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[quote name='flash' timestamp='1338147342' post='127474']
my concern, as was the one my builder had, was that the sleeves are not really connected to anything. aluminum expands differently than steel, and even more when you remove the interconnecting material. the dissimilar materials meant that there could be gaps forming during heating and cooling periods. proof of that is that the block had to be heated for installation. this was to create the tolerance to install them. what do you think happens when the engine gets hot again? hello. tolerance again.
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That is exactly what I was concerned about. Those were my first thoughts. The thermodynamics, and the differences in alloys expanding, and contracting. I too am eager to see how it turns out, becasue I am still on the fence whether or not to go in this direction. It would mean I could put to use one of my spare blocks, that I wouldnt normally. I have 2 2.5 motors, one of em scored pretty good. Would be nice to sleeve it, to 104mm and use it for something.
86' India red 951 3.0 8v turbo
87' Guards red 951 parts car(scrapped :-( )
93' GP white 968 manual, coupe(restoration/modifications in progress)
"I couldn't find the sports car of my dreams, so I built it myself."Ferdinand Porsche
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[quote name='AJG' timestamp='1342014445' post='129127']
Is this process called electro etching, where the solution is acidic and a current is passed thru it I think. It smooths the surface finish by eroding the peaks as well as increasing the bore size. Installing sleeves by heating the block doesn't sound good, as aluminium softens with heat, therefore if it is fairly low heat then the block won't move far and the interference fit must be minimal. I would far rather freeze the sleeves in liquid oxygen and then quickly assy each sleeve before premature interference(that's a new name for it!) takes place, because that always causes dissapointment. So I'm told.
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If i have it right electro etching was the older method back in the 70's and 80's. As environmental regulations progressed, other processes became more ideal. My guess is it depends on who does it. Im sure some machinists use the older methods.
This is a good read:
http://www.sunnen.co....aspx?NewsID=11 Seems theyve developed more traditional honing techniques that use chemical abrasives, rather than chemical etching, which is a messy process.
Liquid N, or O2 might actually work, but IIRC that stuff isnt cheap, and handling it is a bit of a PITA. All metal alloys soften with heat, its just a matter of how much heat. The Al will expand, and contract around the sleeves upon heating. If done right, I wouldnt imagine it to have much more effect than a heavy heat cycle, depending on the necessary temps.
86' India red 951 3.0 8v turbo
87' Guards red 951 parts car(scrapped :-( )
93' GP white 968 manual, coupe(restoration/modifications in progress)
"I couldn't find the sports car of my dreams, so I built it myself."Ferdinand Porsche
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No O2 in liquid state isnt flammable. Its an oxidizer, an accelerant basically it just feeds combustion. Like N2O in a car nitrous oxide itself isnt flammable but it gives the combustion in your engine more "air" to breathe, making more power. Boost acts the same way essentially, only the reaction changes a bit. Force inducing air into your combustion chamber is an oxidation also. O2 is liquid under pressure, but its not flammable. Fuel, oxygen, and ignition makes a fire, more oxygen, more fuel, and bigger spark...makes an even bigger fire. Seems feasible, but waaay too impractical for a machine shop to do.
86' India red 951 3.0 8v turbo
87' Guards red 951 parts car(scrapped :-( )
93' GP white 968 manual, coupe(restoration/modifications in progress)
"I couldn't find the sports car of my dreams, so I built it myself."Ferdinand Porsche
