Evolution X Stock Pistons
#18
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Learn how to read. I clearly stated that this info IS relevant to what the OP is trying to grasp. You look like you're arguing with yourself here.
Forging and casting are two mutually exclusive processes. Some casting processes approach the strength of forgings, and there are multiple different processes for forging. I've never heard of a forged casting or vice versa.
Michael what are your opinions on the stock piston and rod design? Just looking at the rods, they seem of a slightly more robust design than the Evo 4G63 and 4G64. Can't tell on the pistons, but the top ring lands/crowns seem shorter/thinner than those of a 4G63. I do know the top ring end gap is around 8 thou which is really, really tight. I've built several turbo engines with 22-24 thou up top with similar bores, so 8 thou just seems crazy. But so long as combustion chamber temps are kept in check, that gap will never causes any issues. I suppose the 4B11 runs cooler internally since it's an aluminum block engine...
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http://www.tomeipowered-usa.com/usa/...1_report_e.pdf
But thanks... the photos included there are even more evidence that they're cast.
That grid pattern on the bottom of the piston is a dead giveaway that it's a cast piston. That whole center channel on the underside of the piston would have to be machined on a forged piston, yet the roughness of it implies it is cast. You cannot have fine-grain detail like that forged into a piece. You, however, can have them in a casting. Forged pistons come out as a slug which is roughly the size of the finished piston, and are machined down from there. You can notice the same on forged crankshafts and rods. They're very rounded and almost amorphous compared to cast pieces, and you can always note the large parting line from the forging. Parts of these pistons look that way, but the underside looks like a casting.
I honestly cannot say for certain without holding one in my hand or having some really good photos. Everything I've seen of the stock pistons and that I've read from tuners other than Tomei makes me think they're just a quality casting like every Mitsubishi piston in the past. They almost look identical to the Evo VIII-IX ones except they are full floating and the dimensions differ a bit.
#21
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380-400 is no issue at all. I don't put my car on the dyno, but my Data Log Lab showed around 430 on turbo which was enough to run 11.7 at 3700+lbs. Then I sprayed a 200 shot on top of that (minus 7 degrees of timing of course) and that is what broke them. I don't know what kind of power it was making at that point. It held 100, 125 and one bottle at 150 just fine.
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