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Liners

Not sure what pinned liners are. There was a thread on Rennlist recently where someone had used a steel dowel between the cylinder outer wall and inner block to reinforce the cylinder wall but I think this is not a good solution as it is introducing a point load which will increase stresses in the cylinder wall. Best thing to do is what John Mitchell does and machine away the cylinder altogether and replace with a liner.
 
Is a 44/07 a 2.7 litre? The broken wall is like an advert for a closed deck.
The Bore/Block is machined back Scott, but it looks to me like there are 8 pins to stop the Liner moving and the breakage occurred between two of them. The Pins can be seen equi-spaced around the top of the Cylinder.
I don't like the look of it, - its a 322bhp for 500miles if you're lucky design engine.
I agree, Jon M's engines would be in a different league.

George

944T
964
 
I've never seen pinned liners before [&:] (and wouldn't have spotted them on the pic until George pointed them out)

Hopefully SimonP will see this post and can make a comment (Simon builds the engines for Jon M). That looks a pretty catastrophic failure for only 1bar of boost, though obviously race engines see a much harder life than our road cars do.
 
ORIGINAL: George Elliott

but it looks to me like there are 8 pins to stop the Liner moving and the breakage occurred between two of them.
George

944T
964
Click to expand...

Exactly. That's the problem. With the cylinder walls unsupported the hoop stresses can be equally distributed around the full circumference, but with the dowels you are restricting parts of the cylinder wall and therefore concentrating the stresses at those points. Full decking or liners are the best solution.
 
Heres a photo of a decked block. There is a plate installed that supports the cylinders circumferencially:-




F56A4399C50E47FD88C54E79C5AF4A63.jpg
 
And here's a pinned/dowelled block. The pin supports the cylinder longitudinally but the forces act circumferentially (hoop stresses). Pin causes area of point load as the cylinder wall tries to expand:-




8584577BCB1F43688972FC32A2587572.jpg
 
Scott
Never saw that last attempt before. Mad bit of engineering for sure.
The previous one looks a bit better - but I am still waiting to see a really well sorted 2.5+ litre 951, ideally in hands of some-one who can open up clear tarmac on a competent 996GT3 driver.
George
944t
964
 
the way that ebay engine has received liners looks like and engine designed to fail in exactly the way its ended up failing.

What is curious, is that someone has had some equipment and know how to perform this conversion, but has not had the understanding to know its a bad idea.

Maybe its something that works on cast iron blocks or to repair steel wet liners, but in an aluminium block of the 944 design, its a bad idea. Drilling and pinning it in that way has just manufactured a weakness everywhere that they have a pin. Not only this, the liners are too thick, which will cause big problems by itself.

Removing the bore altogether and using a wet liner of the correct design, or boring it out to take a thin wall dry liner is proven technology that Simon and I have working in several 944 engines.

 
ORIGINAL: sawood12

Heres a photo of a decked block. There is a plate installed that supports the cylinders circumferencially:-




F56A4399C50E47FD88C54E79C5AF4A63.jpg
Click to expand...

That's actually my block Scott. It has the deckplate, thin dry Darton liners, thicker headstuds, dowelled and pegged girdle, and a Cometic head gasket. It's a 2.5L sleeved out to 3L. These modifications should help greatly to reduce any chance of failure. As Jon points out, those sleeves are too thick and the pinning is totally weakening that area. My guess is that it was done by a machine shop that doesn't work on Porsches?
 
Patrick, perhaps they intended to fit jubilee clip's around the top of the bores but forgot? Or maybe Cable ties? [:D][:D][:D]

But seriously, who are Darton, how can they get a thin wall dry liner and presumably increase the bore to get 3 litre capacity, and how are the deck/block/liners connected? Also what material is used for these components? Does it work?

Sorry for all the questions but i am interested.

George

944T
964
 
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