317 or 706 heads on LQ4
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Joined: Mar 2024
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From: Texas
317 or 706 heads on LQ4 Hello, new to the forum. I have a 2002 silverado 1500 that I just picked up a LQ4 to swap in her. I'm wondering should I go with the 706 heads off of my 5.3l that's been rebuilt or should I use some 317 I have on hand? It will have a BTR Stage 2 cam .50 212/218 Valve lift .553/.553. I have plans to run N/A for a while and then go turbo when I want more HP. Which head you all think I should with? I'm willing to any other stock head if needed
Thanks
Thanks
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BTW, polishing ports is hardly done nowadays.
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If the 706s are useable as-is, just run those. Then when you add the turbo, bolt on the 317s. Also consider the SUM-8728R1 cam 212/218 110+3 .600/.585. Similar specs to the BTR Truck Stage 2, but the additional valve lift will complement boost.
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From: Texas
Here is my fully rebuild 6.0L. I have to remove the pistons to regap the rings for turbo. This rebuild its great work! Cant wait to get it in and running!
Hopefully this isn't the long crank that causes issues.
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Depends on the fuel you plan on running. You are limiting boost the more you raise the comp if you are stuck with pump gas. If you plan on E85, then I'd 100% go with the small chamber heads. They will make more power NA and give more power per pound with the boost.
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Putting 706 heads on a LQ4 is alot like how people used to put 396 heads on a 70s 454. Didn't flow near as well, but bumped up the compression a full point; and since the lack of flow only matters at high RPMs anyway, net-net it's a gain. With the cam you're using, the motor will never see the kind of RPMs and whatnot to where the better flow of the 317s really matters, so yeah.
Build a motor EITHER for n/a, OR for boost. Can't do both. It will only work well in AT BEST one or the other situation, and more likely, not in either. What you just did to your rings was a MISTAKE for n/a. I'd suggest taking it back apart, putting in new ones and gapping them right for n/a, use 706 heads, and FORGET about "boost" until the day comes that you're ready to do that; and then AND ONLY THEN build a motor FOR BOOST from the ground up.
Build a motor EITHER for n/a, OR for boost. Can't do both. It will only work well in AT BEST one or the other situation, and more likely, not in either. What you just did to your rings was a MISTAKE for n/a. I'd suggest taking it back apart, putting in new ones and gapping them right for n/a, use 706 heads, and FORGET about "boost" until the day comes that you're ready to do that; and then AND ONLY THEN build a motor FOR BOOST from the ground up.
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So i have done this, and unless you are putting it in a lightweight car and running 93 with octane booster all the time you wolnt have a good time. You will most likley be looking at 10.8/1 with the 706s i have a txspeed cam the same 212/218 low lift it has absolutely no valve overlap so your dynamic compression wolnt change because of it the ONLY way youll be able to run these heads on a truck with 93 or lower pump gas is putting a cam with a bunchhh of overlap look at either high lift longer duration shorter lsa which will idle less smoothly from what ive figured out you want more than 8 degrees overlap more the better for pump gas with the higher compression but you wolnt be idling comfortably, but the 8 or more degrees will lower the dynamic compression to something more usable for the street. in doing this your gonna loose a lot of low end torque and need something like a 3k torque converter and obv with a lift more than .600 youl want ls6 springs or double beehives. if you ever plan to tow with it your gonna want a lot less compression upper 9s lower 10s because the load on the engine will create excess heat and cause detonation unless your running crazy high octane or pull timing way below 20 degrees and at that timing youll be making no power