Block material hardness

[QuattroFever]

Long shot but anyone know what grade cast iron the block in an aby is?
trying to work out the hardness.

http://www.atlasfdry.com/grayiron-hardness.htm

[JP]

Tensile strength is around the 30-40k on most VAG applications although there may be some exceptions.

[QuattroFever]

Excellent. That may well be the ticket. You know where that would fit in on this conversion table?

http://www.engineershandbook.com/Tables/hardness.htm

Edit: Gotcha! Psi - metric

Psi / 145.037738007218 my calc won't take full number

30k - 206.84273 N/mm2

40k - 275.79031 N/mm2

[driftin jo]

Excellent. That may well be the ticket. You know where that would fit in on this conversion table?

http://www.engineershandbook.com/Tables/hardness.htm

Tensile strength to hardness conversions are at best a an approximate an can't be used to good effect in a lot of materials, one of which is cast iron !

You will notice in the link you posted above the table says 'Applies for plain carbon and low-alloy steels and cast steel and to a limited extent for high-alloy and/or work hardened steel.'

[Kieron20V]

30-40ksi is around 200-275 N/mm2. Just finished studying this lot. Hope that helps.

[QuattroFever]

Wow too slow

Doesn't need to be exact. As long as it's a good ballpark figure. Looking at coatings and liners etc.

However that conversion does seem way off @ 90hv from what I've been reading. Was expecting around 4-500hv.

[QuattroFever]

http://wzeu.ask.com/r?t=p&d=eu&s=mbluk&c=a&app=mob&l=sem&o=10000997&sv=0a65290e&ip=5284d9e9&id=B954725D8689D7B1E76F927E36C1D155&q=gray+iron+block+hardness&p=1&qs=1&ac=169&g=580f+05Y%mQDhR&cu.wz=0&en=te&io=0&ep=&eo=&b=a003&bc=&br=&tp=d&ec=1&pt=Mechanical%20Properties%20of%20Gray%20Iron&ex=tsrc%3Dtled&url=&u=http://www.mid-atlanticcasting.com/gray-iron-alloys_FEB05.pdf

Link to an interesting pdf on gray iron. Ties in with what JP said perfectly. I think that conversion table is as generic as they come making it pretty much useless.

Where are you repo? A man who knows his austenite from his martensite.

[quattro84]

When did VAG switch to compact graphite iron? The later ACV diesels are CGI right?

[JP]

If fitting liners there is two ways to go. Off the shelf spun steel liners. Or what I've done and the more expensive route custom ductile liners which have a tensile strength of 100-120k depending on manufacturer.

The advantage of going to a ductile liner with a higher tensile strength is it's ability to return to perfect roundness is far greater than the cast grey so on high rpm/boost/load applications you are much less likely to end up with oval bores.

Hth

[caterpillar]

If fitting liners there is two ways to go. Off the shelf spun steel liners. Or what I've done and the more expensive route custom ductile liners which have a tensile strength of 100-120k depending on manufacturer.

The advantage of going to a ductile liner with a higher tensile strength is it's ability to return to perfect roundness is far greater than the cast grey so on high rpm/boost/load applications you are much less likely to end up with oval bores.

Hth

WHY never seen audi engineblocks with so many km on the clock +500000km, they didn't need rebore.. for the race use may be, but for the commen people in the street....
the aluengine, needed liners ...dont know the year of the new alusilblock... may from year 95??

[JP]

I'm using a diesel block and casting material is different from the petrol engine and doesn't like the heat as much so playing safe for longevity. We ran a 2ltr stroker (1.8t) using a diesel block and within 1500miles the bores had ovalled by 0.5thou. 3ltr stroker on a v6 seen bore ovalling within 2000miles with as much as 1thou in the lower part of the bore. But again these are all high boost high rpm engines where the pressures exerted on the bore walls exceed that of the tensile strength of the block.

Take the old Mercedes 500's they run Aluminium bores with nikosil coating and I've seen them completely mint with no wear at 500,000miles. Take the Porsche Cayenne 4.5ltr with the same aluminium bores and coating and they barely last 60,000miles.

In the same token the average I5 engine I pull apart has 1-2thou bore wear when having done over 160,000miles. Worst wear is always on cyl1 and 5. so if someone wishes to keep stock bore size and pistons then liners are an option although no cheaper than a rebore and aftermarket pistons.

[JariP]

How do you know the diesel block casting material is different from petrol engine? Do you know is there any differences in the casting materials of the petrol engine depending when it was made, early vs late models?

How much are the good liners and fitting job done in UK? I tried to get some prices for the liners and fitting here in Finland, but the common answer was something like difficult and expensive...

[JP]

Ductile liners work out around £240 per bore. Spun liners work out at around £160 per bore fitted. All depends on which does it.

I have not tested the block materials but seeing how different engines damage/wear I've come to the conclusion they are different.

[Error404]

what do you class as high boost or load on a 2.5 bottom end JP?

[QuattroFever]

No one want's to touch a cast iron block with nikasil so I've been looking at semi permanent coatings for piston skirts rather than liners now (silly money for liners and coating)

Poetons apticote range, Apticote 450 is the most slippery but 400 more durable. The hard anodize looks good but sounds a bit industrial and might screw with the expansion properties of the piston. Don't want to apply anything so hard that it will wear the bores oval though.