Maybe Andy, maybe.

But if you have one to compare, you'll see the extra size of the centre bearing on phase 1 engines means that perhaps there is sufficient oil flow.

Why isn't no. 2 big end always going?
What about the centre main?
Anyone measured the oilways on all the mains and big ends?

Still going to get mine nitrided as a precaution.

Paul

 

sorry just felt a bit victimised, will stop taking things personally.

In japan most common big end failure is number 4, as it was on my engine.

If the centre oil feed was really the problem then there would be an equal number of number 2 and number 3 failures, but that isnt the case.

 

I don't know much about tuned Cossies, only that the performance gap between them, and the tuned Subaru's is getting ever closer.

What I do know, is that tuners such as Tony Rigoli use the stock Subaru crank in their big power engines. Some of these reputed to be well in excess of 700bhp.

I'm not certain if using the Cossie crank is fair comparison, given the engines race bred origins, but, maybe someone could tell me if the 500bhp + Cossies use a stock, or up rated crank ?

I do however agree with Adam. I'm sure that the short design will be far less prone to flex, let alone that it's bolted between two block halves.

I'd also agree with Andy. I certainly think that the oil ways could be better designed, but this can be addressed during an engine re-build, if you really want to go that far.

Mark.

 

AFAIK cossies do use the stock crank as it is already steel anyway. Saying that, Ive heard of very few std cast pinto crankshafts breaking anyway. Cosworth just seemed to go overboard, as the cossie crank is supposed to be a lot heavier than a pinto cast one.
Im no expert in the matter, but subaru cranks look good, if nuthin else...lol
Curious as to why japan would see more No 4 failures. Doesnt make sense that we see more 3 and they see more 4. Are we all talking about the same no3 and no4 ???

 

who says we see more number 3?

 

Andy,

The Boxer design is a pain in the neck.....

I'm sure you've spent as much time as I, thinking about how to shorten the pipework

Mark.

 

Paul,

If you are nitriding your crank be sure to check the clearances before and after - as I'm sure you will... but also check the flywheel threads and timing sprocket/pulley before its assembled.

Regarding thrust bearings, I've seen a Phase 1 block which had nearly 3mm of crank walk.... needless to say when opened up it wasn't pretty, even though it ran and sounded fine! Prodrive modify their group N blocks to accept a larger more robust center thrust bearing.

 

Well, in my personal experience, I know of over 15 failed engines with all No3 big end going, plus those I have seen mentioned here.
That doesnt include melted pistons etc, only big end failures.
Most of these were STI v4, as i got the pistons from these engines, or got them for others.

 

Stevie,

that is prefectly fair,

It is possible that the problem with uk cars only shows itself with respect to number three because of differences between hte uk and japan, such as temperature or ron rating of fuel.

Ie. number 3 fuel supply may be compromised by fuel rail design, and this only results in failure due to lean running, which could be emphasized by the ron rating difference, and promote propensity to det.

who knows?

What I do know, is if the fault were due to the design for the oil supply to number 3, then surely number 2 would suffer more?

Unless some dodgy factor exists which means it is more difficult for the oil to reach number 3 than number 2, such as a strange g force anomoly, or something linked to the engine rpm or acceleration of the car which affects number 3 more than number 2.

I really dont know.