What pistons should I go with?
02-15-2017, 05:51 PM
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What pistons should I go with? I'm currently building a 5.3l LM7 engine for my 04 Silverado 4x4. I'm installing a 78mm turbo, 224/228 .600"/.600" 114lsa Texas Speed cam, 3200 Circle D stall, #60 injectors, 320LPH fuel pump and a couple more odds and ends.. I don't know anyone awful lot about building a motor and I'm wanting to upgrade to forged pistons to help hold up to the extra, I'm wanting to push around 12psi. Could someone help me figure out what pistons and rings know should buy and would I need to upgrade my crank? I have 706 heads. I'm not sure if that information is important.
THANK YOU.
02-15-2017, 09:24 PM
#2
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At 12 PSI you should be fine with stock pistons and crank, as long as your tune is done right. I'd save your pennies. You will run out of 60# injectors, and a 320LPH pump before you need pistons and crank. Don't get me wrong there is nothing wrong with upgrading your pistons and crank, just there are a lot of people running more boost than that on stock pistons, and crank. It is not recommended, but people have made close to 1000 hp on stock bottom ends. If you have the pistons out of the engine you could file the ring gaps to like 0.026-0.028" but that's all I would do at the power levels your shooting for. The key to having it live is a good tune, nice and rich in boost, and not too much timing. E85 is also a good idea is you can make it work.
02-15-2017, 09:47 PM
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At 12 PSI you should be fine with stock pistons and crank, as long as your tune is done right. I'd save your pennies. You will run out of 60# injectors, and a 320LPH pump before you need pistons and crank. Don't get me wrong there is nothing wrong with upgrading your pistons and crank, just there are a lot of people running more boost than that on stock pistons, and crank. It is not recommended, but people have made close to 1000 hp on stock bottom ends. If you have the pistons out of the engine you could file the ring gaps to like 0.026-0.028" but that's all I would do at the power levels your shooting for. The key to having it live is a good tune, nice and rich in boost, and not too much timing. E85 is also a good idea is you can make it work.
02-15-2017, 10:00 PM
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The ring gap is the top and 2nd ring, the compressions rings. They are gapped when at room temperature, so when the engine is up to operating temperature, and the rings expand they don't touch. If they touch they don't move up and down the bore smoothly, since they will be too big for the bore, and they will crack. From the factory they are gapped about 0.018-0.020". Since a turbo engine will be loaded higher, and running hotter, the pistons will get warmer and make the rings expand more. Gapping them larger makes up for this extra heat. You can probably find a YouTube video on how to gap piston rings. This is not absolutely necessary, but good insurance.
02-15-2017, 10:24 PM
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The ring gap is the top and 2nd ring, the compressions rings. They are gapped when at room temperature, so when the engine is up to operating temperature, and the rings expand they don't touch. If they touch they don't move up and down the bore smoothly, since they will be too big for the bore, and they will crack. From the factory they are gapped about 0.018-0.020". Since a turbo engine will be loaded higher, and running hotter, the pistons will get warmer and make the rings expand more. Gapping them larger makes up for this extra heat. You can probably find a YouTube video on how to gap piston rings. This is not absolutely necessary, but good insurance.