5.3 build
#2
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I would say no on the 6L heads . The 243's will work but You'll end up with a little lower compression ratio. Are You rebuilding the engine ? I would say use the 5.3L heads as of the heads You've mentioned the 5.3L heads have the smallest combustion chamber and will net You the higher compression ratio .
#3
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317's will give you crazy low compression, too low for most boost combos, and definitely too low for an NA or nitrous build. Some ported 5.3L or Ls6 heads would be a much better choice!
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#4
heads
What do you guys have for a small chamber ported head? This is a aluminum 5.3 with factory coated flat tops going to run a perf cam and open carb intake and carb.
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We have both the ported 5.3L heads and ported LS6 heads that would fit the bill and be relatively easy on the budget!
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Are You sure it's not a 4.8L ? ,,,,,,,,,,,,same bore and all the 4.8L's use flat-tops The only way to tell without vin information and it being aluminum block and all is to measure the stroke .
#13
I'd be willing to bet that you have a L33 with 799 heads. 799 is just a different casting # with the same specs as the 243. Stick with what's on the engine and add a cam to take advantage of the flow numbers. To answer the original question... 317 heads will kill your power for n/a due to the lower compression ratio. If you're going blow, then trade the engine for a LQ4 or something with dished pistons and a lower c/r from the start.
#16
5.3 build
#17
That changes almost everything... for a boat I'd go for torque not HP. The 243 heads will need to be decked ~.030 to retain your c/r, but I think you're going about it wrong. If it were me I'd go with some PRC Stage 2.5 5.3 heads, a .040 head gasket and a cam like a 210/218 high lift with a 113 + 4. That'll give you tons of power for pulling skiers and will do pretty well up high.
#19
#20