blown 944

All I can say is I hope whatever resolution you decide is that I want it to be a success.

There is an obvious inherent flaw in the oiling systems. I do think that the smaller bearings (also modern bearing materials) help to maintain integrity. The surface areail volume ratio is better.

Couple that with lighter parts it would seem to also be a benefit to bearing load.

I am not the only one who has done this. Henk's racing engine uses the same design.

The crank may have a substantial hardness from the factory, however, in these cases it doesn't seem to be helping out much.

After grinding you can have them nitrided and bring the surface hardness back up. Maybe not as deep but enough for a solid bearing surface.


I do my stuff inexpensively, but I will say that regardless of budget, I would use the smaller bearings.

Again this is not new tech, MM, along with other engine builders have been doing it for decades.

Not trying to argue, just relaying what I've learned through the process.

Duke, if you decided to scap your parts.. I would be interested although shipping would be prohibitive.

theedge

That groove is pretty spectacular.... Self lightening rotating assembly, better patent that

Otherwise that sucks though.

blade7

Offset grinding decreases the overlap between the main and big end journals and reduces the bearing area, having said that the crank is a very strong item to start with so it seems to be still all good.

blade7

??

Tedro951

Sid, did your budget build crank get welded before grinding? I was under the impression it was just offset ground, then nitrided.

blown 944

Just ground, no welding.

Duke

The missing metal goes up 35 mm into the cylinder.
Measuring from the deck down the cylinder the missing piece starts at 115 mm.

Duke

Castrol Edge 10w60 is pretty much the top tier of oil and the engine had been running for less then a seson so in my case there wasn't really any more I could have done to prevent this.

Duke

Regarding the stroker cranks. I'm sure it can be done correctly, but it's not really an apples to apples comparison with street cars and race cars than pull consistantly over 1.4G's cornering.
I'm sure this engine would have survived for tenth's of thousands of kilometers on the street.

blade7

I had a quick look at the spec on the Castrol Edge and I dont think it's a triple ester PAO blend, that and the lowish price makes me think you could do better.

Duke

Let's not turn this into another oil thread.. The Castrol 10w60 Edge is a decent oil. But nevermind, you're theorizing a bit too much, this failure was not related to the oil.

blade7

OK.

blown 944

Very true, however, I will get you the number to the guy who has done these cranks (small bearing) for a long time. You can ask him directly who he goes them for as I told him I wouldn't divulge that.

I can assure you you may change your view regarding race quality.

PM coming in the next couple hours.

Paulyy

Geez, looking at those pictures, i didn't expect the rod to fail and break like that. Probably have to look at those arrow Titanium rods.

Duke

No. This was not the rods fault. Titanium arrows would not have helped in any way