ARE Heads or new 3-Valve Heads?

[silvertp]

Just a question for some of you folks that gargle race fuel and think in terms of airflow.

Recent news of the ARE heads / availability have my interest perked. Sounds like a "all benefits" (except for cost) mod that will greatly improve my performance. I like that...

However, recent threads indicate a "new" GM 3-valve head that may bolt onto our Z's??? Is this true. If so how are these two different heads likely to compare? In terms of power...horsepower and torque through the power band....and costs???

I realize the truest answers will come after these products are available and tested...but I am curious about what folks think

Does a "heads only" modification make sense?

Thoughts????

[marco383]

I assume that you mean "AFR" rather than "ARE" heads. In any case, there isn't any hard data available for either of these options yet. The 205 cc AFR heads are rumored to (finally) be out in late January, while the 3 valve GM heads are vaporware at this point. We should know a lot more by the Spring, which is when I'll be making a decision whether to upgrade.

[silvertp]

My Bad...AFR it is.

I realize this question is a lot like Radon...pretty hard to grab ahold of ....

I was thinking there may be some theoretical advantage to 3-valve heads that make them inheriently more effective in producing power...such that a 2 valve head would be non-competitive.

[JWz06]

There much more experienced wrench turners here than me, but I would think you would also want to do a cam swap while you're at it. If you are upgrading heads, valves and springs you should spend another $400 on a cam. A cam by itself will probably yield more power gain than a heads only swap.

Good luck.

JWz06.

[z62jag]

Originally posted by silvertp
My Bad...AFR it is.

I realize this question is a lot like Radon...pretty hard to grab ahold of ....

I was thinking there may be some theoretical advantage to 3-valve heads that make them inheriently more effective in producing power...such that a 2 valve head would be non-competitive.

In general, the more air/fuel you can flow the more power you can produce. With a single intake valve there is a size limit over which the valve is actually too big and begins to block the air/fuel flow. Using 2 smaller intake valves allows more air/fuel to flow. My explanation might be less technical that some other's so please feel free to jump in with more/better information.

[AJRZ06]

Another thing to consider is if the exhaust ports on the 3 valve heads are in the same exact position as the 2 valve. If the 3 valve heads are a direct bolt on, hopefully those of us with longtube headers can reutilize them.

[marco383]

As you state, in theory multivalve heads produce more power than plain 'ole two valve designs, but there are a number of variables that will affect the final results. If you study the numbers achieved by the best LS1/LS6 tuners using the currently available heads, they are competitive with some pretty exotic multivalve engines. As one example, the 303 CID Lamborghini Gallardo V10 is rated at 493 flywheel HP. This translates to 1.63 HP/cubic inch. A number of head/cam LS6s have made 470+ RWHP, which converts to 552 flywheel HP, or 1.60 HP/cubic inch.

At least for now, two valves per cylinder and pushrods can still get the job done.

[CJS]

You will be lucky to get the new heads in 18 months, or even 2 years, so you might as well get something now and enjoy it.

[speedpup]

Originally posted by CJS
You will be lucky to get the new heads in 18 months, or even 2 years, so you might as well get something now and enjoy it.

Don't bother waiting life is short. Then when the 3 valves come out you will need to port them too.

[Nabbs]

It is unclear that the LS2 or the LS7 heads will be bolt in. Since the blocks that both use and will use are different from ours, there is a very good chance they will NOT be direct bolt-ins.

There are more true and tested ways to make hp with your LS6 available now.

-N