?

It was some thing to do with the bearing running dry for some unidentified reason, that produced a LOT of heat and caused either the fasteners or the cap to fail and the bearing to melt.

You can see the metal looks discoloured with heat and the bearing melted plus one of the studs is AWOL

alpina specs are odd

the bi turbo m30 used standard rods, unlike the na B10 !!

i've been told on the bi turbo's the boost limit is 20-22psi with an over boost to 25psi