BHP

[mirafioriman]

As far as I'm aware the 2 litre twin cam has a steel crank as standard (rare) so I don't think it is a 'weakness' in the engine. However, there is a big difference between an engine being used for standard road use and use in competition. Crankshaft regrinds used to be quite common here in the UK but now few people do this as mostly a replacement engine is fitted instead as it is cheaper as labour charges are so high. If building a competition engine I can understand it is better to start with new parts, that is if you can afford them

[david]

The 2000 cranks are steel but they were also nitrided which is a case hardening process that should be redone if the crank is ever reground and I am sure when I read up on this that there is a significant failure rate on manufacture ie the cranks distorting because of the extreme heat.

[paulcas]

Just received some further info from a previous owner of the 131 ( cheers Duncan  )   

Engine: The brief was to build a fast road-use motor and everything necessary to do that was done. More could have been got out of the unit but at the expense of it being as user-friendly.

Crankshaft: Reason for grinding was because there was some wear. The level of grinding required would not have penetrated the thickness of the case hardening.

Cylinder head: Work carried out by a very experienced mechanic who works on 20+ cylinder heads a week - everything from standard repairs to full race work. The head would have been fully flow tested and the head was set up for fast road use.

 

[miro-1980]

Paulsac !

This is very good news and very reassuring !.

Mirafioriman :

You said " As far as I'm aware the 2 litre twin cam has a steel crank as standard (rare) so I don't think it is a 'weakness' in the engine."

Misunderstanding : it actually is much stronger that used in Lancia Delta Integrale for instance.  Fiat 131 crank is  one of the strongest - of not the strongest !  It is a very strong element of the engine.

Weakness comes from regrinding it.  Do not believe in grinding , polishing - yet . but not grinding.

Please look at this : http://www.guy-croft.com/viewtopic.php?f=3&t=2031

Miro