Lq9 head option question

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Nov 28, 2017 | 12:42 PM

Rexv8

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Lq9 head option question

Hey all I have been researching on the LQ9s as I am replacing the LS1 that has knocking in my RX7. I have located an LQ9 from a 04 Escalade and it has about 100K miles on it. I found another one out of a 05 Escalade and that has around 127K miles on it. Should I go with the lower miles (Is there any significant difference between the 04 to 05?).

The pull out will have the 317 heads on it and I was wondering if I should swap it out with 799(243) heads? Or should I just keep the 317 heads and machine it at a shop? If I get the 799 heads I am planning on machining them too. Is there any spec I have to keep in mind when I am having them machined since I want a car that I can daily drive in the streets? I will be swap the cam from my LS1 to the LQ9. Here are the specs for it: 230/234 .600/.602 111 LSA.

I will also swap out the LS6 intake from my LS1 and hope I cross the 400 WHP level current setup makes around 378 HP.

Nov 28, 2017 | 12:46 PM

tech@WS6store

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Use the 243s. dont mill them just have them decked. A good valve job and that's really it.
No difference in 04 and 05 lq9.

Nov 28, 2017 | 12:46 PM

G Atsma

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From: Central Cal.

You realize you are putting a lot more weight on the front of your car going from an aluminum block to an iron one? You WILL notice the difference in handling.

Nov 28, 2017 | 01:33 PM

Rexv8

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Quote:

Originally Posted by tech@WS6store

Use the 243s. dont mill them just have them decked. A good valve job and that's really it.
No difference in 04 and 05 lq9.

Thanks for the info, milling them would increase the compression rate even more than necessary for my application right? What does "decking" do to the heads?

Quote:

Originally Posted by G Atsma

You realize you are putting a lot more weight on the front of your car going from an aluminum block to an iron one? You WILL notice the difference in handling.

Yes I know the LQ9 is considerably heavier about 80 pounds more. But getting a replacement LS1 is expensive. I looked at other forums and people who have switched to LQs said they have not felt a huge amount of difference in the handling.

Nov 28, 2017 | 01:39 PM

tech@WS6store

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Decking just trues up the surface. Milling would take away your ptv clearance on that cam.

Nov 28, 2017 | 02:12 PM

Rexv8

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Quote:

Originally Posted by tech@WS6store

Decking just trues up the surface. Milling would take away your ptv clearance on that cam.

I see, should I port the 243s or will I have issues with PTV clearance with that cam?

Nov 28, 2017 | 02:43 PM

speedtigger

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Quote:

Originally Posted by Rexv8

I see, should I port the 243s or will I have issues with PTV clearance with that cam?

Depending on the intake centerline of that camshaft - you should be able to mill the heads .015"-.020" safely if the cam is on a 109 degree ICL. I would not go more than that.