Well this was an interesting read, before I got heavily into the G3 engines I helped a friend do a 439 based 5.7 back in 2012 we started with a 04 5.7 block. a set of 4.055 CP pistons with 1.04 pin height and 6.077 length rods(also made by CP Nissan application) . blocked was paralleled decked to 9.25 , running assembly(yes it's different from static assembly) had a deck clearance of .005 ,we hard blocked the lower 2 inches of the water jacket. rod ratio works out to stomp pulling 1.43(SBC 400 is 1.48, plenty of them in the 100k+ mile club), Comp cams 268H 6.1 heads done by RLD , 2.125 intake valve and 1.625 Ex valve stock 6.1 intake ......it was not cheep to build,
it's in a 2007 300 as of this past summer(2019) it has just under 65k miles on the build 80 1/4 passes. runs mid 11s around 116-119 , on 87oct
Since 2016 I've done six 4.25 and two 4.30 stroke 5.7s with bores ranging from stock 3.917 to a 4.08(lots of hard block and we sonic checked 12 different blocks to get the right one but 444 Ci was worth it to him)
I would not boost any build with a 4.25 stroke. the better package is using 4.2 Compstar YY12E48 ,6.10 length rods and 1.04 Pin height Piston, I've done 4 so far this year.
Last week I finished up a 422Ci 5.7 , 4.00X4.20 ICON Ford Piston part # IC613 it's a true flat top ,so valve reliefs need to be machined in to them and they are 1.09 pin height , 6.125 Manley 300M rods ,Compstar 4.20 crank custom Cometec .120 thick head gaskets, Piston to head clearance is .055 dry so running will be around .051/.052 ,just over 12 to 1 compression , it's got Edelbrock heads(67cc) and a New Holly sniper intake. cam is low 600lift and it's just under 750hp NA. at 7100 RPMs.
Don't be afraid to build one...just remember new parts vs new parts it's not cost effective compared to 426Ci 6.1/6.4 build.
10.55 @ 130 , Not bad for NA392 ,4400lbs truck
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