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Some 5.3 ls6 help needed

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Old Jun 30, 2009 | 02:25 AM
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Default Some 5.3 ls6 help needed

Ok guys yall have always helped me when i had a question, So here we go. I have a 5.3out of a 03 gmc truck, well its going in my 2000 tahoe that has a bad 5.3 in it. I have a ls6 cam an ls6heads im not using laying here well im going to put them on the 5.3. Do you guys know what my compression will be on it with the ls6 heads stock will be? Should I mill them any? If so how much and what size pushrods would i need then? What do yall reckon my hp an tq will be with this setup? Thanks guys for the help
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Old Jun 30, 2009 | 03:03 AM
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i would leave the 5.3 heads and cam on it just you will loose some lowend torque going with the ls6 heads and cam the gains from the cam won't be worth it in a heavy suv like that might look into a cam like the speed inc si torque you won't notice much by adding hp to a heavy vechicle but you will notice added torque with this cam you would see around 320hp and 370ish torque at the flywheel
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Old Jun 30, 2009 | 05:39 AM
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See i have it all sitting there so i dont want to buy anything else for it like another cam or anything, i have a tsp231 237 cam sitting around too but the hoe is my wifes daily driver an i just wanted to beef it up a lil so when i drive it i can play with some folks, It stock would hang with ome of the 4.6 gt mustangs around here till about 80mph then they would pull lol. So I wouldnt gain anything by going to the ls6 cam an heads on the 5.3?
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Old Jul 2, 2009 | 03:28 AM
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you would gain maybe 20 hp with the cam swap i have a book that they swapped a ls6 cam into a 5.3 and they had some numbers but you will loose hp by adding the heads i'll look it up and let you know i think with that cam all you will do is move the power range up in the rpm not really any gain for the work
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Old Jul 2, 2009 | 12:42 PM
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will it be 20 rwhp or just 20hp
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Old Jul 2, 2009 | 01:54 PM
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Compression ratio will drop from 9.5:1 to 9.26:1 if you bolt them on as is, but if you mill the heads and run some cometic 0.040 gaskets you'll have 10.2:1. I would not run the LS6 cam in a Tahoe either. If you don't want to buy a cam stick with the stocker.
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Old Jul 3, 2009 | 02:15 AM
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What is the cc on the stock 5.3 head? aswell as the cc on the ls6 head stock? Why would I lose so much power an torque by going to a better head an cam?
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Old Jul 4, 2009 | 09:35 PM
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5.3 head is 61cc and LS6 head is 64cc. The LS6 cam has more duration, but the lobe separation angle is wider than the stock 5.3 cam. This will push the powerband higher in the RPM's and reduce bottom end power. Lowering the compression will only add to the loss of low end. It may make 50 more peak horsepower but the average power and overall acceleration will suffer.

Last edited by 5.3LJimmy; Jul 5, 2009 at 10:51 PM.
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Old Jul 5, 2009 | 03:41 AM
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Ok great thanks for the info, Im going to sell the heads an cam an put the 5.3 to stock. no sense in wasting a good set of heads an cam an not gain enough from it on my wifes daily driver.
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