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Hello, what could cause this piston (attached) to melt like this?
16psi boost stock 5.3, 16 degrees of timing. Pump gas premium. 11.5 afr Sometimes shoting 75hp n2o wet with a lot of torco on its fuel, going to 10.5 afrs.
Ring gap to 0.030 on first and second. Stock 5.3 rotating assembly from a gen IV but in a gen III block. Siemens deka 80lb
Any thoughts? Need more octane? Weak piston bad luck? Injector failed? Need more ring gap? Other thoughts?
Looks like lean meltdown to me . If the combo has been together for a while on that tune without issue then it's quite likely an injector went bad . Only that hole ? Others are good? No W/M ? Which cyl was it ? 16lbs/16° on pump gas with no W/M and nitrous could be over the edge too
Wowza. Those kind of #'s you posted I'd be running ethanol or a blend of pump/leaded VP fuel, whether it is their 104 or may need to be better like 110. Also adding a 75 shot even with all Torco is just adding more cylinder heat. Stock rotating assembly so then what cylinder heads? What CR?
Last edited by ALL ULL C; Jun 21, 2022 at 03:15 PM.
If it's a wet plate kit on a stock manifold. The turbo boost pushed all the nitrous enrichment fuel to the rear two cylinders so the other cylinders ran lean and you where on the ragged edge to begin with. Melty melty.
I run a 5.3 with untouched factory rings at 16psi 14-15* on cheapest 93 pump I can find. I spray 750ml $1.99 wiper fluid with a AEM progressive controller with a FMIC and do it back to back on the street all day. Motor hasn’t been apart in 5 years and never touched the short block minus the usual cam, timing set and oil pump. That’s got to be team and tune related
if your not intercooled a decent water meth kit on 50/50 will do wonders at a minimum.
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What could cause piston to break like this 
