LS3 heads versus LS6 heads?

[vannatta20]

I have a 6.0 lq4 engine and came across a set of Ls3 heads with the truck intake for a great price. I also just bought a set of LS6 799 heads for it. I dont know which set to install now.....The ls6 heads are low mileage but the LS3 heads have about 190000 miles on them. I can get a new LS3 intake for 200$ or use the truck intake. Its a daily driver and wanted the LS6 heads for increased compression and torque. The LS3 make a lot more horsepower though...I can sell the LS3 heads easily and buy a nice intake for the LS6 heads to dress up the engine and get a bit more power. What should I do??

[69CST6.0]

Depends on your budget which way you go. The ls3 heads will give you more power but you will need a rectangular port intake and a aftermarket throttle body if going dbc. Also the cam splits are a lot more exhaust biased for the ls3 heads. BTW 799 heads are 5.3l truck heads, They are the same as the 243 ls6 heads minus the sodium filled valves.

[Jon01]

On a stock displacement lq4 I'd just put the cathedral ports on it.

[Blackpony]

The 799 heads have a larger combustion chamber that will keep your cr low. I would do the ls3 if your budget will allow to property set it up.
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[vannatta20]

799 have the smallest chamber out of the 3 pairs of heads I have now. 317s and 823 heads are about the same at 70cc. 799 are 64cc so they will bump up compression

[Blackpony]

Originally Posted by vannatta20

799 have the smallest chamber out of the 3 pairs of heads I have now. 317s and 823 heads are about the same at 70cc. 799 are 64cc so they will bump up compression

My bad you are correct. I was thinking about the 317 truck heads. All these different casting numbers get me confused sometimes.. haha I am use to building sbf's..

[68GMCCustom]

The genIV 6.0L LY6 motors come with L92/LS3 style heads from the factory and make great power with just a cam swap.

[vannatta20]

Well i ended up selling the LS3 heads so ill see how the LS6 heads do with a moderate cam in my 6.0. I have a 6.0 with LS3 heads on my 68 firebird and ill see how this combo compares.

[Super73]

Originally Posted by 69CST6.0

Depends on your budget which way you go. The ls3 heads will give you more power but you will need a rectangular port intake and a aftermarket throttle body if going dbc. Also the cam splits are a lot more exhaust biased for the ls3 heads. BTW 799 heads are 5.3l truck heads, They are the same as the 243 ls6 heads minus the sodium filled valves.

Be careful what you say as "truck heads" can be very confusing. Early 5.3's did not wear either version of the LS6 castings.
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[smoky02]

vannatta I did the LS3 heads and intake on my LQ4 and love it.

[Kainedogg]

I was thinking of doing the LS3 heads my self but for the added cost and the hp increase in the higher rpm range, it just didn't make sense for my truck. If under the other hand if I was building a 408" stroker then the best bang for the buck heads would be the LS3's all day, especially with the valves now unshrouded. On a different note I have driven a buddy's truck with the LY6, cam and tune and it felt as quick, but not staggeringly quicker than a mutual friends older LQ4 with shaved iron heads and very small cam.