Hello, I'm looking for some input on which heads to go with. (Quick rundown) Forged 370, F1-R, iron block, C5Z, 6 speed. I'm in the begining stages of the parts collection. My question basically comes down to this, will I see a real performance gain between the 317's or the L-92's. Basically a 9.5:1, spinning 7000RPM @10-14 PSI setup. I own the 317's already so that right there is an advantage. Its going to be a semi-budget build. Not trying to spend every dime, but willing to spend 1,200-2,000 $$.
SO, out of the box comparasion 317's vs L-92's
or lightly ported 317's vs L-92's
Also deck thickness to be factored in. What this really boils down to is catherdral vs square port in a boosted application.
Any serious input is appreciated, Thanks

 

Ok, lets try a new angle. Lets say I will make 750 at the tire with the 317's. How much am I leaving on the table buy not stepping up in the head department ?? Of course boost, CI, RPM, blah.....(you get the picture) being the same. Be it cathedral or rectangle port. I'm trying to put a dollar value on the HP left on the table. Example if I put on the top dollar AFR's and pick up 100 HP at the top of the RPM's, well thats hard to justifiy for $3,000.00 tag. And I think 100 HP is a bit high, but thats why I posted the question. So lets here what you think.
O' yeah, one angle I can think of would be by stepping up to better heads, the deck tends to get better. Which would lend itself to more boost. AKA more HP. As long as detenation is kept cool

 

LOL your still at this Not sure what your asking thought? stock casing you will be changing and fixing the l92 more.

But aftermarket the Catherdral and rectangle port are the same till you get into the the 4k plus ls7 head and cooler **** at the price of 7k.

If anything the catherdral heads will still have more and better intakes out there. but maybe in a year or two the other will catch up

 

I would just go with the 317's.