cc data for S4 piston and cylinder heads
08-28-2005, 01:57 PM
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cc data for S4 piston and cylinder heads
Does anybody have cc data for 928S4 piston tops and cylinder heads? I'm considering a set of 951 pistons for the Big Kahuna project, but I'd like to keep CR above 8.5:1 or so. At a minimum these will need a longer rod to make them work properly. I'm told the 951 pistons have a 32 cc dish. Rods will have to be about 5mm longer. I want these to fully come to deck level.
Andy, Tony either of you guys have this information?
Andy, Tony either of you guys have this information?
08-28-2005, 02:34 PM
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Great, thanks. I do remember seeing these now. I just ran the math...assuming the data is correct the 951 piston at full deck should yield 8.56:1 CR. This would be ideal, however I'm not sure the cutout in the 951 extends out wide enough for the 4-valve heads. They could easily be trimmed. I could just machine the stock units...but I don't think the cast material is up to the task at hand. I really think I need a forged unit to fully handle the thermal and pressure loads I'm going to put them under. Ideally I want to keep the Alusil bores on the car to shave some costs and significant time out of this build...also the Mahle units are designed for the Reynolds 390 bore...it is a win win. Such a shame there are no 4.5 liter forged pistons out there from Mahle.
