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L76 from 2008 G8, what is a good head/cam package 450-500Hp

 
Old 06-02-2019, 11:41 AM
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Default L76 from 2008 G8, what is a good head/cam package 450-500Hp

I am wrapping up the build of an LS swapped Miata. The diff is a G80 from a CTS-V, trans is a T6060 with T56 mag tail, and the engine is a 6.0L from a 2008 Pontiac G8. The engine will have a set of long tube headers, the stock intake manifold, and a Corvette Z06 air intake. There is a galaxy of possible head/cam and supporting parts to choose from and with the LS being the most commonly modified engine ever I am sure there are no hassle proven combos. With the absurd power to weight of an LS powered Miata I am not shooting for ultimate power, but I also don't feel great about all the untapped potential. I would like to order up one of the all in one kits and just use a proven formula. They do range widely from the GM performance that claims about 400Hp to the trick flow which claims 550Hp and I would rather have a good reliable combo than a corner cutting kit with big numbers that could be more trouble than it is worth.

What would your go to combo be for this 6.0L?
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Old 06-04-2019, 03:24 PM
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Use the heads that came on the L76. They are LS3 heads with the heavy intake valves. Then do a DOD delete and a stage1 cam of your choosing, I used the Cam Motion Titan 1. With that 6.0 in a Miata you wont hook up anyhow so no need to go radical.
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Old 06-04-2019, 03:26 PM
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Originally Posted by L78steve View Post
Use the heads that came on the L76. They are LS3 heads with the heavy intake valves. Then do a DOD delete and a stage1 cam of your choosing, I used the Cam Motion Titan 1. With that 6.0 in a Miata you wont hook up anyhow so no need to go radical.
^^^^^^This! ^^^^^^^^^
You HAVE good heads, as said above.
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Old 06-04-2019, 03:54 PM
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In that light of a vehicle, the factory VVT cam out of a L92/L9H 2008-2009 Escalade/Hummer would probably be adequate. The VVT could be used as a tunable traction control.

Even the LS2/LS6 cam has enough split for those heads and would be plenty of cam to get a Miata moving.

These factory came may not get you to 450-500hp, but they will allow you to actually drive the car.

Last edited by DavidBoren; 06-04-2019 at 04:11 PM.
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Old 06-04-2019, 04:13 PM
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Just to be clear- The EARLY LS6 and late LS2 cams are the same grind (204/211, .525/.525) while the LATE LS6 cam has far more exhaust duration and lift (211/218, approx. .550/.550)
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Old 06-04-2019, 04:46 PM
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Does the DOD really have much of an impact on performance? I have seen cam kits that do and don't delete it. And these heads should still benefit from a good port job correct? I am not new to engine building but mainly have done Subaru and Ferrari, I have an LSA in my ZL1 but it is bone stock so I haven't done much with LS engines.
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Old 06-04-2019, 04:53 PM
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DOD has very little impact on performance, as it only kills cylinders under light load, BUT it can malfunction and leave you in a tough spot. The DOD lifters (8 of the total) are less than dependable.
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Old 06-04-2019, 05:01 PM
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Active Fuel Management/Displacement On Demand is a system that deactivates half the lifters and effectively turns the engine into a 4cyl for fuel economy. Yes, it very much has an impact on performance, if you are concerned about when you are running on half your cylinders. The system is another thing that can go wrong, and the cams are limited in both duration and lift.

Variable Valve Timing is a completely different system. It is also something that can go wrong, and the cams are still somewhat limited in their duration and lift, but not so much as the AFM/DOD cams. VVT can be used as a great tuning tool to help performance. There are aftermarket VVT cams that go larger by limiting the amount of movement available to the VVT system, whilst still retaining most of its functionality.

You can, and should, get rid of the AFM/DOD system. Getting rid of the VVT is not at all necessary, but it's obviously your choice to make.
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Old 06-04-2019, 07:08 PM
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Maybe I wasn't clear.
NORMALLY, DOD deactivates only 8 out of the 16 lifters and only under very light loads, which does not impact performance at all.
It WILL impact performance a LOT if they fail, and they do on occasion, at the worst of times. Deleting DOD is a good idea.
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Old 06-17-2019, 03:28 PM
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I put an LS376/525 crate motor in my Miata, so I have the factory LS3 heads and the widely despised GMPP ASA camshaft. With long tubes from V8R/Kooks it made 462 rwhp. Tuning that cam was a bit of an adventure, I'm not done yet but it's getting better. You will spend most of your time running around under (sometimes well under) 2000 rpm on just a whiff of throttle. Make sure your cam runs well there, or can at least be tuned to be tolerable. IMHO, factory heads are fine.

Get ready for wheelspin in 3rd gear, even in a straight line. Stay alert. :-)
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Old 06-17-2019, 03:48 PM
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There might be something to be said for a bit bigger heads/cam combo, pushing torque peak to the right, in the quest for more manageable traction....

Recognizing the heads are NOT much of a limitation (at all), I'd still consider a nice CNC port job on them. In that tiny chassis/car, slightly less port velocity isn't gonna hurt a thing!
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