mitsuturbo
Well-known member
Apparently i screwed up and didn't tell the shop what (specifically) to set PTW clearance at, and told them to follow the spec card which shows Mahle Recommendation. Well, the spec card says run them from .0025 - .0030 and add an additional .001-.003 for severe duty "such as forced induction/filled block/nitrous".
The machine shop set it up at .006"
Soooo.. Yep. I'm going to get another block punched out to accomodate these brand new Mahle .040" over pistons. I'm not even going to think about trying to go and run brand new EVERYTHING and have .006" ptw clearance (slop). NO WAY!
I'll use the one block they went too big on in my other gvr4. I figure i can throw some 4g64 (86.5mm) pistons in there after they bore it another .020 (.060" over, total). I suppose it should work out okay as long as i don't go crazy with boost. I dont know what the ring lands look like on a stock 4g64 slug, but i imagine they'll live about as well as non turbo pistons do. I've run the 4g63 9:1 NT's in the past, and they worked fine until i put 20+ psi to them and the ring lands broke. My only concern with this setup would be valve reliefs... I wonder if it's possible to use a 4g64 piston with a 16 valve head.
Time to do some more research. Any input is appreciated.
The machine shop set it up at .006"
Soooo.. Yep. I'm going to get another block punched out to accomodate these brand new Mahle .040" over pistons. I'm not even going to think about trying to go and run brand new EVERYTHING and have .006" ptw clearance (slop). NO WAY!
I'll use the one block they went too big on in my other gvr4. I figure i can throw some 4g64 (86.5mm) pistons in there after they bore it another .020 (.060" over, total). I suppose it should work out okay as long as i don't go crazy with boost. I dont know what the ring lands look like on a stock 4g64 slug, but i imagine they'll live about as well as non turbo pistons do. I've run the 4g63 9:1 NT's in the past, and they worked fine until i put 20+ psi to them and the ring lands broke. My only concern with this setup would be valve reliefs... I wonder if it's possible to use a 4g64 piston with a 16 valve head.
Time to do some more research. Any input is appreciated.
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