question about 5.3l head flow.
03-24-2013, 01:07 PM
#1
question about 5.3l head flow. I got these 5.3L heads for free, they have had some port work done. Im curious if anyone got these heads to flow ~320cfm? the best i have seen is ~300cfm. Just asking if it is possible, has it been done?
If not ill probably just sell them and get PRC stage 3 ls6 heads or 243 heads and have my head guy make them equal to PRC stage 3 ls6 heads.
If not ill probably just sell them and get PRC stage 3 ls6 heads or 243 heads and have my head guy make them equal to PRC stage 3 ls6 heads.
03-24-2013, 01:21 PM
#2
03-24-2013, 01:32 PM
#3
well, i bought the car and it had 440whp. The car has a trashed bottom end so im going to build a forged 408. im shooting for 500whp. Im gonna redo the bottom end, install a different cam. I just dont think the heads will support my goals. but im not an expert so i created this post.
03-24-2013, 06:54 PM
#6
stage 3 heads usually have big valves ment for 4" bores.most stage 1 heads are ported and have stock valves, and make 7 hp less.the tsp 5.3 ported heads are a good deal for the money.
03-24-2013, 07:06 PM
#7
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the 5.3s are nice units cause they have a smaller combustion chamber to increase CR, they can be ported to flow rather well too especially with a good valve job. But 500 rwhp would be much easier with higher flowing heads especially with a 4 inch bore, you would want heads/chambers designed for the bigger bore to give better flame travel
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03-24-2013, 09:20 PM
#9
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They will certainly have great flow numbers, but keep in mind that they have square ports so you will have to replace the intake and get a cam to match the flow numbers with respect to their lift. On a 408 you can go either way with cathedral ports or square. Although the ls3 has higher raw flow numbers, whats more important is air velocity which is what the cathedral ports are great at. There was an article in gm high tech, as long as the cam is matched correctly they performed almost the same. If you plan on going really big in the future the square bore will have more potential. But if you plan on staying under 700 HP then keep to the cathedral because the component cost is usually cheaper.
03-24-2013, 09:35 PM
#10
They will certainly have great flow numbers, but keep in mind that they have square ports so you will have to replace the intake and get a cam to match the flow numbers with respect to their lift. On a 408 you can go either way with cathedral ports or square. Although the ls3 has higher raw flow numbers, whats more important is air velocity which is what the cathedral ports are great at. There was an article in gm high tech, as long as the cam is matched correctly they performed almost the same. If you plan on going really big in the future the square bore will have more potential. But if you plan on staying under 700 HP then keep to the cathedral because the component cost is usually cheaper.
03-24-2013, 09:54 PM
#11
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If you plan on running boost then it would matter even less. But ultimately the higher flow number will have more potential. I would do it once and do it right if that is where you want to end up eventually. Do you plan on replacing the pistons later or are you build a low compression 408 from the get go?
03-24-2013, 10:15 PM
#12
If you plan on running boost then it would matter even less. But ultimately the higher flow number will have more potential. I would do it once and do it right if that is where you want to end up eventually. Do you plan on replacing the pistons later or are you build a low compression 408 from the get go?
