rebore 4.4 v8 block

[POMPIEM5]

Whats the story with the Nikasil block and reboring.
Are the cylinders just coatred or the whole block made of nikasil .
How much can you rebore .
And what are the options if you cant,sleeve or recoat lining of cylinder.
Pls some experience or knowledge about this.

 

[rick540]

Whats the story with the Nikasil block and reboring.
Are the cylinders just coatred or the whole block made of nikasil .
How much can you rebore .
And what are the options if you cant,sleeve or recoat lining of cylinder.
Pls some experience or knowledge about this.

Nikasil (old 4.0 block) is a nickel/silicon carbide coating process.

Alusil (replaced some 4.0 and all 4.4's) is a high silicon "hypereutectic" alloy.

Neither are really typically bored out as they last forever, and it takes some very special equipment however it is possible to fit steel liners, but no gaurantee it will work. Some people clain the block warps after a while and the liners don't hold.

Used engines are by far the cheaper option.

If you want to bore out a 4.4 for greater capacity, rather add a stroker crank as the space between the bores is already narrow.

PM me if you have any specific questions

 

[POMPIEM5]

Thanks Rick. Ok,Alusil.
So the most the time its would just re ringed.Prob just need to be honed .
Cant even go 10 over.Spose they dont even sell over size pistons then.
Interesting,these motors are new to me.

 

[Clownshoe]

I think pre 97 4.4 were nikasil and post 03/97 were alusil.

I have been wondering about nikasil block in SA with our dubious fuel quality... sulfur chowed through the nickle...

 

[P1000]

You cannot re-hone or bore an alusil block without having to re-etch the cylinder walls ($$$$$$). The aluminium is actually etched out of the bores, leaving a very hard silicon crystal structure, porous to oil for the rings to glide on. If the block over heats, you destroy this structure, and you need to treat it again. Nikasil can actually be honed, because it is so hard, you only remove deposits like pieces of old pistons when you hone it. The downside is that sulfur in petrol ate the lining, and left you with soft aluminium.

The rest as rick said.