aren't those some pretty pricey heads though?

 

Expensive, yes, but considering they start life as new, and are CNC'd (not necessarily the best, but certainly gives you a great start), and contain a valvetrain matched to the head, the price is more than fair.

Any built head, even if you start with good cores, will cost alot of money. Head work worth paying for is expensive, no ifs ands or buts about it

 

To me it wasn't bad since there was no core charge and as Z1 said they come with a valvetrain that can handle 10,500 rpm. There are only a handful of people on here with NA motors that have put down as much or more power as my car so to me it was worth it.

 

What about the Nismo heads I saw?




NISMO Competition heads are offered in 2 configurations for the VQ35 engine, the difference being the inner diameter of the valve seat. The Stage 1 heads use a 31mm valveseat, where the Stage 2 uses a 32mm valve seat.

These heads differ from the factory heads in that they have a ported combustion chamber. The stock VQ35 combustion chamber flows 56cc, and these NISMO versions flow 46cc's. This allows for a rise in compresion from 10.3:1 to 12.0:1 with stock pistons.

NISMO Stage 1 Head Set VQ35 $1899.00
NISMO Stage 2 Head Set VQ35 $2499.00

http://z1auto.com/prodmore.asp?model...ine&prodid=923

 

What's your question?

 

How do they compare to the Cosworth heads? It looks like they are sold bare rather than with springs/retainers and such so the price is obviously not a direct comparison, but as far as flow rates and if they have any advantages or disadvantages over the Cosworth heads.

 

I don't think anyone can answer that