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Old 12-09-2012, 01:10 PM   #1
Ehrgeiz X
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CNC'd 243 heads gain on LS1?

Before I say anything, I searched and searched, but couldn't find anything solid other than speculation and talks of cam choices. Not what I'm looking for, honestly

So, I'm looking for what gains I'd be getting by dropping some Ai 226cc ported and polished 243 heads on to my LS1. Generally, I see a ~20rwhp gain with non-worked 243 heads for this swap, but what about after the job has been done? Should I expect ~30-40rwhp? Too high? Too low? I just want to know what I should expect after installation. Alternatively, I will also make a thread to show before and after, so hopefully it shows up in the search for anyone who wants to know after me.

Before anyone mentions cams or intake manifolds, I've got that side covered. I'm going to contact Ed Curtis for a custom grind after my car fund (read: wife) allows me to continue my build. Engine mods are as follows: K&N FIPK II (Svede on the way to replace that leaky POS), full exhaust (pacesetters coated LT's, catless mids, Spintech mufflers), elite engineering catch can (best $190 I've spent yet), and a tune from Chuck Anders. Everything else is stock.

Thanks for your time guys
- Doug


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Originally Posted by dizzysn...View Post
But the LS9 doesn't have an intake manifold. It uses a roots style superchar... oh, I see what you did

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Old 12-09-2012, 01:20 PM   #2
svede1212
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Milled too I hope. I have about 61cc combustion chambers (0.025 milled) and a "stage 1-ish" CNC job with larger intake valves. I picked up about 30. You can do better for more money but still a substantial gain right across the board. A FAST 102 with NW 102 TB picked up another ~20.
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Old 12-09-2012, 01:57 PM   #3
Ehrgeiz X
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The heads are currently not milled, and I'm still debating if I want to keep it that way for a possible supercharger in the future, but therein lies the issue. I need to decide on that for sure.

Anyways, the heads already have springs and trunnion upgrade and stuff. Even though they aren't milled, they made good power on my buddies LS2 goat. The TB, intake mani and cam will come later, as stated. My last dyno (with my nasty intake leak), I made 330/343 at 5k RPMs on Chuck's tune, and it was no happy dyno. After these heads, I'd be pretty happy with 350-360rwhp, but we'll see what happens. Thanks for the input Svede!


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Old 12-09-2012, 04:03 PM   #4
Ehrgeiz X
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So, is it safe to say that CNC'd 243/799 heads put on an LS1 generally gains 30-40rwhp?


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Old 12-09-2012, 04:43 PM   #5
batboy
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Probably, but it depends on cam, headers, intake, etc.
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Old 12-09-2012, 08:17 PM   #6
mike27408
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243's are extremely capable of good gains when CNC'd...I still use them right now
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Old 12-09-2012, 10:51 PM   #7
Ehrgeiz X
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Oh, no worries. They're definently going on the car. Just need some time to do it, lol


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Old 12-10-2012, 12:18 AM   #8
sam_gto
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i have ported 243's with the ls6 cam so your power level should be like 10-20 lower than me depending on the rest of your mods.

edit:saw you were getting a cam. you will hit 400 easy
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